SOME ASPECTS OF THE ROLE OF WEATHER IN BIRD MIGRATION

DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University

by JEFF SWINE BROAD, B. A., M. A.

****

The Ohio State University 1956

Approved by:

Adviser Department of Zoology and Entomology PREFACE

A research program on the role of weather in bird mi­ gration was established at the Ohio State University in the spring of 1950. This program was initiated by a committee consisting of Dr. A. N. Dingle, Department of Physics; Dr. D. J. Borror, Department of Zoology and Entomology; Dr. L. S. Putnam, Department of Zoology and Entomology, Ohio State University; and Dr. C. A. Darabach, Chief of the Divi­ sion of Wildlife of the Department of Natural Resources. Dr. E. H. Dustman, Leader of the Ohio Cooperative Wildlife Research Unit, joined the committee in 1953. Dr. Putnam became Executive Secretary of the committee and supervised the research program. The grant was made possible by the Research Foundation through the University Committee for the Allocation of Research Grants, and from University funds apportioned by the University Advisory Committee on Research Grants. Through these grants a research fellowship was established, and funds were made available for the purchase of needed equipment, and for technical assistance. For the first two years of the program, Dr. Mildred Miskimen was selected as the Research Fellow, and while on this program completed requirements for the Ph. D.

ii The ultimate objectives of this program are to deter­ mine, to as great an extent as possible, the influence of environmental factors in (1) the initiation of migration, (2) the rate of migration, and (3) the routes followed during migration. ACKNOWLEDGMENTS

A special acknowledgment must go to the faculty committee for this project, and particularly to Dr. L. S. Putnam who supervised the entire program. Dr. E. H. Dustman has critically reviewed papers derived from this research which have been submitted for publication, and he and Dr. D. J. Borror have discussed many aspects of the program with the writer and also have reviewed this disser­ tation. Dr. A. Nelson Dingle has aided with the meteor­ ological aspects of the program. Dr. D. R. Meyer has given valuable advice on aspects of comparative psychology, and he led the attention of the investigator to the possibil­ ities of a gastro-intestinal tract cycle as a part of mi­ gratory physiology. Dr. Mildred Miskimen has aided in the development and expression of many of the concepts. Acknowledgment must be made also to R. W. Winner who loaned some of his 1954 data on black ducks and who has discussed many of the problems of the research with the writer. Acknowledgments are due the following who have contri­ buted to this project: R. D. Alexander, W. L. Franz, C. E. Knoder, R. A. Lewis, C. R. Reese, E. S. Thomas, Alexander Sprunt, Jr., G. J. Zenisek, and the many members of the Wheaton Club, whose field notes were invaluable.

iv V

The Water Engineer's office of the City of Columbus furnished the information regarding water levels, and pro­ vided a large scale map of O'Shaughnessy Reservoir. Re­ cognition is due Jean L. Swinebroad for her help in the field, her critical analysis of this dissertation, and for her patience. TABLB OF CONTENTS

List of Tables------vii List of Figures ------xiv Introduction ------1 Present Status of the Problem ------2 Development of the Research Program ------27 Field Data on the Mallard and Black Duck ------44 Field Data Diving Ducks: Redhead, Ring-necked Duck, and Lesser Scaup Duck ------79 Field Data on Shorebirds ------89 Laboratory Tests ------114 Discussion ------128 Sussaary ------183 Tables ---- ______189 Figures - - - - 281 Appendices 300 0 Literature Cited ------312 s Autobiography ------317

vi LIST CP TABLES

Table 1 Number of Hours Spent in the Field at a

Given Hour- - - - — _ _ _ _ _ -- _ _ _ _ 189

Table 2 Cloud Cover and Wind Velocity Recorded at

0 1Shaughnessy Reservoir Compared with Data

for Columbus, Ohio, Taken from the U. S.

'Heather Bureau Laps, 1953------190

Table 3 Examples of Errors Caused by Lumping Specie 3

Counts------— 191

Table 4 Distribution of Mallards on 0 ’Shaughnessy

Reservoir ------______192

Table 5 Rank of Observation Areas at 0 1Shaughnessy

According to Relative Size, Length of Shore­

line, and Frequency of Observation of

Mallards ------193

Table o Distribution of Black Ducks on 0'Shaughnessy

Reservoir------______194

Table 7 Rank of Observation Areas at 0 ’Shaughnessy

According to Relative Size, Length of Shore­

line, and Frequency of Observation of Black

Ducks------195

Table 8. Decreases in Daily Counts of Black Ducks at

0•Shaughnessy Reservoir and Associated

Weather Data------196

vii viii

Table 9. Increases In Daily Counts o,f Black Ducks

on 0 'Shaughnessy Reservoir and Associated

leather Changes- - - - — - - ______id s

Table 10. Examples of the Location of Black Ducks and

Mallards when in Contiguous Flocks - - - - 201

Table 11. Degree of Cloud Cover in Fall-Winter of

1952 and 1953 Compared to Significant Move­

ment of Mallards and Black Ducks on the

Water- -- _ - ______gQ3

Table 12, Wind Speed and Orientation of Mallards and

Black Ducks Resting on the 'Water ----- 204

Table 13, Wind Velocity and Orientation of Mallards

and Black Ducks Resting on Shore------206

Table 14, Wind Velocity and Orientation of Mallards

and Black Ducks Resting on East Shore at

Zoo Feeding Area------208

Table 15, Freouency of Observation of Black Ducks and

Mallards Resting on Shore In Relation to

Wind Direction------_- -- -- 209

Table 16, Greatest and Most Uniform Flock Densities

Recorded in Observations of 135 Flocks of

Mallards and Black Ducks------210

Table 17, Comparison of size and Density of Flocks of

Blacks and Mallards Resting on the Water- - 211 ix

Table 18. Movements of Mallards Flocks Preceding

Evening Flights in 1954------pig

Table 19. Movements of Black Duck Flocks Preceding

Evening Flights in 1954 ------214

Table 20. Examples of Flock Density Preceding Evening

Flight------215

Table 21. Light Intensity, Temperature, and Time at

Start of Evening Flights of Black Ducks and

Mallards------217

Table 22. Evening Flights - Percent of Total Flight

Taking Off at Various Ranges of Light

Intensity- 218

Table 23. The Relationship of Light Intensity at the

Start of Flight to the Number of Black Ducks

and Mallards in the Area ------221

Table 24. The Relationship of the Total Number of

Black Ducks and Mallards in Total Flight

to the Deration of Take-Off Activity- - - 222

Table 25. The Relationship of the Number of Mallards

and Black Ducks in Evening Flight to the

Percent of the Flight that Occurred Belom

1 0 Foot-candles -- - 223

Table 2 o. The Relationship of the Degree of Cloud

Cover to the Amount of Time the Start of

Evening Flight Deviates from the time of X

Sunset------0 9 4

Table 27. The Helationshio of the Decree of Cloud

Cover to Light Intensity at the Start

of the livening Flight of Mallards and

Black Ducks ------9 0 5

Table 28. The Relationship of the Degree of Cloud

Cover to the Duration of Take-Off Activity

in the Evening Flight of Mallards and Black

Ducks ------226

Table 2S. The Relationship of the Percent of Mallards

and Black Ducks in the Evening Flight that

took Flight at 10 Foot-candles or Below to

the Degree of Cloud Cover ------227

Table 30. Comparison Between the Date and the Per­

cent of the Evening Flight of Mallards and

Black Ducks that Occurred Below 1 0 Foot-

candles------228

Table 31. The Number of Mallards and Black Dxicks in

the Observation Area Compared to the Degree

of Cloud Cover ------— - 229

Table 32. Examples of the Behavior of Mallards and

Black Ducks Flushed Prom the Reservoir- - 230

Table 33. Direction of Evening Flights of Mallards

and Black Ducks------232 xi

T able 5 4 , Comparison of Season and Direction of

Evening Plights of Mallards and Black

Ducks------233

Table 3 3 . Freouency of Observation of Ring-necked

Duck, Lesser Scaup, and Black Duck- - - 234

Table 3 o . Sex Ratio of Lesser Scaup on 0 1 Shaughnessy

Reservoir, Spring 19 53 ------235

Table 3 v . Ring—necked Ducks at Areas b and 7 - - - 23b

Table 3 8 . Orientation of Lesser Scaup with Respect

to V/ind Speed------237

Table S © . Evening Flights of Diving Ducks from Area

8 ------______------. _ 238

Table 4 0 . Frequency of Observation of Shorebirds - 239

Table 4 1 . Total Hours Spent in the Field on Shore-

bird Observations at a Given Hour - - - 241

Table 4 s . Frequency of Observation of Pectoral Sand­

piper at G ’Shaughnessy Reservoir, 1952 and

1953— ------242

Table 4 3 . Frequency of Observation of Least Sandpiper

at 0' Shaughnessy Reservoir - 1952 and 1S53-24P

Table 4 4 . Freouency of Observation of Semipalinated

Sandpiper at 0 1 Shaughnessy Reservoir -

1952 and 1953- 250

Table 4 5 . hater Levels at 0 'Shaughnessy Reservoir- 254 xii

Table 4t>. Pre^uencr of Observation of Shorebirds

Compared to Yater Levels at 0 1 Shaughnes3’'

in the Fall------_ - 0 5 5

Table 47. Freouency of Observation of Killdeer com­

pared to later Levels at 0 1Shaughnessy in

the Fall------25o

Table 48. Frequency of Observation of Dunlin Com­

pared to Water Levels------257

Table 45. Changes in Numbers of Pectoral Sandpiper

at 0 1Shaughnessy------258

Table 50. Increases of Pectoral Sandpiper Counts

Following Passage of Cold Fronts in the

Fall 1952------2el

Table 51. Changes in Numbers of Least Sandpipers at

0 1 Shaughnessy------2t>2

Table 52. Changes in Numbers of Semipalmated Sand­

pipers at 0 ’Shaughnessy------2e>4

Table 53. Changes in Numbers of Dunlins at 0 ’ Shaughnessy-2t>e

Table 54. Number of Birds in Fly-Offs------268

Table 55. Record of Procedure - Test One ----- 271

Table 5b. Record of Procedure - Test Two ----- 273

Table 57. Results of Test One - The Total Number of

Lines Crossed By All Ducks in Each Successive

Five Minute Period------274 xiii

of Lines Crossed by All Ducks in Lack

Successive Three Minute Period------278

Table 59. Temperature and Pood Consumption Compared

with Activity of Five Mallards During the

Test Period ----- ______280 LIST OF FIGURIS

Figure 1. O * Shaughnessy Reservoir------Figure 2. O * Shaughnessy Reservoir. .Vater Area Relation to Water Level------

F igure 3. O ’Shaughnessy Reservoir ’Water Levels - Figure 4. O 'Shaughnessy Reservoir. 'Water Levels and Numbers of Black Ducks - -

F igure 5. Schematic Representation of Aerial V:e. of Flocks of Black Ducks and Mallard;: -

Figure b. Dunlin. Frequency of Observation. O'Shaughnessy Reservoir------

Figure 7. Least Sandpiper and Semipalmated Sand­ piper Summary of Years 1948 to 1954. O *Shaughnessy Reservoir------

Figure 8. Diurnal Activity as Measured by Fly- Off s------

Figure 9. Light Intensity and Fly-Offs- — — — — -

Figure 10. Shorebird Fly-Off Routes. 0 1 Shaughne Reservoir— — -

Figure 11. Light Intesnity Chances In Chamber. Test 1 ...... - — — Figure 12. Light Intensity Changes in Chamber. Test 11 ------

F igu r e 13. Light Intensity Changes "in the Field Sunset on a Cloudless yay ------

x i v LIST CP FIGURES

Figure 1. 0 'Shaughnessy Reservoir------282

Figure 2. 0 'Shaughnessy Reservoir. Water Area in

Relation to Water Level------283

Figure 3. 0 'Shaughnessy Reservoir V/ater Levels - 284

Figure 4. 0'Shaughnessy Reservoir. Water

Levels and Numbers of Black Ducks - - 285

Figure 5. Schematic Representation of Aerial View

of Flocks of Black Ducks and Mallards- 28b

Figure to. Dunlin. Frequenc;/ of Observation.

0 'Shaughnessy Reservoir------287

Figure 7. Least Sandpiper and Semipalmated Sand­

piper Summary of Years 1948 to 1954.

0'Shaughnessy Reservoir------288

Figure 8 . Diurnal Activity as Measured by Fly-

Off s------289

Figure 9. Light Intensity and Fly-Offs------290

Figure 10. Shorebird Fly-Off Routes. 0'Shaughnessy

Reservoir------— -- 292

Figure 11. Light Intesnity Chances in Chamber.

Test 1- — — — — — — — — — — — — — — — — 293

Figure 12. Light Intensity Changes In Chamber•

Test 1 1 ------294

Figure 13. Light Intensity Changes in the Field After

Sunset on a Cloudless aa~ ------0 9 5

xiv XV

PP '‘-T • *g 1 *.*. »' <03 "VI g r O "*"* ^ ^ A“ ^ — ______i~-_ Q ^

F i'otro 15. Summary of Tost 11------297

Figure lo. Doily Totals cf Activity, Test 11- - 298

Figure 17. Cut-away Viev/ cf Test Chamber- - - - 299 INTRODUCTION This study was made to determine what factors were involved in the initiation of migration. A combination of field observations and laboratory tests provided the data for the analysis of factors involved in this study. The field study commenced on August 1, 1952, and ended on February 1, 1955. The vast majority of the field observations were made on ducks and shorebirds. O ’Shaughnessy Reservoir in Delaware County, Ohio, was selected as the main study area due to its proximity to The Ohio State University campus, and also because it was a bird refuge where no hunting was allowed. Some additional observations in Ohio were made at Buckeye Lake in Fairfield County, at Scioto Lakes in Franklin County, and at Magee Marsh in Ottawa County. Four hundred seventy-six hours were devoted to field observations during fall, winter, and spring seasons. This does not include travel time, nor does it include trips when no data were gathered. Table Cl) shows the number of hours of observation in the field at different times of the day. The laboratory studies were conducted at the Orni­ thology Laboratory of the Department of Zoology and Entom­ ology of The Ohio State University.

- 1 - PRESENT STATUS OF THE PROBLEM The majority of the literature on bird migration and weather is based on field observations from which are drawn correlations between observed numbers of birds and weather changes (see appendix for reviews of literature). Very few authors analyze the stimulus-response situa­ tions in any detail, and most of them generalize on data from scattered observations. This method of procedure is due partly to the field work necessary for the study of migration. Inherent in field studies are several errors which, as yet, have not been completely eliminated: 1. Field studies can not definitely estab­ lish cause and effect relationships. 2. The relation between observed numbers of birds and the actual magnitude of migration is not clear. 3. Sufficiently accurate sampling tech­ niques have not been devised which will enable precise measurements of migration. Cause and effect relationships in field studies: Field studies only serve to demonstrate that particu­ lar activities do occur in certain environmental situa­ tions. For example, the correlations between passage of cold f rents and the subsequent appearance of large nu­ mbers of birds indicate that this numerical change can and does occur in association with cold fronts. Field investigations may show a high degree of correlation be- -3-

tween environmental phenomena and an animal's behavior. This most certainly would encourage the belief that a cause and effect relationship has been discovered es­ pecially when such correlations may be predicted with a high degree of accuracy. But no matter how consistent and statistically reliable the correlations, the ultimate investigations must be one in which manipulation of the suspected cause elicits the critical responses. Farner (1950) points out that field studies, however, are of great value in providing clues to the cause and effect relationships that might exist. Relation between observed numbers of birds and actual migration: Little is known of the relation between observed num­ bers and the magnitude of migration. It has been accepted, almost universally, that the number of birds seen is pro­ portional to the magnitude of migration. Moreau (1953) has calculated that 15,000 birds could pass over an observer in the Mediterranean area without there being any concentration of migrants whatever. If this observer savf a concentration of birds from a five-mile wide strip of the country to the north of him, he would see 1400 migrant birds every morning for two months. In view of these figures it is apparent that many migrants -4-

must pass undetected. In many cases the number of birds migrating over a locale is not known; either the move­ ment takes place at night, or the birds are not visible as they fly high overhead. For example, the observed mi­ gration of chaffinches, which apparently occurs at consid­ erable altitudes, may bear little relation to the actual migration (Snow 1953). Generally, one would expect that the more birds seen in an area, the greater the migration, but just what proportion of the flight is represented by grounded birds is unknown. "Moreover, as has become increasingly evident in modern studies of migration when no migrants are seen, it by no means follows that none are passing." (Moreau, 1953; p. 330). The possibility exists that changes in observed numbers of birds do not correlate with the general migration at all but may reflect only a local situation. The Lacks (1953) state that an entirely different impres­ sion of Swallow migration may be had, depending on whether an observer is located in the valleys or the peaks of the Pyrenees. The variation of water levels in lakes and res­ ervoirs is closely correlated with the appearance of mi­ grating snorebirds (see pages 92-94). Unless water re­ -5-

serves are low throughout a large area (state or region wide), only a small part of the total number of migrants would be observed. The number that are seen would depend on the extent of local water level fluctuations. This is, of course, an extremely simple illustration, and few are apt to generalize on shorebird migrations from restricted local data. Yet, local conditions can influence the numbers of birds seen in many ways, Bennett (1952), for example, believes large numbers of migrants in Lincoln park, Chicago, were due largely to wind direction coupled with the barrier effect of Lake Michigan. The length of stopover made by birds would further disguise the relation of observed numbers to actual mi­ gration. Borror (1948) noted that at Columbus, Ohio, banded white-throated sparrows stayed an average of over 8 days in the fall and over 5 days in the spring. The records of naturally marked sandpipers referred to on pages 98-99 indicated that some shorebirds stayed at O 1Shaughnessy for several days. Thus counts of shorebirds or of white- throated sparrows may not have reflected migration so much as the persistence (stopover) of some individual -6-

birds. Perhaps an increase in numbers observed in an area actually is an indication of a cessation of migration. Birds flying over an area may be forced down by certain conditions of the environment, resulting in a temporary end of migration and a subsequent period of stopover. Some examples of cessations of migration are given by Lowery (1945, p. 92) and Williams (1945, p. 108) in which during inclement weather, birds appeared in observations areas. Bagg (1950) terms the situation an "arrested wave." The relation between the scope of migration and those birds forced down would depend, it is true, on the number in migration, but it would also depend on the physiological condition of the individual birds, the extent to which the environmental change is stimulatory, the condition and extent of the habitat of the area un­ der observation, the time and duration of the censuses, and the length of stopover of the individual birds. Problems of sampling bird migration: The number of birds observed is, in effect, a type of sample of the migratory population. If all factors were constant from situation to situation, it would be possible to compare census data and arrive at some meas- -7-

ure of the change in magnitude of migration. If some measure were available of the influence of weather on habitat or migration, it would be possible also to compare counts taken when factors were not constant* At present, the available information is not sufficient to permit this to be done, as may be shown by the following example: In 1953 the greatest numbers of dunlins were observed at 0*Shaughnessy on November 3, after the pas­ sage of a cold front. Does this mean that the peak of dunlin migration was passing through the area at that time, or is the number due to the particular stim­ ulating factors of that cold front as compared to pre­ vious and later fronts? Perhaps the development of the mudflats was at an optimum on that date, or perhaps that census was made at an optimum time so that a greater pro­ portion of migrating birds was observed. How much of the change in numbers from the peak count to those seen a week later was due to a difference in migration, and how much was due to a change in weather or habitat? Perhaps greater numbers passed through later than November 3, but fewer stopped at O ’Shaughnessy because of a change in water level there. Before these problems can be solved, some idea must be gained of the relation between the birds seen in an area and those passing through unnoticed. -8-

This is not a nonsensical approach to the problem, for many more birds pass through an area than are seen. In New York State, for example, inventories have shown not more than 25,000 black ducks in the state at a given time, yet banding and bag data indicate that over a half­ million black ducks pass through the area (Crissey, 19551. The length of stopover range is an additional factor that must be considered. Birds may remain for several days in a rather restricted area. The numbers seen may reflect this restricted stopover range, rather than the

general trend of migration. For example, Borror (1948) found that the stopover range of white-throated sparrows was probably only a few acres, and was larger in fall than in spring. The stopover range of semi-palmated and stilt sandpipers is referred to on page 109. Some of the counts of shorebirds made at O*Shaughnessy may be inaccurate because of the local movement of individual birds from one mudflat to another (see page 107). If this situation occurred often, comparison of daily counts may not indicate changes due to migration, but rather those due to the shifting of individuals from one mud- flat to another during the census period. With respect to passerines, Newman states: -9-

"When we go out on a May morning search for migrant species, we are often unable to distinguish the active process of mi­ gration from the mere results of migration. Five thousand birds interrupting their mi­ gration to flit about for an hour in search of food within a square mile of fields and woodland look to the observer much the same as 5000 individuals moving through the same area and being replaced every ten minutes by another 5000.11 (Newman, 1952; p. 4). When attempts are made to analyze the records of several investigations along a migration route of a given species, the problems of accurately interpreting census results becomes increasingly difficult. The various re­ cords may be indicative only of local weather conditions or habitat. The approximate rate of progress of a spe­ cies along its migration route may be ascertained by analyses of compiled records. The exact rate of movement of the bulk of the population may or may not be detected in this way. First arrival dates are very inaccurate. They are influenced not only by the variables discussed above, but also by the distribution and type of censuses conducted by local birders. If conditions are such that the length of stopover is short, or stopover range is limited, the main part of the migration may be missed. As an example, the data on the observed numbers of dunlins may again be examined. Observations at O ’Shaughnessy only on Sundays in 1952 would have in- - 1 0 -

dicated a peak count on October 19 (actual peak October 21); observations only on Sundays in 1953 would have in­ dicated a peak on November 1 (actual peaks on October 31, and again on November 2). These Sunday counts do not seem to yield data too different from that of the daily counts. If, however, the data on pectoral sandpiper is examined in the same way, a considerable difference may be seen. Observations of that species only on Sundays in 1952 would have indicated a peak count on October 12; the early season peak would have been missed completely. Thus, an inadequate number of censuses not only may miss the exact date of peaks (necessary in studies involving weather data), but also may give a misleading idea of what peaks do occur. Daily censuses are a necessity if accurate information on the progress of a species along its route is to be obtained. In early investigations at Ohio State University, daily counts were made of mi­ gratory species of warblers in a 38-acre woodlot just northwest of the University campus. Two problems be­ came apparent. It was difficult to accurately census the woodlot, and it was difficult to determine the re­ liability of the census. An additional complication en­ countered in Ohio was that woodlots are widespread throughout the state, and patches of woods are often - 1 1 -

within 5 miles of each other. Thus when birds were first seen in an area, it could not be discovered whether this was a local or widespread movement unless comparable samplings of migration were taken throughout the major­ ity of favorable habitat along the migration route. In spring migration, birds may have flown from Kentucky to Hocking County in Ohio, some 100 miles in one flight, and then moved 40 miles the next night and arrived in the Columbus area. Observers in southern Ohio may have missed these birds, yet they would be seen in Hocking County and Columbus. Even in a more restricted region the same problem may arise. Birds may alight just south of Columbus and gradually move into the University woods north of the city. Unless observers were scattered throughout the county at proper times, this movement would not be detected. The resulting increase in birds in the University woodlot would be the same whether the birds had come from Kentucky or from just south of Columbus. If it is not known from where the birds come, it is difficult to analyze the factors responsible for migration. No matter what habitat or what species Is being sampled, the method of censusing is important. Counts taken at random times were not considered desirable, as - 1 2 -

the activity of many species of birds changes during the day, and hence, the conspicuousness of the birds changes. Passerines are easier to locate in the early morning be­ cause they sing or display or forage. Waterfowl are easier to count toward the middle of the day since they rest on the water, or along the banks of streams and ponds. Censuses taken at the same time every day should yield the best results. The time of censusing should be constant with respect to time of sunrise, for light in­ tensity seems to be an important factor regulating the activity of many species. Censuses taken through a season at the same clock time (for example, eastern standard time) may actually sample the population during varying states of the birds’ diurnal activity cycle. Shortly after field observations were started at O’Shaughnessy it was realized that during most of the daylight hours the numbers of shorebirds and ducks on the reservoir did not vary more than 10%. This meant that a census taken anytime between 0900 and 1500 hours could serve as the daily count, and as long as counts were taken between those hours, totals for different days could be compared. This is not a refutation of the necessity of making standardized counts. In this particular situation apparently few ducks or shore- -13-

birds left the area during the day. In other areas, or with other species, until a measure is obtained of the time and magnitude of movements in and out of the ob­ servation area, standardized time of censuses would be necessary to obtain daily counts that could be compared. Even censuses taken at the same time with regard to sunrise may not be strictly comparable, for daily weather changes may influence the activity and, consequently, the conspicuousness of birds. Daily censuses do not take into account seasonal changes in habitat and physiology of the bird, all of which may affect the comparative value of the samples. If one also takes into account the influence of stopover and stopover range on daily counts, the problem of obtaining accurate and comparable censuses becomes even greater. This should not be taken to mean that censuses that have been done and are now in progress are of no value; data gained by field counts will provide clues to further intensive investi­ gations, and certainly some valuable general ideas may be drawn from such data. A particular problem is that of the effects of disturbance on counts. Examination of the counts of sandpipers Csee tables 42, 43, 44) indicate that the -14-

counts were no loiver on Sundays, when fishermen and others invaded the area, than on other days when the birds were relatively undisturbed. No correlation was noted between changes in counts of black ducks and any particular day of the week. At 0*Shaughnessy the shore-

birds were usually in rather inaccessible areas. If flushed during the day they still remained on the res­ ervoir (see page 111). The ducks, if disturbed during the day, usually moved to some other area of the res­ ervoir. There was no way of determing what the counts would have been at C^Shaughnessy had no disturbance oc­ curred. In both sandpipers* and ducks, however, some of the decreases may have been caused by disturbance. Both Develin (1954) and Ball (1952) record instances in which disturbance resulted in changes in the number of birds present in a study area. The number of white-throated sparrows seen on the Ohio State University campus is in­ fluenced by disturbance. During the hourly change of classes, many white throats move to the tree tops, and counting these birds then becomes extremely difficult. What influence repeated disturbance of this sort may have, either on the accuracy of the counts or on the actual progress of migration, is as yet undetermined. -15-

Over a period of years many inaccuracies due to sampling may cancel out, and the numbers observed at various sites along a migration route may reflect the actual migration through the region; but unless more accurate sampling techniques are available, even this remains problematical. The use of repeat banding data as exemplified by Borror (1948) and Blake (1953) provides information on stopover length and stopover range, and gives some measure of the magnitude of mi­ gration. Repeat banding data may therefore indicate the relation between observed and actual migration. There are some drawbacks to using repeat banding tech­ niques which limit their application, as these investi­ gators realize, and reference should be made to their papers for the complete discussion. Among the main problems are (1) the trapping of sufficient numbers of migrants to obtain realiable data, (2) calculation of the extent of trap shyness and trap habit, (3) sufficient coverage of habitat with traps, and (4) the restrictions of this technique to certain species. Color banding of waterfowl has proved useful, and repeated sight records of color banded birds may be treated as repeat band data.

In the absence of banded birds, observers in the field are forced to rely on sight records for data. Much reliable information can be gained by sight records, particularly with respect to the stimulus situations which govern the behavior of that portion of the migra­ tory population that is observed. Correlation of census data with weather phenomena: The prevailing trend in bird migration research in this country has been to compare increases in numbers of birds with weather phenomena. Increases in numbers are correlated with U.S. Weather Bureau Data as described on the daily weather maps. There is a source of error in the use of weather map data. Many weather stations are located in urban settlements or at airfields. Weather conditions recorded at these sites are often quite dif­ ferent than those prevailing in the vicinity of study areas. Some examples of this have been presented in table 2. The weather often changes rapidly, and the data shown on the maps may be quite different from those at the study area when migration was initiated. Fronts are drawn between stations largely on the bases of dif­ ferences in wind velocity, barometric pressure, and tem­ perature. The actual position of the front between the stations may vary considerably from that drawn. The advance of a front is shown on weather maps as a smooth -17-

curve. In the field the advance of a front may be marked by veering and backing winds, changing degrees of overcast, and fluctuations in temperature, rather than by an or­ derly progression of phenomena. This irregularity is due to the irregular progression of the front and is in turn related to the effects of local topography and air tem­ perature on the frontal movement. A general idea of the activity and strength of a front may be obtained, however, by observing the rate of the frontal passage as it moves through the country, and by the changes in barometric pressure which accompany it.

A shift in a storm’s path of only a few miles can make a decided difference in weather at a given spot, and this shift may or may not show up on the weather maps, where 50 miles or more may separate stations rep­ resented. The local situation is even more difficult to deduce from weather maps when occluded or stationary fronts are concerned, for the characteristics of these fronts are less definite than those of simple cold f ronts. Conditions aloft may differ from surface conditions.

If attempts are made to correlate long migrational move­ ments with weather, it may well be factors in the con­ ditions aloft that are important, whereas the weather - 1 8 -

maps most frequently used by ornithologists are surface maps. The beginning of a bird*s migration may be stim­ ulated by factors at the surface, and not those aloft; but once in flight, it may be influenced by the wind, temperature, and so forth, aloft. Preston (1955) has observed birds finding, and using high air currents which were moving in directions contrary to that of surface winds. Wolfe sums up the situation regarding the use of weather bureau data when he states: "The climatological and ecological lit­ erature, however, is not without reports showing that conditions as measured by Weather Bureau standards are sometimes astonishingly dissimilar from nearby, or even adjacent, plant and animal habi­ tats” (Wolfe, 1945; p. 3)* From the preceding it can be seen that it is difficult to determine by looking at weather maps Just what the stimulus situation was in a given area at a given time. Preferably data on environmental variables should be collected on the study area. Moreover, the weather map data may not include those items of relevance to the be­ havior studied, and this is a further reason for col­ lecting weather data locally. If local weather measure­ ments are made, the only necessity of using weather maps would be to detect long time trends of air aasses, rates -19-

of frontal movements, and a general idea of regional weather conditions. This has been done in the present study in the analyses of decreases in numbers of birds. Much of the current literature on migration has dealt not with observed decreases of birds, but rather with increases in transient population, probably partly because of the undeniable fascination of spectacular in­ fluxes of birds. This has led to some difficulty in in­ terpreting the data. With increases it is often neces­ sary to postulate the weather phenomena that started the flight of birds into the study area. When studying departures of birds from a study area, the weather phenomena can be recorded at that area, thus, in this case, a postulation as to the stimulus may be made within rather restricted limits. A few selections from the most current literature on this problem will serve to illustrate the situation. Bagg (1950) theorizes that a particular pattern of high and low pressure areas re­ sulting in an intensified northeastward flow of tropical gulf air stimulates spring migration. The hypothesis, briefly, is that, ”... in the spring pronounced movement will take place into or through a given region during the interval between the passage of — 20 -

a warm front through that region and the subsequent arrival of a cold front" (Bagg, op. cit., p. 18). In an attempt to analyze migration, Bagg is forced to hypothesize the stimulus that sets off migration at a distant point; his description of the stimulus includes air movements over most of the U. S. This could hardly be the stimulus for an individual bird. Perhaps Bagg considers the intensified northeastward flow of tropical air to be the local stimulus. The correlations may exist as Bagg has described them; however this does not reveal what initiated the departure of birds from given areas, as no data were available on from where the birds came. In the article being discussed (Bagg, op. cit.), data are advanced to support the general hypothesis. These data represent the observations of several ob­ servers for April 17 through 22, 1948 (the assumption is left to the reader that adequate sampling was going on in the various areas mentioned). Migrants appeared in numbers on April 19 to the 20, in accordance y^ith the hypothesis. Some were also observed on April 22, which does not fit the hypothesis. Bagg (op. cit.) considers the latter birds as hold overs which concentrated in favored localities on April 22, presumably remaining until the next period favorable for migration. Again - 2 1 -

consideration of the increase in numbers has led to more hypothesizing. Bagg Cop, cit.) lists 5 periods (each of a day or two in length) in the spring of 1947, 4 periods in the spring of 1948, and 2 periods in the spring of 1949, when notable influxes or heavy diurnal migration passed Holyoke, Massachusetts. He states that his faith in his hypothesis is based on the study of the meteorological background for those influxes. Either all birds passed through during those influxes, or birds passed through in such a xray that no notable influx was observed. This does not invalidate the hypothesis advanced by Bagg et. al. Cop, cit.) concerning "pronounced movement" which is related to notable increases in observed numbers of birds* An acceptance of this hypothesis, however, should not lead to the creation of a law that all or even the major portion of the migration takes place under these circum­ stances (Reference should be made here to the comments by Crissey on page 8 and from Moreau on page 3). Attention has already been paid to a study by Bennett (see page 5) in which he noticed that birds moving with northwest winds could accumulate in his observation area because

of the barrier effect of Lake Michigan. Bennett states further: -22-

”With strong N.E. winds in the Lake Michigan region, birds migrating froxa areas N. of Chicago would naturally tend to fly southeast with the wind and pass west of Chicago.” (Bennett, 1952; p. 203-205). Northwest winds at the locale and during the season of Bennett*s study, are usually associated with cold fronts; southeast winds, with a warming trend. Yet despite the sampling bias caused by wind direction Bennett concludes: * ’’Early cold fronts in late August and early September were always followed by important warbler migration waves.” (Bennett, op. cit., P. 219). Again, the increases of birds are the local point of attention, even though those may be the results of a local concentration due to the barrier of Lake Michi­ gan and not a wave of migrants. The use of influxes of birds coupled with inaccurate sampling techniques may give rise to unwarranted or contradictory inferences. A recent paper by McClure (1955) will serve to illustrate this point. McClure reports only the results of censuses of October 6, November 2, and November 9, at Hanna Park, Tokyo, Japan. He correlates an increase noted on the 2nd of November with a cold front occuring October 31- November 1. No census data were reported for the days from October 6 to November 2. McClure mentions the study area was filled with thousands of people during the mild weather of November. In different paragraphs he describes -23- presumably the same group of birds as moving both "before", and "with" the cold front. He reports the front as "push­ ing south", and also as "veering north", and concludes the paper with positive statements about the termination of warbler and flycatcher migration without supporting data. As no censuses are reported for the days preceding the arrival of the front, the "increase" due to the front may not exist. The possible disturbing effect on the birds of the people in the study area was not dis­ cussed. Finally, confusion seems to exist in attempt­ ing to describe cause and effect relationships and to determine the position of the birds with reference to the front. If this were the only paper of like approach in the literature, the above criticisms might seem un­ warranted, but a perusal of the literature will indicate that there are too many similar papers. In general, the observer is concerned with the appearance of birds in his area. An attempt is then made to deduce the distant cause of local increases. Svardson describes this as follows: "A study of the co-variation between daily temperature fluctuations and the number of birds counted at a bird station would be most welcome. But the origin of the birds is never known -24-

except in general terms. Therefore, several meteorological stations must be selected, covering the most prob­ able area of departure. The weather maps, though, will often show a cold front, situated between the selected stations, thus leveling the days aver­ age to a less significant value.1* (Svardson, 1952; p. 192). Not all authors ignore the decreases in numbers of birds in their observation areas. Both Svardson (1953) and Dennis (1954) have recorded data concerning the de­ partures of birds from study areas. S.C. Ball (1952) not only analyzes the weather pre­ vailing when bird numbers decreased in an area, but also delves at length into the immediate stimulus for de­ parture. Actually, almost all the same general criticisms can be made of the study of decreases in numbers of trans­ ients that can be made of the study of increases in numbers of transients. The fact that no data are avail­ able on the distance moved by the birds is a serious problem common to both methods. Observers fortunately situated on an island, or on mainland departure points for birds flying over water, have some idea of the min­ imum flight departing birds must make. Ordinarily, however, the observer has little idea how far birds move -25-

after leaving his study area. The central issue still remains, though, that the observer considering decreases can work with the environnental variables at hand, and need not postulate stimulus situations. Consideration of several species: Another situation that is often encountered is the unjustified practice of treating several species as if they were one. It is this which renders less signifi­ cant the nocturnal observations of birds passing across the disc of the moon as advocated by Lowery (1951). Farner (1952) in reviewing the work by Lowery and asso­ ciates suggests that caution be used in the inter­ pretation of their results, as the data cannot be def­ initely assigned to given species. When the data for several species are combined, the results may be mis­ leading. As an example, table 3 shows totals of daily counts of sandpipers over a short period of time. These data, though dealing with small numbers, illustrate the problem. As shown in table 3, the grand total can be increasing While one of the species is actually decreas­ ing in number, or vice versa. Correlations based on the grand total would not be true for all the species com­ bined in it (an exception is the flyoff data which are -26-

based on a number of shorebird species, but here the data are available for each species and are presented in table 54). From the preceding review it may be seen that: 1. Field observations serve only as demonstrations of

situations that may exist between the animal and its environment. These provide clues to cause and effect relations. 2. Information is needed on the relation of observed numbers to the general migration. 3. Data are needed on the factors influencing length of stopover and stopover range. 4. Consistent sampling techniques must be employed which are compatible with the known influence of local factors on the sample. 5. Restraint and judgement must be used when applying weather bureau data to an ecological situation. 6. Undue attention has been given to the observations of spectacular increases in observed populations; in­ sufficient attention has been given to the accurate analyses made possible when examining the decreases of numbers in a local study area. 7. Each species must receive individual attention. Several species cannot be considered together unless -27- data are available that would support such a technique. DEVELOPMENT OP THE RESEARCH PROGRAM Introduction: In one sense, no one can study bird migration per se, for it is not a unit phenomenon. An analogy could be made between the study of bird migration and the study of breeding in birds. The latter phenomenon dif­ fers from species to species. In a given species, breeding is composed of many activities: territorial de­ fense, nest building, courting, and incubation. Bird migration, too, is a series of activities varying from species to species; this viewpoint has been expressed by other investigators (Lack, 1954; Thompson 1949). Of course, biologists study "bird migration’1 as well as ’’breeding behavior,” with the implication being that the study deals with a particular facet of the problem, or it deals with a certain group of birds. Too often, however, bird migration is considered in terms of one activity or as one attribute common to most birds. In the latter approach, migration is considered to have a common origin and similar development in all birds. The intention here is not to recommend that the elements comprising migration be broken down ad infinitum, but rather, that bird migration be recognized as a fluid -28-

grouping of a series of activities, each brought about by particular stimulus situations. It is possible to describe single processes of migration for the purposes of their analyses, though this description necessarily limits the dynamics of the phenomena. Each activity of migration could be described in terms of its physical and chemical properties, but it is also possible to con­ sider the activity in terms of ivhat the organism is ob­ served to be doing. This level of treatment is subject to the same objections as applied to a general “study of migration,'* but it is an intermediate level that must be considered. One of the first overt activities in actual migra­ tion is the taking of flight, and an understanding of the stimulus situation which brings about flight is essential to an understanding of migratory behavior. Either the stimulus situation is unique for the begin­ ning of a migratory flight as compared to such things as a feeding flight or a flight to a roosting area, or the bird varies in threshold level to flight stimuli. The bird may respond to stimuli leading to feeding flights and the like, but the migratory flight stimuli may be below threshold level. In time the bird may become -29- responsive to migratory flight stimuli. Once the bird is in flight, the stimulus for migratory flight must be persistent if the bird is to make a flight of any dis­ tance. Possibly, flight initiation stimuli are the same for migratory and feeding or roosting flights, and wheth­ er or not a migration flight is made depends on the stimulus situation after the bird is on the wing. If it is stated that birds migrate with cold fronts, the in­ ference is that stimuli which initiate and maintain flight are associated with cold fronts. If, however, migration also occurs at times when no cold fronts are present, the inferences are Cl) that different stimuli can bring about migration, (2) that the stimuli in cold fronts are not unicue to them, or (3) that birds differ in threshold level to stimuli which occur irrespective of fronts. If a varying threshold of the bird is assumed to be part of the explanation, then an attempt should be made to discover the cause of this changing threshold. Much migration research in this country has been concerned with the relation between increased numbers of birds and weather factors. As was mentioned previously, little attention has been given to the specific stimulus- -30- response situations which bring about migration. In this study, therefore, an attempt was made to analyze environmental situations which bring about changes in behavior, particularly those types of behavior which may be associated with migration. Nothing in this paper is meant to imply that environmental factors other than those studied were not involved, nor is the implication intended that one factor was entirely responsible for a given situation. Study methods and areas: 1. General plan The problems of making accurate censuses of woodland habitat and of determining the length of the flight bring­ ing birds into an area discouraged studies of warbler movements. Attention was directed toward birds occupy­ ing habitat more restricted in range, and habitat easier to census. In Central Ohio this prompted a consideration of waterfowl and shorebirds. Water areas and mudflats could be censused more accurately than woodlands; the birds were easier to see, and shorebird and duck habitat was discontinuous com­ pared to woodlot habitat. The exact rate of shorebird or duck population turnover was difficult to measure, -31-

and it was difficult to determine just what factors brought birds into an area or from where they had come. Measurements were made of environmental factors while birds were in the study area, and, accordingly, it was considered more significant to determine under what con­ ditions birds departed. Some idea of the circumstances under which birds departed could be obtained by com­ paring weather conditions, measured at the study area, before and after decreases in counts occurred; in many cases some additional information on movements of air masses were obtained from Weather Bureau Data. Unless the observer was able to observe a given group of birds throughout the day (24 hours), he did not know just when the birds left the area. If some were seen flying out of the area in the evening, and there was a decrease in that species the following morning, it might be inferred that the birds were observed in migration. This remains only an inference, as the,birds may have returned to the reservoir only to leave again during the night. Thus, in this study, for shorebirds and ducks, only a general idea could be obtained of weather conditions prevailing at the time of departure of birds from the reservoir, The distances which birds moved after leaving the re­ -32- servoir were not known. The birds nay have made only a short flight or may have wandered from one adjacent feeding area to another. No data were available on how much of the migration took place in series of short dis­ tance movements. Stanford (1953) believes that this may be important, for he suggests that shorebirds seen in Cycenaica make their way northward by easy stages with long stops in between. Decreases may have occurred and not been detected, as new birds could have entered the area in numbers e- crualing or exceeding those that left. If birds had been marked, the departure, and arrival of birds could have been detected. No valid method was found to recognize individual groups of birds. No behavior patterns were noted that could be used to identify birds. Groups of about the same size found at the same locale from day to day may have been the same flocks. On the other hand, the locale may have attracted successive flocks, and the size of the locale may have restricted all flocks to about the same size. The stopover of one group may have influenced the behavior of new groups moving into the area, which would make the identification of particular groups or flocks extremely difficult. Those decreases that were detected were of value, however, as they den- -33- onstrated to some extent under what conditions birds left the area. In the presentation of the data, there­ fore, considerable attention Is paid to decreases in numbers of birds at the study area. 2. Field methods On arriving in an observation area, a count was made of all ducks and shorebirds seen. At the comple­ tion of this count, observations were maintained at the locale where the largest number of birds was found. The exact time and length of censuses, and the number of days when additional observations were made, depended on the concentrations of birds in the areas. Previous investigations at 0*Shaughnessy by Miski- men (1952) had indicated that factors of light, tempera­ ture, cloudiness, and wind were paramount in eliciting certain significant responses. Accordingly, at the time of observation measurements were made of air temperature, wind speed and direction (both included in the term **wind velocity"), and light intensity. The degree of cloud cover was estimated and the progress of frontal movements was noted. Light intensities greater than 250 foot-candles were measured with a General Electric light meter fitted with incidence light adaptors. Light in­ tensities less than 250 foot-candles were measured with -34-

a Weston Model 603 light meter \vhich could be read to 0.1 foot-candle. Light readings were made with the meter directed toward the zenith. Readings were taken on the mudflats where shorebirds were observed, and out in the open by water areas where ducks were observed, to insure a read­ ing of light comparable to that falling on the birds. Wind readings represent an average reading of a five- minute period made ivith a Taylor anemometer held breast high. Air temperature readings were made with a mercury themometer shaded from the sun and held 3 to 4 feet above the ground. In addition to the weather data, records were kept of the number and species of birds arriving in and depart­ ing from the area under observation, the time and light intensity \*hen this took place, and the activity of the birds while in this area. In this way a sample of the activity of birds in the region was obtained. Except in a few cases mentioned later, it was im­ possible to tell whether or not the same birds were being observed on successive days. Thus the total num­ ber of birds observed over the migratory period undoubt­ edly included some repeats. To avoid the misleading -35- idea that such a sight record of a bird always represents a different individual, the term "Frequency of Observa­ tion" is used to describe total records of a species. For example, an avocet was observed on each of six con­ secutive days at O^haughnessy Reservoir. Since the avocet is an accidental migrant in Ohio (Borror, 1950), it was probably the same bird. The total of the daily observation records for avocets that season would be 6. Rather than indicate that the total number of avocets seen was 6, this species is spoken of as having a fre­ quency of observation of 6. The frequency of observa­ tion therefore involves a consideration of stopover periods as well as the numerical status of the species. Other techniques used for a particular species are described under that species. Most of the observations were made with the aid of either a 10X binocular or a 25X spotting scope. Occas­ ionally 7X and 8X binoculars were used to follow groups of birds in flight.

The calendar divisions of fall, winter and spring did not reflect the actual seasons in the field. In this paper the seasons have been designated as "fall-winter" (August 1 to the freeze-up of the reservoir), ’*winter- -36- spring” (from the break-up of the ice to May 1), and "winter” (the time between these two seasons, usually from about December 20 to March 1). 3. Study areas a. 0 1Shaughnessy Reservoir O ’Shaughnessy Reservoir was constructed as a water storage reservoir for the city of Columbus, Ohio. The O’Shaughnessy Dam is located in Delaware County, 14 miles northwest of Columbus, and is a property of the city, managed by the Water Board of Columbus. The im­ poundment of the Scioto River not only provides a water storage area, but has become an important recreational site for the people of Central Ohio. The Columbus Zoo occupies an area just northeast of the dam. The long narrow reservoir is generally less than one-fourth mile wide, except just north of the zoo (see figure 1). The reservoir proper consists of the water area extending north from the dam to the bridge of highway 42 which crosses the Scioto River. Measured along mid channel the reservoir is 6.5 miles long. At the usual winter pool level of 848 feet above sea-level, the water area of the reservoir comprises 940 acres. At maximum pool level of £50 feet, the reservoir water area is 1031 -37- acres. In times of drought or heavy withdrawal of water, the water acreage decreases. Figure 2 shows the relation of water area to water level at O’Shaughnessy* During the year the water levels may fluctuate widely at the reservoir, and this was an important factor in deter­ mining water bird populations. Figure 3 indicates the changes in water level that took place in the last 6 months of 1952, 1953, and 1954. A road parallels the east shore of the reservoir, and another provides access to the west shore. The east shoreline is maintained as a city park area, and scat­ tered trees, shrubs, and expanses of grass cover the area from the waterline to the road paralleling the re­ servoir on that side. On the west shore, farm lands and residential areas extend to the water’s edge. Boats are permitted on the reservoir, and the Leatherlips Yacht Club occupies a site on the west side of the reservoir almost opposite the zoo. In good weather, in late spring, during the summer, and in the early fall many fisherman can be found scattered along the east bank. Picnic parties fill the tables provided near the zoo, and many groups use grassy expanses all along the east bank as picnic sites. All boats are removed from the -38-

reservoir in mid-October, and none are permitted on the

reservoir until the following spring. The area attracts many species of migratory water birds. It is a mecca for members of the Columbus Audubon Society, Wheaton Club, and other groups of bird watchers. Since the reservoir is narrow and both shores are easily accessible, 0*Shaughnessy is an ideal spot to observe water birds. With the aid of a spotting scope, most of the area can be covered from the road along the east side. No hunting is permitted on the reservoir or on the city-owned property on the east bank, though sportsmen hunt the fields and woodlots east of the city property. Hunting occurred on the private property of the west bank. The nearest impoundments to 0*Shaughnessy are Del­ aware Reservoir and Griggs Dam. Delaware Reservoir is located on the Olentangy River 10 miles northeast of O ’Shaughnessy. Griggs Dam is located 10 miles downstream from O*Shaughnessy on the Scioto River. Griggs attracts some birds, but relatively few compared to 0*Shaughnessy, and more often than not only 5 or 10 individual ducks or shorebirds are seen at Griggs. Delaware Reservoir attracts many ducks and shorebirds, but as hunting is permitted in that area, fall populations are disturbed -39- more than at O fShaughnessy. No definite cases of trading of birds between Delaware and O*Shaughnessy Reservoirs were known, but this does not mean that it did not occur; observations in the area were largely limited to the daylight hours, and the terminus of flights of birds from the reservoir was not always ascertained. Several areas on the reservoir were considered main areas of observation. These areas were those locales on the reservoir where the centers of shorebird and duck populations were observed. Arbitrary limits to these areas were set only at the conclusion of this study, and these limits were based on the observed activity of the water birds. The areas of observation on O ’Shaughnessy were as follows: Area 1 includes the region from the dam north to a jutting point of land on the east bank. The cove at the zoo was usually inhabitated by many semi-domesticated ducks and geese. The zoo cove became dry during periods of low water. This area is intensively used by the public both for fishing and boating and for picnicking and fishing along the shore. Near the dam on the west bank is an open field. An extensive pine grove occupies most of the west shore from the open field to the next -40- area. The east bank consists of picnic and park areas and the Columbus Zoo property. Area 1 is the last area to freeze over completely in late winter. The few birds that were observed in area l1 are included in the data of area 2. Area 2 extends from a point of land on the west side to about the place where the reservoir turns northwest (see figure 1), and includes the inlet to the channel leading to area 8. The west bank is occupied by a con­ tinuation of the pine grove of area 1, the property of the Jeffrey Foremen's Club (a park-like area), and, north of the channel mouth, a series of thickets and disturbed woods bordered by grain fields. The east bank is a park­ like area, but no picnic facilities are provided here. This area is utilized mostly by fishermen and bird watchers. As water levels decrease, an extensive mud flat forms. Area 3 is actually a continuation of area 2. The habitat of the east and west banks is like that of area 2. Usually ducks would be massed in the water at area 2; a few stragglers would extend to area 3 and a second massing of ducks would be noted at area 3. A few birds would be found north in area 3* and these were included in the counts of area 3. -41-

Area 4. A bridge marks the southern boundary of Area 4. The northern boundary is marked on the east side by an inlet over which highway 257 passes (see figure 1). The east bank of area 4 is a park area of high relief* The west bank of area 4 has a similar re­ lief, but the south portion is a mixture of thickets and wooded land, while at the north portion a series of miniature cliffs meet the water. Area 5. The west bank of this area is like that in area 2, while the east bank, of low relief to the south, rises in a hill at the juncture of areas 5 and 5* (see figure 1). The north border of area 4 forms the south border of area 5. The northern boundary of area 5 is shown in figure 1 and roughly approximates the beginning of the increase in gradient of the east bank which leads to area 5*. As at areas 2 and 3, two centers of popula­ tions were observed, one at area 4 and one at area 5 with birds scattered in between. Birds observed in area 5f were included in the counts of area 5. Area 6 extends from where the high hill of area 5* drops down almost to water level, to where the river widens south of highway 42. The southern most part of the west bank is a series of small cliffs, while the majority of the rest of the west shore is an open field At its south end, the east shore is a series of low lying points of land which form small grassy marshes during periods of high water. A ridge of higher land extends from the south-east edge of area 7 and at times of high water forms an island in the middle of area 6.

Area 7 comprises the rest of the reservoir from area

6 north to the bridge of Highway 42. Both shores are covered with patches of disturbed swamp forest, except for a stretch along the southern part of the east bank, which retains the park-like character of most of the east bank of the reservoir. At low water stages, the reservoir is reduced to a small stream in area 7, and in the north part of the area 6.

Area 8 is a pond located west of the reservoir proper yet linked with it by a long channel (see figure

1). The south bank of this pond is maintained as a park area, while at the north bank a series of low-lying hills covered with open woods meets the water. When water levels decrease mud flats are rapidly exposed, and an ideal shorebird habitat forms in this area. When water is at its usual level, the area is visited by many fishermen, and then is not usually a good place to observe birds. From the zoo northward, the elevation of the east bank of the reservoir increases. At areas 2 and 3 the -43-

east bank is quite steep, and an observer on the road is

about 20 feet above the reservoir, and about 30 feet

froin the water’s edge. The east bank rises even higher

at area 4. At area 5, 6 and the south portion of area 7,

an observer on the east bank is only two or three feet above the water. This low relief is interrupted by a steep hill forming the east bank of area 5i

b. Other areas of observation:

Observations in the Buckeye Lake area were all made at the Federal Fish Hatchery south of Hebron, Ohio.

Draining of at least one hatchery pond during the fall migration period created a freshly exposed mud flat which attracted migrating shorebirds. The entire mud flat could be kept under observation from one of the en­ closing banks.

Scioto Lakes, located at the south edge of Columbus,

Ohio, consists of four water-filled gravel pits and some smaller ponds near the Columbus Processing Plant.

When water levels fell, a situation similar to that at

O ’Shaughnessy resulted and shorebird activity could be followed quite easily.

In order to check shorebird activity on a con­ tinuous beach area, observations were made at Magee -44-

Marsh in Ottawa County, Ohio. The area visited was a stretch of sand estimated to he 1/2 mile in length bordering Lake Erie. At Magee Marsh it was possible to keep birds in view as they moved along the stretch of sand beach. 4. Laboratory methods Laboratory tests were designed to evaluate the in­ fluence of light intensity on activity of ducks.

Mallards were maintained in an enclosed chamber where they were subjected to controlled variations in light intensity at different times of the day. The relative activity of the birds was determined by observing their movements about the chamber. A detailed description of the techniques is given on page 114. FIELD DATA ON THE MALLARD (Anas platyrhynchos) AND BLACK DUCK (Anas rubripes). Numerical Status of Mallards Resident birds: Mallards were present in varying numbers on 0*Shaughnessy Reservoir throughout 1952, 1953, and 1954. The Columbus Zoo maintained a full-winged flock of mallards, nmscovies, and pekins. Hybridization occurred among these species, and a number of the res­ ident zoo ducks could be identified by their hybrid -45- characteristics. Since these hybrid birds were not known to be migratory, they were not included in the field data. The domesticated ducks and hybrids usually re­ mained near the zoo, but occasionally visited other areas of the reservoir. In the fall-winter period the average number of mal­ lards at the zoo was 200 -/■ 96. In the winter-spring period the average was 64 44. During the fall-winter period the majority of the resident birds remained near the zoo. In the spring these resident birds took up territory and consequently were scattered over the reservoir. Migrant birds occasionally became conditioned to feeding at the zoo, and evidently became temporary mem­ bers of the resident flock, thus increasing the number of mallards observed at the zoo. Birds congregated at the zoo in the morning at feeding time. During the rest of the day most migrants and some of the resident birds moved from the zoo to other areas of the reservoir. Distribution of mallard flocks: The distribution of mallard flocks about the reser­ voir Is presented in table 4. This distribution is based on the frequency of observation of mallards in the various areas of the reservoir. In December the largest groups of mallards were ob­ served at areas 3, 4, and 5, which are the largest areas of the reservoir. Some degree of relation is to be ex­ pected between the size of a water area and the number of birds seen. Obviously the larger the area and the greater the length of shoreline the more space there is available for ducks. Table 5 ranks the observation areas according to the frequency of observation of mallards in the fall-winter period and according to relative size and length of shoreline of the areas. From this table it may be seen that the size of the water area and the length of shoreline are not the only factors influencing the distribution of flocks. The resident flock accounts for the high frequency of ob­ servation of mallards in area 1. A winter kill of giz­ zard shad, providing an abundant and readily available source of food, attracted many ducks to area 8 in the winter-spring period of 1953. Changes in numbers of mallards: Because of the resident mallard population it was not possible to detect the first influx of migrants into the reservoir. Groups of mallards observed in September -47- might have been either zoo residents or migrants. The resident flock had to be taken into consideration in calculations of frequency of observation for mallards. The movements of zoo birds about the reservoir not only obscured decreases and increases in migrant population but made it difficult to detect the degree of change. At times, difference in the behavior of birds at the zoo could be assigned to the presence of migrant ducks. When the ducks were fed at the zoo, a portion of the flock flew to the water at the appearance of the keeper. Other ducks remained on shore vh ile food was being distributed by zoo personnel. On some occasions a flock remained on the water and did not move in to feed until after those on shore had fed. Occasionally some birds flew up when the keeper appeared, but imme­ diately realighted on shore and moved in to feed. Those remaining on shore or returning immediately to shore might have been resident birds. The ducks flying to or remaining on the water might have been migrant birds that were not conditioned to the activity of the keeper. This inference is strengthened by two observations: 1. No black ducks were known to be resident birds. When black ducks were present at the zoo they were among those birds flying to or remaining -48-

on the water. 2. The resident flock did not include more than 215 mallards. When more than that number of mallards were at the feeding area, migrant birds were probably present. On occasions when over 215 mallards were being fed at the zoo, a group of ducks always flew to or re­ mained on the water. Of course, it is possible that some or all the birds flying to the water were those nearest the keeper when he appeared, and thus were stimulated to flight. Other birds, being farther away, were not so stim­ ulated. Because of the resident flock and the difficulty of always being able to separate resident from migrant mal­ lards, no reliable data were obtained concerning the changes in total numbers of mallards present on the res­ ervoir. Therefore, no attempts were made to correlate this particular aspect of the data with problems of mi­ gration. This was done, however, for the black ducks. Numerical Status of Black Ducks Resident birds: No black ducks were known to be permanent residents at O ’Shaughnessy Reservoir. In 1951, black ducks were -49- first noted on the reservoir on October 24 (Miskimen, 1952); on September 10 in 1952; and on October 7 in 1953. In 1954, observations at the reservoir were not started until November, thus no early date for black ducks was obtained that year. Black ducks were present through May of each year when observations terminated.

Pistribut,1.o n o f black duck f locks: Tab,".? 6 shows the distribution of black ducks on O ’Shaughnessy, and a comparison of that distribution with area size and shoreline length is presented in table 7. The largest flocks of black ducks were observed at area 4 which is usually not the largest area of the re­ servoir (except at the 835’ level). Actually the dif­ ference in size of areas 2, 3, and 4 are slight; more­ over the exact size relationship of these areas varies as the v?ater level of the reservoir changes. The size of the area is probably not the only factor affecting flock size. The concentration of boat traffic, pic­ nicking, and fishing in areas 1, 2, 3, and 8 may have forced birds into the relatively undisturbed regions of area 4 and 5. Chances in numbers of black ducks: -50-

The greatest changes in numbers of black ducks are presented in tables 8 and 9. The tables include only data from the fall-winter period of 19 52, 1953, and 1954. Since recounting of groups, when no ducks had left or come in, indicated that an error of up to 10 per cent could occur in counting; only changes in numbers of 15 per cent or over are presented in tables 8 and 9. These tables represent known movements into and out of the area. Table 8 does not reveal any consistent relation be­ tween decreases in numbers of black ducks and frontal movement, temperature change, wind velocity or degree of cloud cover. Table 9 indicates some correlation between cold fronts and the increases in numbers of black ducks. A large number of cold fronts usually moved through the state in the fall-winter period, and some accidental cor­ relation between these fronts and an increase of black ducks might have occurred. There is rather general acceptance of the concept that freezing weather of the north forces ducks to move southward. Freezing weather to the north may have caused the increases in black duck numbers noted each December at G fSh aughnessy Reservoir. -51-

The number of black ducks at O ’Shaughnessy in December seemed to be correlated with water area, which, in turn, is related to water level at the reservoir (see figure 2). More of the ducks moving in from the north might remain on G*Shaughnessy if the water level is high or increasing. The final winter decreases in black ducks on 0*Shaugh­ nessy was correlated each year with freezing of the re­ servoir. By December 17, 1953, and by December 20, 1954, no open water remained on the reservoir, save for a small area near the zoo. As the reservoir progressively froze over from area 7 south, and from the inlets along the shore toward the center, the number of ducks ob­ served at the zoo increased. As long as holes were open in the ice, some birds remained and were found resting on the ice or swimming about on the open water. As the res­ ervoir froze completely, the only black ducks to be seen were mingled with the mallards at the zoo. If the area was completely frozen, at least 50 black ducks remained, and the number again increased as the area began to thaw. In 1953 and 1954 when the reservoir froze over completely, the decrease of black ducks was gradual. -52-

Diurnal Activity of Mallards and Black Dticks milaritv in behavior of mallards and black ducks: Mallards and black ducks responded similarly to many stimuli situations. For this reason, they are included together in the discussion of diurnal activity. During the fall-winter period mallards and black ducks were associated in groups or various sizes (a group of 3 or more birds was designated as a flock). Mallards and black ducks did not always occur inter­ mingled in one flock. Table 10 records a number of ob­ servations when there was a noticeable separation of black ducks from mallards. Unless the groups had been disturbed, or had just moved into an observation area, the mallards were found at or on the west shore; the black ducks found scat­ tered from shore to shore. No records of conflict be­ tween these species were obtained, and the separation of black ducks and mallards was not complete. This does not indicate that interspecific strife is the factor causing separation. It is possible that mallards were more sus- ceptable to disturbance than were black ducks; the con­ tinual human activity on the east shore could have re­ sulted in a westward shift of mallards toward the west shore. Most authors, however, emphasize the wildness of -53-

black ducks. Kortright states: "...the Black Duck is the most sagacious, wary, and wildest of all ducks, and even in capitivity it retains its shyness and distrust of man." (Kortright, 1943; p. 164). The west bank had in places a dense shrub stand, and thicker tree growth occurred on the west bank than on the east bank. This was true at areas 2, 3, 4, 5, and 7, all of which had concentrations of mallard populations. Mallards might have been more attracted to the woody habitat than were the black ducks. This could be the same response which leads mallards to feed in bottom­ land forests. Categories of activity: The observed daily activities of mallards and black ducks may be classified under five categories: (1) resting and sleeping, (2) flying, (3) feeding, (4) pair formation, and (5) moving about on the water. If the birds had their heads tucked under their -wings, they were designated as sleeping. If the birds were sitting on the water and not flying, feeding, or displaying, they were designated as resting. Birds may drift on the water while sleeping, then awake and move back to their former positions and sleep again. For these reasons, resting and sleeping birds were placed -54-

together in one category. The movements considered significant were those in which the entire flock was moving and exhibiting a net directional shift, or those in which the majority of birds in the flock were milling about on the water. If only an occasional bird shifted position, this was not recorded. Mallards and black ducks were observed resting and sleeping at all hours of the day. From 0800 to 1600 hours the majority of the mallards and black ducks in­ termingled periods of sleeping, resting, feeding, and displaying. In the morning before 0700 hours and in the evening after 1500 hours mallards and black ducks flew from the reservoir and fed in cornfields.^- They returned to the reservoir after feeding. Movement on the water Table 11 shows the relation between degree of over­ cast and significant movement on the water between 0800 and 1500 hours. In making table 11, the activities of mallards and black ducks at the time of observation were recorded on a chart for each day. The number of birds or flocks engaged in an activity was not listed.

1. Some birds may have migrated at this time, rather than proceeding to the cornfields. ______-55-

Ilowever, if a particular activity was noted, it was entered in the chart tinder the appropriate day and hour. The percent of days on which movement occurred at the time of observation was calculated on the basis of this list. This calculation did not include movements caused by disturbance. The records used in making table 11 represented observations on 79 percent of the days when mallards were present at the reservoir, and 73 percent of the days when black ducks were present on the reservoir. Thus the sample was thought to be re­ presentative. Table 11 indicates a relation between movement on the water and overcast days. No similar correlation was noted between time of day and movement, excluding move­ ment preceding evening flights* Wind and flock orientation: In any flock resting on the water, the direction in which most birds faced depended on wind velocity (speed and direction) as indicated in table 12. Flocks were observed orienting into winds having speeds as low as 250 feet per minute. The majority of birds, if resting on the water, always faced into winds having speeds in excess of 460 feet per minute. Activity, such as slight movements on the water, stretching or wing flapping, - 56-

might turn birds momentarily away from the wind. With winds in excess of 460 feet per minute, the birds quickly reoriented into the wind. Below wind speeds of 460 feet per minute a return to orientation into the wind did not always follow. The relation between wind speed and orientation of ducks resting on shore was complex. The birds apparently responded both to wind and to the location of the water. As a result they often were found fac­ ing the water while quartering into the wind, and vice versa (See table 13). The topography and vegetative cover of the shoreline was also important in this orientation. Birds resting on the west shore at area 2 were sheltered from northwest, west, or southwest winds, and faced the water regardless of the speed of winds from those directions. A considerable open span of water and rather open shoreline stretched south of area 5, and winds blowing toward area 5 from the south­ west, south or southeast, were relatively unobstructed. Ducks on the west shore at area 5 faced the wind and not the i^ater. A similar situation involving south or southeast winds existed for ducks resting on the east shore just south of area 3. Ducks on the same shore -57- but north of area 3 were sheltered fror. the wind. The resulting orientations are shown in table 13. At the zoo, ducks on shore faced southeast more than any other direction, and as a result they did not face the water and often had their backs to the wind (see table 14). This might be a result of conditioning to the zoo feeding, for in facing southeast, the birds faced the direction from which the keeper appeared. The zoo area is sheltered somewhat from all but west or south­ west winds, and as a consequence winds probably never reached speeds as high in that area as in other areas on the reservoir. A northwest wind was observed to ruffle the back feathers of ducks on shore at the zoo xvithout producing any change in the orientation of the birds. Since the east side of O ’Shaughnessy reservoir is a public park used by fishermen and groups of picnic­ kers, ducks were not found as frequently on that side as on the west side. The frequency of observation of black ducks and mallards resting on either shore during 1952 and 1953 was as follows: Ducks resting on east shore - 2,820 Ducks resting on west shore - 4,302 The disturbances on the east bank might obscure any re- -58- lations between wind velocity and the shore on which ducks rested. Nevertheless black ducks and mallards were sometimes found on the east shore facing the wind. Apparently birds did not rest on a lee shore any more than on a windward shore (see table 15), Flock density and uniformity: ’’Flock density” refers to the distance birds in a flock are from one another. "Flock uniformity” refers to the degree of variation in the distance birds are from one another in a flock. The use of subjective terms to describe flock density and uniformity preclude any com­ parison of these items with regard to different degrees of environmental change. Terms such as "closer", "mod-

* erately compact", "greater", or "less than", are subject to misunderstanding as to the degree of measure they rep­ resent. Personal bias may enter into subjective descrip­ tions of flock density, and the degree of density of a flock may reflect the expectations of an observer. To avoid the above problems, an attempt was made to find a more objective criterion of flock density. The method selected involved measurement of the distance between adjacent ducks in a flock. This distance was expressed in units of length equivalent to the length of one duck. -59- rhis measurement was called LA (body-lengths apart). In practice, the binocular was focused on a group of birds, the body length of one duck was compared to the binocular field diameter at that distance, and from this an estimate of LA of individuals in the group was made. This method, however, did not solve the problem completely. It was subject to certain errors. A per­ sonal bias in estimating LA could still be introduced. The author was not seeking to establish relations be­ tween flock density and any particular environmental variable, and as the comparison between density recorded and these variables was not made until after all data had been assembled, personal bias was not felt to be a factor. Errors could be made in determining LA in large flocks, but this was no more likely to happen on one day than on another. Since the ducks were not all the same distance from the observer, the apparent LA might not be the actual LA. If one duck was behind and off to one side of another, the actual LA might be greater than the LA that was apparent to an observer. Errors might be introduced by estimates of LA on birds not at right angles to the observer. Observation were taken from spots slightly above the water level (see description -60- of observation areas) and the observer was looking down on the flocks, thus errors caused by the position of the ducks with respect to the observer were correspondingly reduced. Errors of this sort did not seem likely to be magnified by any one activity of the ducks as compared to any other, and despite sources of error the LA method was thought to be useful in providing means of comparing flock densities. The LA method was not completely satisfactory as a system of measuring flock densities when birds on the water were courting, or moving about. In these situa­ tions the birds were distributed irregularly on the water, and their position shifted from time to time. The ducks in a flock were not always engaged in the same activity. Ducks in courting parties, for example, were closer to one another than were ducks resting on the water, and courting parties often occurred in the midst of resting birds. When ducks were resting on the water, flocks seemed to consist of irregularly distributed groups; in these groups, ducks were from 1 to 5 LA, and groups were never more than 50 LA. Actually the groups were not completely separated from one another. The groups formed centers of density from which ducks scattered out and mingled with -61-

individuals radiating out froin other density centers. At the fringes of flocks were several individuals, termed stragglers, that were not between groups and were farther from the main part of the flock than any other ducks. Figure 5 shows various flock densities. On occasion, flocks which had been disturbed were observed to have a high density, but it was not known whether this was due to a general tightening up of the flock, or to a movement of those birds nearest the cause of disturbance filling in the spaces between the undis­ turbed birds of the flock. No changes in flock density were observed to accomp­ any changes in wind velocity, temperature, or cloud cover. On one occasion flock density increased with an increase in the intensity of rainfall. When mallards and, or black ducks were resting on shore they remained close together and were within one- half to one LA, with occasional stragglers up to five LA. This flock density was constant for those species when on shore, and flocking was uniform. Whether or not the close flocking on shore was a function of space or of social stimuli was not determined. Space did not seem to be entirely regulatory as 10 ducks would stay one LA in part of a space that could be occupied by 100 ducks, -62-

all one LA. Ducks were observed resting on shore at all

hours of the diurnal period, except during the evening

and morning flight periods; at such times some might have

missed because of the poor visibility at that time of day. Ducks also were observed on shore in winds of from 2,070

feet per minute, and in temperatures of from 1° C to 15° C.

In all of these instances flock density remained one-half to one LA. The most striking changes in flock density occurred just before the evening flights. At that time the lowest and most uniform LA*s for birds on the water were re­ corded. Table 16 indicates the lowest LATs recorded and the activity of the birds when these were noted. In the situations where the LA preceding the evening flights could not be measured, general impressions regarding flock density were noted. These indicate that flock density increased before the majority of the flights took place. A correlation may exist between flock size and flock density (see table 17). When over 400 birds were in a flock, the LA of birds in groups was 1 to 5 or less. This was not consistent, and as table 17 indicates there was considerable variation in the density of flocks of the same size. -63-

The variations in flock density indicate that this aspect of black and mallard behavior is determined by a complex of stimuli. The LA method was not developed to a state where slight changes in flock density could be measured. As no precise measurement of the accuracy of the LA method has yet been devised, no attempt was made to investigate the possible stimuli situations by stat­ istical treatment of the data. Evening flight activity Attention in this study was focused on the types of behavior x^hich might indicate migratory movements, thus, the flight activities of mallards and black ducks were closely observed. The occurrence of evening and morning feeding flights by mallards is widely known and accounts of this activity may be found in many general references. For example (Hochbaum, 1944; Pougfa, 1951). The mallards and black ducks stopping over on O’Shaughnessy Reservoir made feeding flights to grain fields in early morning and late evening. The early morning flights all occurred before there was enough light to make accurate counts of the birds as they left the reservoir, though observers stationed at grain fields visited by the birds could often estimate their numbers as the ducks dropped in to feed. The evening flights -64-

left the reservoir while there was still sufficient light to count the ducks and identify the species in­ volved, At first, observations of the evening flights were made in the hope that the actual start of migration could be observed. Later it was discovered that many birds returned to the reservoir after these evening feeding flights. In the fall, birds leaving the res­ ervoir flying south high in the sky (3, 4, or 5 times tree height), could have been presumed to be migrants, except that on two occasions they were followed to feeding areas just southwest of the reservoir. There­ fore, on the bases of direction of flight or the height of the flight, it was not thought possible to separate migratory movements from feeding flights. Correlations that might have existed between decreases in the numbers of these species and the mode and direction of evening flight preceding the drop in numbers were not considered relevant. The re was no way of knowing whether or not the birds making such flights did not later return to the res­ ervoir and still later at night commence a migratory flight. Some migration might have been started at the time of evening flight and the stimuli for evening flight and for migratory flights may be similar; even if they were not, a delineation of the variables involved in in- -65-

itiation of flight provides a basis for more extended

research.

The evening flight activity is divided into two

parts for convenience in discussion and presentation of

data: (1) preflight activity, and (2) actual initia­

tion of flight. Preflight Activity Unless the birds were disturbed, two general act­ ivities preceded the evening flight from the reservoir; increasing flock density and increasing movement on the ivater. Just when each of these activities commenced, and under what circumstances they began, was not determined. The increase in flock density usually was noted only after the birds were already near 1 LA. The increase in movement on the water started gradually, and was first noted when it had reached a peak. Among mallards flocked near the west shore, groups of four or five began to swim rapidly in one direction or another. Mallards sitting on the shore slipped off into the water and joined them. As the evening progressed the number of birds swimming increased. When the flock density reached 1 LA (see table 20), the majority of the mallards were in motion on the water. This motion and density prevailed until flight took place. -66-

The direction of the swimming seemed to be in­ fluenced by the shoreline. Movement of the mallards was nearly parallel to the shore. Whether all mallards went in one direction, or whether groups went in different directions, seemed to depend on: (1) the relative position of the ducks on the water at the start of the movements, (2) the distance moved before the birds changed direction of movement, (3) the number of birds already moving in one direction or the other. Undotibtedly other factors not noted were also involved. In general, if a large group of birds moved in one direc­ tion others would follow, or if the group became atten­ uated (increasing LA) a reversal of direction of move­ ment could be anticipated. Birds already in separate groups on the water remained separated as often as they merged. The movement on the water did not have any set pattern or predictable sequence (see table 18). Just before the birds took flight they paused in the water and jerked their heads rapidly and repeatedly upward. The head motion preceding flight was the reverse of the head dipping seen in the courting displays. In -67- the preflight head jerk the head was moved rapidly up­ ward and lowered more slowly. Several head jerks occur­ red in rapid succession. Actually the head jerk took place \tfhen the neck was extended, and the action appeared as a nervous movement of the head and neck. Black ducks were usually scattered over the water, and not confined to the west side of the reservoir. Pre­ flight movements on the water of the black ducks did not always parallel the shoreline (see table 19). The black ducks did not become 1 LA until just before take-off, whereas the mallards were closely flocked during much of the movement preceding flight. Previous to flight the black ducks exhibited quick and repeated upward head jerking as did the mallards. The swimming of the mallards did not cease until just before take-off, while the black ducks paused for a longer period of time prior to flight (the exact length of this pause was not ascertained). As in the mallards, the black ducks did not appear to maintain a specific routine or ritual in these preflight movement®. In both species, preflight movement was observed to continue a half hour or more bef ore fl ight occurred. A long period of movement did not always precede flight, especially if the birds were disturbed. On December 6, 1954, at 1630 hours, birds were resting on the water (with black ducks and nallards mixed, indicating previous disturbance). As the observer drove up, the majority moved north. All the birds were 1 LA. At 1651 hours, without any preflight swimming, 175 birds (80 percent of which were mallards) took off. In this instance disturbance might have been a factor. Flock density did not always reach 1 LA before flight occurred (see table 20), as is illustrated by observations of December 14, 1954. Two groups of mal­ lards and black ducks had been moving about on the water. The northernmost group, moving northwest, had split into two smaller groups which then moved toward each other. After joining, they moved northeast, again divided, re­ joined, and then turned and moved southwest. The south­ ernmost group, which had moved northeast, was relatively motionless during the time the north group went through the movements described above. Flock density in the south group was 2 to 3 LA at 1645 hours. The north group was 1 LA at that time. The north group was pre- dominatly mallard, the south group predominatly black ducks. At 1645.5 hours eighty mallards flew up from the north end of the north- group, and the mallards that were -69-

mingled in with the black ducks of the south group also took-off. These were followed by some of the black ducks of the south group. This observation suggested that the density of the flock was not a direct stimulus to flight, and that flight oy others of the same species may serve as a stimulus to take wing. Precise descriptions of the activity preceding flight were not obtained in every case, as attention was focused on the time of take-off and numbers of birds flying in relation to certain weather factors, and, in most instances, this prevented more than a general ob­ servation of preflight activity. Initiation of Flight Although a few birds could be observed flying from the reservoir at almost any hour of the day, the heavi­ est flights occurred before sunrise and just before or after sunset. Most flights during the middle of the day were caused by disturbance of the birds. Those flights observed between 0800 hours and 1500 hours accounted for less than 10 per cent of the birds observed In flights at O ’Shaughnessy. The feasibility of making more accurate observations on the evening flights led to a concentration of attention on them, -70-

rather than on the morning flights.

The per cent of the ducks taking flight at a given light intensity was considered to be of more value in summarizing the situation than the numbers of ducks tak­

ing flight. Use of the latter would place undue emphasis on a large flock whose response may be due to disturbance. The use of percentages, however, gives equal weight to large and small flocks and may thus be in error since it may exclude changes in response due to social interaction. To arrive at a logical method of treatment, percentages were used when the interest was on a species response to stimuli; and numbers were used when the influence of social factors was being examined. As was mentioned, just before taking flight the ducks paused in their movement on the water and repeat­ edly jerked their heads upward. One or more groups of mallards usually left the water before any blacks took flight. In 14 instances the species of ducks that first left the water was recorded; in 13 of these, all of the first group to take wing were mallards. This was felt to be true of 90 per cent of the evenings on which the initiation of flight was noted, even though it was not possible to record the data for every flight. After the first group left the water, others would do so until -71-

a majority of the birds had flown out of the area under observation. Consideration may be given to the environmental changes which might serve as stimuli for flight, partic­ ularly to those factors of the environment changing at the time of evening flight. The most obvious were light intensity and temperature. Wind also varied, and usually decreased in speed toward evening. Table 21 indicates the relation between sunset time (in solar time), tem­ perature, light intensity, number of birds in the ob­ servation area, and time of take-off (corrected to solar time for the longitude of Columbus, Ohio). The time of initiation of evening flight was designated as the time xdien the first birds took off. In all but two cases the first birds off were in groups comprising at least 1% of the total flight for that evening. In the two excep­ tions (December 13, 1954; January 2, 1955) a few birds flew off, individually, long before the first group went up; and these individuals were not considered to 2 mark the start of the evening flight.

2~. Six birds on December 13, 1954 and 5 birds on January 2, 1955.______-72-

The most obvious and rapid enviromlental change was that of light intensity. Table 22 shows the per cent of birds taking off at various light intensities; this table indicates a relation between evening flight and light intensity. Changing light intensity might be an effective va­ riable. The addition of other factors to the stimulus situation would modify the response to light and the flight behavior would not be completely predictable on the basis of light intensity alone. The relative impor­ tance of light intensity as opposed to time of sunset may be compared. An inspection of the relations be­ tween the time of flight initiation and sunset time, and between initiation of flight and light intens­ ity shows that a considerable range exists in both. Plight in the evening was initiated with light intens­ ities ranging from 2 to over 400 foot candles. The morning flights all started at light intensities be­ low 10 foot candles. Evening flight was initiated from 42 minutes before sunset 54 minutes after sunset. Of the thirty-two flights represented in table 21, ten were initiated before sunset. This seemed to invalidate a hypothesis that sunset per se initiates flight. -73-

Air temperature at the initiation of flight ranged from -17° C to 24° C. During some flights no change in temperature was recorded, thus, in those instances changing air temperature could not have initiated flight, unless the birds were responsive to very slight tem- erature changes not recorded. This latter situation seems unlikely. The time of flight initiation dif­ fered on successive evenings having the same temperature which again suggests that temperature changes are not direct stimuli to the initiation of flight. The time of flight initiation was not correlated with changes in wind velocity. There is some danger in using the initiation of flight as a criterion for correlation. If the threshold of response was not the same for all birds in a flock, measurement based on the first bird to respond focuses attention on the extremes rather than the mean. Also, as mallards were usually the first birds off the water, the data on initiation of flight is based largely on mallard behavior. Despite these objections, the time of initiation of flight was considered a better criterion than the mean time of the evening flight. The mean was difficult to determine inasmuch as the birds did not -74- always leave the water in a continual stream, but group after group would take off, with an average of 4.25 / 4.63 minutes between take-offs. The first group off was followed within a few minutes by the second; the average time between the take-off of the first group and the second group was 6.27 / 4.93 minutes. As the interest was centered on the stimuli leading to flight, an analysis of the circumstances under which the first birds took off would prove as valuable in this respect as would an analysis of the average time of flight. It well may be that the take-off of succeeding groups of birds is influenced by their predecessors flight. Should changing light intensity be a factor, then likely circumstances which might result in modifying responses to light are: Cl) The number and kinds of ducks in an area. (2) The degree of cloud cover. (3) Seasonal physiological changes in the ducks. (4) Diurnal physiological changes. (a) Hunger stimuli. (b) Lowered threshold of response due to previous activity. (c) Fatigue of other responses. Ite m (4) can best be tested in a laboratory. Data from -75- the fall-winter period were used for the examination of items Cl), (2), and C3). Not enough information was ob­ tained during February, March, and April to be of value in this analysis, and the presence of numbers of other species might have introduced additional factors modify­ ing the results. Also, in the spring months pairing be­ havior increased and the unity of behavior of large groups of birds was disrupted by sexual display. Accord­ ingly, only fall and winter data dealing with the even­ ing flights were examined and subjected to statistical analysis where correlations were not clear by inspection of the data. The appropriate regression or correlation coefficient was calculated for certain data and the statistical significance of these curves was determined by means of a t table with the 5% level of significance considered critical. The following hypotheses were judged acceptable on this basis: 1. There is a correlation between the number of ducks in an area and the light intensity at which the flight is initiated. As the number of birds increases, flight is generally initiated at a greater light in­ tensity (see table 23). 2. There is no correlation between the number of ducks in an evening flight and the duration of take-off -76-

activity, which is the elapsed time from when the first bird flies up to when the first bird of the last group flies up. (see table 24). 3. There is a correlation between the number of ducks in an evening flight and the per cent of the flight that takes place below 10 foot-candles. U- sually the greater the number of ducks involved in an evening flight, the larger the percentage that take flight at light intensities greater than 10-foot- candles (see table 25). 4. There is a correlation between the time of in­ itiation of flight (with respect to time of sunset), and the degree of overcast. Generally, the more overcast the day the earlier the birds take flight (see table 26). 5. There is no correlation between the light in­ tensity at which flight is initiated and the degree of cloud cover (see table 27). 6. There is a correlation between the duration of takeoff activity and the degree of cloud cover. The more overcast the day, the longer the duration of take-off activity (see table 28). 7. There is a correlation between the per cent of -77- ducks involved in an evening flight that take off below 10 foot-candles and the degree of overcast. The per cent of ducks taking off above 10 foot-candles gener­ ally increases as the degree of overcast increases (see table 29). The influence of seasonal physiological changes on the behavior of evening flight was difficult to detect. A general relation between the date and the seasonal physiological change would be expected, of course; how­ ever, the analyses based on dates are misleading, as the number of ducks increased from October to December and more overcast days were encountered late in the season. Thus a correlation such as the one expressed in table 30 is meaningless, as both degree of overcast and number of ducks can also be correlated with the per cent of the flight taking place below the 10-foot- candles, The latter correlations (degree of overcast or number of ducks as related to per cent of flight be­ low 10 fe.) are meaningful as there liras no acceptable statistical correlation between number of ducks in an area and the degree of overcast, (see table 31) although tvhen overcast days occurred late in the sea­ son, there were usually large numbers of ducks present -78-

(for details see table 60). This makes it difficult to detect the relative degree of influence due to numbers present as compared to the influence exerted by the de­ gree of overcast. Disturbance of the birds resulted in behavior that did not agree with the correlations previously dis­ cussed. The movements of boats about the reservoir, the activities of hunters and their dogs on shore, or dis­ turbances caused by fishermen, bird watchers, and the like, occasionally caused the birds to take flight. The earlier in the afternoon that the birds were flushed, the more of them that would re-settle on the reservoir with­ out making a feeding flight. Conversely, the later they were flushed, i.e., the nearer the time flight would ordinarily have been made, the fewer birds that re­ turned, at least immediately, to the reservoir (see table 32). Data on the direction of flight are presented in table 33, and summarized in table 34. In the fall, a majority of birds went in a southerly direction (like­ wise in the spring, but data for that season were limit­ ed). This should not be interpreted too literally, for the southerly flight direction does not necessarily in­ dicate fall migration. The direction indicated in table 34 is that in which the birds were last seen fly­ ing, and does not account for any turns to feeding areas that the birds might have made after flying from view. Also, duck hunters shot over grain fields in the area, and shifts of direction of flights from evening to even­ ing may have been due to hunting pressure at a given feeding area. Probably the direction of evening flight is related to the direction of the feeding areas. No correlation was noted between light intensity at the initiation of flight and direction of flight. FIELD DATA ON DIVING DUCKS: REDHEAD (Aythya americana). RING-NECKED DUCK (Aythya collaris). AND LESSER SCAUP DUCK (Aythya affinis). Numerical Status Relatively little information was collected on div­ ing ducks, since most of the field work centered on the large flocks of black ducks and mallards. Not all of the species of Aythyinae, Qxyurinae, and Merginae recorded for O'Shaughnessy during the time of this study, were seen in any one fall, and often only one individual of a given species was recorded. In the spring the situation was quite different. All of the species could be seen in any one spring season, with -so- the exception of the scoter and old-squaw. In April it was not uncommon to observe 20 species of waterfowl on the reservoir in one morning. The change in frequency of observation of diving ducks from fall to spring can be illustrated by the data on ring-neclced duck and less­ er scaup for the fall of 1952 and the spring of 1953 (see table 35). Diving ducks may have passed through the area rapidly in the fall, whereas population may have built up gradually in the spring. It is possible that diving ducks migrated over different routes in spring and fall, and the seasonal difference between numbers of scaup observed might have been due to different routes of migration. Possibly a combination of these situa­ tions operated each season and accounted for the dif­ ference in spring and fall observations. The three most numerous species of diving ducks in the area were the lesser scaup, the ring-necked duck, and the redhead. The largest single flock of redheads was observed on March 19, 1953, and was composed of 106 drakes and 76 hens. The largest total number on the reservoir, 245 birds, xvas observed on March 7, 1953. The largest number of ring-necked ducks, 311 birds, was observed on the reservoir on March 21, 1953. -81-

Lesser scaup were the roost numerous of the diving ducks, indicating a greater migration or a longer stop­ over of scaup as compared to the others. The highest number for any one day, 511 birds, was noted on April 2, 1953. The flocks of scaup or redhead were composed largely of drakes. Females predominated in most of the ring-necked duck flocks. The sex ratio in scaup flocks gradually changed as the season progressed (see table 36). If male and female scaup are nearly equal in num­ bers on the breeding grounds then there is probably a differential migration of the sexes through this area. The females might have a different migration route, or may not stop over as long as males, or might migrate later. The data of table 36 could be interpreted either way. Until length of stopover for the sexes is known, these hypotheses cannot be tested. The data may re­ flect an actual inequality of the sex ratio for Hochbaum (1944) notes that males outnumber females in several species of diving ducks, even on the breeding grounds. Diurnal Activity of Daving Ducks Redheads in this area spent most of the daylight hours resting on the waters of the reservoir. Flocks were also observed feeding, preening and courting. Some indication of the rafting behavior of Aythya -82- ducks was shown in the high flock density of resting groups of redheads; the majority of birds in these groups were 1 to 5 LA. The unity of behavior of redheads can be illustrated by observations made on October 30, 1952. On that date at 0910 hours a group of 17 redheads was observed swim­ ming on the reservoir. This group, remaining 1-3LA, passed as a unit through a flock of 250 blacks that were scattered on the water. As the redheads neared the center of the reservoir they stopped swimming; some be­ gan to feed (dive), others preened. A second observation indicating unity of behavior was made on March 7, 1953, at 1125 hours. Sixteen red­ heads appeared in the air over area 3. They flew in from the north and alighted near a flock of 30 Canada geese. A flock of 19 redheads and 10 scaups observed 3 at area 2 had been moving north on the xvater and was noxv opposite area 3. These birds moved toward the geese, where the first group of redheads had just alighted, and passed as a unit through the goose flock thus joining the newcomers. All the redheads and scaup, then in one flock, turned, faced south, and rested on

3Z This flock was observed to be led first by a male scaup, then by a female scaup, and finally by a female redhead. ______the water. Ring-necked ducks could be found resting on the water during any hour of the day. Usually, hotvever, they were found feeding close to shore at scattered spots along the reservoir. During 1951 and 1952 at area 6 and area 7, it seemed that about the same num­ ber of diving ducks was found feeding at certain lo­ calities. It appeared unlikely that a small feeding site at either area would attract only a specific num­ ber of birds. If careful counts revealed the same number of birds on consecutive days at these local­ ities, an assumption that these were the same birds seemed warranted. Observations on the reservoir suggested that ring- necked ducks might be ideal species from which to col­ lect data on this point, as these divers fed in small groups in rather restricted places on the reservoir. Accordingly, ring-necked duck counts at area 6 and 7 in 1953 were conducted as carefully as possible. Con­ siderable effort was made to count every bird in these areas, and it was felt that the counts were accurate within 2 birds. Table 37 shows the results of this count at area 6 and area 7. These areas were considered as one in the table since they were only about 1000 feet -84- apart and birds were observed to move back and forth between them. The data obtained for March 25 through the 27th, and for April 9 through the 15th, and partic­ ularly for April 13 and 14, indicate that possibly a single group of birds was present during each of those periods. Even in this case, however, some variations existed that probably was not due to sampling error. Whether this was the result of movements of a few in­ dividuals of the group, or to a replacement of one group by another was not known. The location and ntm- bers of birds on a reservoir as keys to identification of groups seems worthy of further study, especially if tagged birds have been used to check on the rate of population turnover. Scaup flocks usually were observed resting on the water. They seemed to swim from area to area on the 4 reservoir more than did black or mallard flocks. As in other species of Aythya, resting groups of scaup

~4~l As these comments are based only on the data of the spring of 1953, no tabulation is presented. This is done in full awareness of the danger of advancing even tentative conclusions tirithout presentation of the data on which they are based, but when quantita­ tive data are presented the inclination is strong to analyse them and to draw inferences from them, regardless of the limitations of the sample.______-85- rafted together on the water. The distance between in­ dividuals in these rafts averaged between l/2 and 3LA. Wind and Orientation of Birds on the Water Scaups, redheads, and ring-necked ducks when rest­ ing on the water generally oriented into winds of speeds above 240 feet per minute (see table 38). All the in­ dividuals of a scaup flock seemed to orient into winds above the threshold speed, not just a majority, as with mallards or black ducks. The totality of response may not have been due to wind speed so much as to social factors similar to those responsible for the rafting be­ havior* Evening Flights In the spring of 1953 a kill of gizzard shad in area 8 attracted a large number of ducks to that area. Until March 10, the area seemed to be packed with both diving ducks and surface feeders-*, all feeding on shad. The divers did not spend the night in area 8 but made an evening flight to the reservoir proper, and an early morning flight back to the area. Daving ducks flew into area 8 in the morning before

***After March 10, the surface feeders were practically all gone from area 8 and no more than 10 black ducks or mallards were recorded there. ______-86- there was enough light to give a meter reading (below 0.05 foot-candles), and before they could be seen. As the area was small it was possible to hear the birds as they flew over and alighted in the water. Ducks came into the area at 0545 hours on March 28, and 0547 hours on March 24. On these mornings, the sky was 0.4 and 0.7 degrees overcast respectively. On March 25 the sky was completely overcast and ducks flew in to the area at 0556 hours. The birds flew in compact groups, but after alighting they gradually spread out over the available water area. Birds were at first very active, feeding and chasing one another. Within a half an hour of their landing in the area, some birds stopped feeding and began to sleep on the water. The rest of the day the ducks remained in the area feeding, resting, courting. This activity continued until just before the evening take­ off. At that time groups of two to five birds of one 6 species were observed to swim back and forth over the water in paths which seemed to be less than 10 feet in length. At the conclusion of this movement, the birds stretched their necks up, then flew off the water.

~b~. Species of Aythya -87-

Because of the general activity in the area no data were gathered on the length of the preflight activity of any one species or individual bird. Evening flights fron area 8 were observed on March 9, 10, 12, 13, 14, 24 and April 1, 1953. The ducks were flushed from the water by fishermen on March 12, 13, and 14. On the 12th and 13th some birds returned after be­ ing flushed, and observations were continued. On March 14 the birds were flushed later in the evening and none returned to the area that day. When American mergansers were in the area they were the first ducks to leave and fly out to the reservoir. American golden-eyes took off next, usually shortly fol­ lowed by hooded mergansers. The last groups of birds to leave were the Aythya. though one or two individuals may have taken off earlier. As the light intensity de­ creased, groups of Aythya would take off rapidly one after another until all had left the area (see table 39). The light intensity at the time of take off of the first Aythya was usually below 5 foot-candles. The ducks usually flew from area 8 along the channel to the reservoir, though on April 1, 1953, seventy-five per cent or more of the birds flew north of the channel, -88- over a stand of sugar bush to the reservoir. On that day, also, the birds in the east pond of area 8 swaia dovm the channel to the reservoir. In all of these ob­ servations of evening flights leaving area 8 at least 210 Aythya were present at the time of observation. Observations were made near the place where ducks flying from area 8 we r e apparently spending the night. The observation of March 15 are reproduced below: 1800: At Shorebird Point, 120 ducks (redhead, scaup, ringneck, canvasback, American merganser, mal­ lard) are in the water, resting, and are an average of 3-8 LA. 1808: Light intensity 300 foot-candles. 8 American merganser take off and fly south. 1809: 30 redhead and scaup, and 4 American merganser fly over to area 8. 4 ducks (species?) fly from area 2. 1821: 22 ducks ( species? ) in from the northwest. 1825: Light intensity 48 foot-candles. 24 divers take off and fly to area 8. 5 black ducks fly by headed south. 5 divers take off and fly south. 1836: Light intensity 24 foot-candles. 24 ducks fly by headed south. 14 more ducks fly by headed south. 1844: (from here on numbers refer to groups of diving ducks) 20 into area. 1846: Light intensity 3.2 foot-candles. 21 ducks in, 17 in, 11 in, 5 in, 5 in, 3 ducks in. 1848: Light intensity 2.4 foot-candles. 30 ducks in. 1850: Light intensity 0.8 foot-candles. 55 ducks in. -89-

1852: Light intensity 0.8 foot-candles. 10 ducks in, 10 in, 14 ducks in. 1853 to 1901: (The following numbers refer to the number of birds alighting in the area. Each number refers to a different group of diving ducks) 4, 23, 4, 1, 17, 20, 5, 1, 6, 4, 12, 16, 5, 2, 2, 2, 1. 1906: 9 ducks in. 1908: 7 ducks in. The data of table 39 and the observation of roosting (see above) suggest that light intensity may be a factor in initiating evening flight in these species. With the Aythya, as in black ducks and mallards, other factors may intervene so that the exact effect of light intensity is difficult to determine. FIELD DATA ON SHOREBIRDS Numerical Status The number of shorebirds seen in all areas in Ohio covered in the course of this study is presented in table 40. The number of hours spent observing shorebirds at O ’Shaughnessy Reservoir is dhown in table 41. This does not include the time spent in the field by members of the Weaton Club, whose data for O tShaughnessy were used to supplement counts of shorebirds made by the writer. -90-

At O ’Shaughnessy Reservoir shorebirds were seen in the area over a longer period of time and in greater num­ bers in 1952 than in 1953. In 1954 water levels re­ mained high at O ’Shaughnessy and few shorebirds were re­ ported for the area, which made it impractical to take daily counts. The five species of shorebirds most commonly observed at O*Shaughnessy Reservoir were kill- deer, pectoral sandpiper, least sandpiper, dunlin, and semipalmated sandpiper. The killdeer was a common resident in the area from February to mid-November, and a few individuals could be found the year around. Because of their persistence and abundance, the migration of killdeer was more difficult to detect than that of other shorebirds, therefore, kill­ deer data are not included in this paper. No flock of shorebirds had more than. 100 individuals of any one species, and most flocks were composed of 10 to 30 individuals. The small size of the shorebird flocks was a distinct advantage to the study for the groups were easily followed from one mudflat to another and it was possible to keep track of the activity of in­ dividuals in the small flocks. The biological value of -91-

the data is not lessened because it is derived from small groups, though, numerically, data from larger flocks would be more impressive. The data obtained from small flocks may be used as a basis for further observations on larger ag­ gregations of birds. Increased flock size may be ex­ pected to have some modification on the behavior of the birds through social facilitation. Changes in Numbers of Shorebirds Introduction: N The changes observed in the daily counts of the three common transient species of shorebirds are shown in tables 42, 43, 44. The small number of birds noted would seem to indi­ cate likely sources of error in making counts. Ho\’/ever, the entire shorebird habitat available at O ’Shaughnessy Reservoir could be examined, and an effort was made to account for every bird in the area under observation. Because of the open topography of the O'Shaughnessy Reservoir and the limited amount of mudflats available, it was believed that the majority of the counts in­ cluded every individual present. Habitat and shorebird numbers: Many bird watchers In the Midwest are aware that -92- good numbers of shorebirds depend on the state of devel­ opment of mudflats. Trautman (1940) observed the rapid appearance of shorebirds soon after the development of favorable habitat, and correlates the abundance of fall birds with the amount of feeding territory. The rate of exposure of mudflats and the extent of mudflats present at O ’Shaughnessy Reservoir was a func­ tion of the water level. Figure 3 shows the water levels at O’Shaughnessy Reservoir from July 1 to December 31 of 1952, 1953, and 1954. Table 45 summarizes the water level data for the fall period of 1952. As can be seen from these tables and figure 3, water levels may grad­ ually drop in the fall. This gradual drop in water level exposed a series of mudflats along the shores of the res­ ervoir. The mudflats were all connected by strips of ex­ posed shoreline. This resulted in isolated pockets of shorebird habitat since many of the intervening strips of shoreline were rocky, dry, restricted in area, and presumably low in shorebird food. As the upper reaches of the mudflats dried, new damp areas were being exposed at the lower edges. The general relation between water level and num­ ber of individuals of all species of shorebirds ob­ served can be demonstrated by use of Wheaton Club field -93- notes for O’ShaughnessyReservoir. Table 46 compares the number of individual shorebirds of all species, ex­ cepting killdeer, observed per day by members of the Wheaton Club and this investigator, as compared to the water level at 0*Shaughnessy Reservoir. Killdeer oc­ cupied not only mudflats, but open fields and pastures as well, and the numbers of this species observed per day are relatively independent of raudflat development (see table 47). At Buckeye Lake the situation was ap­ parently otherwise, killdeer numbers being correlated with the number of mudflats (Trautman 1940). The ex­ tent and development of feeding areas undoubtedly in­ fluenced not only the number of sandpipers seen but the length of stopover of some individuals. Figure 7 summarizes in the above fashion the counts of least and semipalmated sandpipers for the years 1948 through 1954 at 0*Shaughnessy Reservoir. As was noted by Trautman (1940) at Buckeye Lake, Ohio, the bulk of the numbers of semipalmated sandpiper is observed slightly after those for least sandpiper. The least sandpiper counts would suffer the most from high water inundating the mudflats early in the season. If high water existed throughout the state, or even throughout the Midwest, during late August and September, we might expect an -94- accelerated migration of least sandpipers through the area, i.e., shorter periods of stopover would occur, unless the loss of mudflat habitat in the various lakes and reservoirs was compensated for by an increase in flooded fields. On the other hand, the semipalmated sandpiper migration might be influenced more by water level changes in September. The water level graph of figure 3 indicates that water levels more often de­ crease in September than August, and are lower in Sep­ tember than August. This would result in more frequent and longer stopovers of semipalmated sandpipers and a consequent decrease in the rate of migration of that species. The importance of water levels in accelera­ ting or retarding shorebird migration could be deter­ mined by adequate censusing of sandpipers along the flight routes and on their wintering grounds. Pectoral Sandpiper: In 1952 when water levels were at their lowest, the counts of pectoral sandpipers at 0*Shaughnessy Reservoir exhibited two peaks, one in August and one in October. In 1954, Nelson Thompson, a member of the Wheaton Club, made observations on a series of shalloxv ponds south of Columbus. The water levels in these ponds remained con­ stant or declined slightly, but a fair amount of habitat -9 5- was available. His data suggest, also, two peaks of ob­ served numbers of pectoral sandpipers. In 1953 water levels at O'Shaughnessy Reservoir were higher than for the same date in 1952, and during July and most of August 1953, no appreciable decrease in water level occurred. Water levels on August 31, 1953 were only slightly below that they were on August 1, 1952. The high peak of pectoral sandpiper numbers observed in August 1952 \vas not noted in 1953, and the total ob­ served population was lov/er in 1953 than in 1952. This seems to correlate with the changes described above in water level, and consequently with the extent and devel­ opment of mudflats. A high number of pectoral sand­ pipers observed in September at Buckeye Lake agrees with the observations by Trautman (1940). Apparently a bimodal population curve does not appear at Buckeye Lake, or perhaps those observed in Franklin County In 1952 and in 1954 are not represent­ ative of the usual situation. Least and Semipalmated Sandpipers: A close correlation also existed between observed numbers of semipalmated and least sandpipers and the extent of mudflats at O*Shaughnessy Reservoir. This can be seen by comparing table 45 and figure 3 with -96-

tables 42, 43, and 44. Tautman found this to be true also at Buckeye Lake. Dunlin: Dunlin counts did not vary with the development of mudflats. The data of table 4S indicate that no great difference existed from 1951 through 1953 in numbers per day of this species. Weather and Shorebird Migration Pectoral Sandpiper: Pectoral sandpipers were seen in the area for a longer time than any other shorebirds except killdeer. Table 47 shows the changes in numbers of pectorals and the general weather pattern of the area. Increase in pectorals seem to occur following the passage of a cold front (see table 50). This was not the case after the weak frontal passage of September 6-7, 1952, and after the active frontal passage of September 15-16, 1952. An increase occurred on October 10-11, when no cold fronts passed through the area, although there -was a change in the weather from clear to cloudy and colder during that time. The disturbance on the 10th was caused by the northward movement of a loiv along the Atlantic Coast, and this resulted In a change of tem­ perature and cloud cover similar to that of a frontal -97- passage. Neither of the increases in 1953 were asso­ ciated with f rontal passage. In 1952 a number of cold fronts moved through dur­ ing the fall; 5 in August, 5 in September, 7 in October, and 6 in November. There is a probability that with this large number of frontal passages almost any changes in pectoral sandpipers populations could be made to math­ ematically correlate in some way to cold fronts. Whether or not the correlations described above are significant would depend on further field and laboratory work. The data of 1953 do indicate that increases can occur in the absence of frontal passage. The observations of October 20 and 21, 1952, may be of significance, for among those of the 20th may be an observation of the start of migration from the area. On the evening of October 20, scattered strato- cumulus clouds covered less than 0.3 of the sky, and the temperature was 4Q C. at 1700 hours and 1/2° C. at 1808 hours. The ifind was from the north and averaged 1155 feet per minute, vd th gusts to 1550. Thirty-five pectoral sandpipers were noted at O'Shaughnessy. Observations began at 1630 hours at area 2. At 1700 hours 15 pectoral sandpipers left the area ob- -98-

servation, and at 1808, 2 more left. These latter in­

dividuals were observed to fly south at an estimated altitude of 120 feet. On the morning of October 21, only 18 pectoral sandpipers could be found at O ’Shaugh­ nessy. The largest feeding area present, that at area 2 was frozen over on the 21st but was open again on the 22nd, when 26 pectoral sandpipers were found in the. area. The decreases in pectoral sandpiper populations seemed to occur during the clearing weather following movement of a front through the area. No relation seemed to exist between temperature or wind velocity and decreases in numbers. Three pectoral sandpipers marked with a black stain appeared at the reservoir in October of 1952. The black stain occupied different parts of each bird, and the extent of the stain varied from bird to bird. This made it possible to recognize these three birdst at least for a time. No other birds with similar staining were seen at the reservoir, and no dilution was noted in the intensity of the stain on the days when these birds were observed. "A"' appeared October 7 and was last seen on October 21. "B" was observed from Octo­ ber 9 to October 22. "C" was seen on 2 days, October 12 and October 13. The data on ”AU indicate that the length of stopover of pectoral sandpipers nay be as much as 14 days. The stopover of these three birds indicated that not all individuals of a species leave an area at the sane tine, and the length of stopover varies from in­ dividual to individual. Least Sandpipers: Data on changes of populations of least sandpipers are presented in table 51. The increases of August 4-5, August 21-22, and September 2-3, 1952 all follow pass­ ages of cold fronts through the area. However, in­ creases of August 23-24 and August 30-31, 1952, are not closely associated with frontal activity. The decreases in numbers did not seem to correlate consistently with any particular type of weather, some occuring under over cast slcies, others under increasingly cloudy skies, and still others during spells of clear skies. A few de­ creases occurred in association with cold front act­ ivity (Sept. 1-2, and Sept. 6-7, 1952). The stopover period of one individual, recognizable because of a leg deformity, is presented in table 51. This bird remained in the area from August 26 through August 30, while other birds were leaving the area, as indicated by the decrease in population from August 27 to 30. -100-

SerJLralaated Sandpiper: The statements regarding changes in numbers of

least sandpipers also apply to semipalmated sandpipers.

Sore increase in numbers of the latter seemed to corre­

late with cold front passages, others did not (see

table 52). The decreases of semipalmated numbers oc­ curred during periods of clear skies (except for those of September 17 and 18). One semipalmated sandpiper, identified by means of an injured leg, was observed from September 7 through September 12, 1952.

Doiwi.tch.er:

On several days in August and September of 1952, a dowitcher was recorded for the reservoir. From August

21 to August 29, a dowitcher was recorded daily in area

8. From September 6 to September 15 a dowitcher was re­ corded on 5 different days at area 2. If the obsera- tiems made in area 8 all pertain to one individual, a stopover of eight days was made by that bird; and, if the records at area 2 were of one individual, those data would represent a stopover of 10 days. Whether or not these records really refer to one individual is pure conjecture, but it is possible that stopover of this length could occur, and it is not likely that many dif­ ferent dowitchers would be seen in Central Ohio in the -101-

fall (see Borror, 1950). Consideration of the length

of stopover of the peep sandpipers, mentioned above, and

the supposed sto over of the dowitcher suggests that weather is not the only factor regulating the rate of migration through an area.

Dunlin: The water level at Q *Shaughnessy during 1951, 1952, and 1953 was below that of many previous years, and dunlins were seen in the years 1951 to 1953 in larger numbers than in former years. Nevertheless, they did not seem to freouent mudflats as much as the other shore­ birds. Dunlins usually fed in the water a foot or so from the edge of the mudflats. Differences in water levels in 1951, 1952, and 1953 were not reflected in the numbers of dunlins observed at 0*Shaughnessy (see table 48), The changes in numbers of dunlins did not appear to be correlated with weather changes (see table 53), and the curves of the frequency of observa­ tion of dunlins for 1951 to 1953 were similar and approached that of a normal curve of distribution (see figure 6), Migration of least sandpipers from the reservoir must have taken place under a variety of weather con­ ditions, but for pectoral? and semipalmated sandpipers and dunlins, decreases occurred under fair weather. These species may move in the high pressure areas with generally northwest winds and clear skies that follow cold fronts. A convenient way to show the long-time trend of sandpiper migration has been described by Hylbon (1950). The census data for each of several years are added to­ gether, so that each daily total represents the sum of several seasons* records. A graph obtained from these totals gives a general picture of a species migration through an area and may be used as a basis for study of yearly fluctuations. Diurnal Activity Introduction: The observations of pectoral, least, semipalmated, and stilt sandpipers, greater and lesser yellow-legs, semipalmated and black-bellied plovers, and dunlin, all regular migrants at O*Shaughnessy, indicated that a def­ inite and predictable pattern of diurnal activity ex­ isted in those species.

7~. In the case of pectoral sandpipers, the freezing of the mudflats in October may have contributed to the initiation of migration.______-103-

To obtain some quantitative measure of diurnal activity data was obtained on such items as frequency and type of call notes, rate of movements, density of flocks, and uniformity of flock action. Among the techniques used to measure shorebird activity was one in which flights were arbitrarily classified into two catagories. Fly-offs. If the birds taking off from one area presumably could not see at the time of take-off the area to wrhich they Ttltimately flew, this flight pattern was termed a Fly-off. In effect fly-offs were: A. Flights made over an obstruction of hills or trees or around a bend in a water area, enroute from one feeding area to another. B. Flights made from feeding areas to distant roosting areas. C. Flights in which the birds disappeared from sight. Thus fly-offs may be separated from shorter feeding flights or alarm flights. Fly-off activity coincided with increased rate of calls and increased uniformity of flock activity. In the definition of fly-off be­ havior there was no intention to imply that it was a goal-directed behavior. The fly-off was defined only in -104-

terms of the end result as apparent to the observe r. 11. Circular flights and disturbance flights. A. Circular flights are those flights in which birds would fly up from a feeding area, circle over the adjacent water or land area and return to the same or contiguous feeding area. Birds often progressed along an expanse of beach by a series of circular flights. B. Disturbance flights were those flights appar­ ently motivated by the appearance of a predator or by human activity. Fly-offs, were chosen as a measure of general ac­ tivity as they represented longer flights to feeding or roosting areas, or possibly migratory movements. The use of fly-offs as a method of obtaining some quantitative data on the general activity of shorebirds seemed warranted, since fly-offs coincided with an in­ creased number of circular flights, an increased number of call notes, and an increased uniformity of action of the birds. The fly-off data are presented as a measure of activity in table 54. This table indicates only those birds observed in fly-offs out of the total of 4740 birds observed, excluding killdeer.8 8^ Frequency of observation in fall migration in 1952 and 1953. in all Ohio areas visited during this project. -105-

Man y birds must have left the area when no observations were being made, and many movements probably occurred at night. Table 54, consequently, does not include the fly- off s that must have occurred when birds left unobserved. Since the time and duration of observation was dic­ tated by the presence and activity of the birds in the area and by the weather, a mathematically random sampling technique was not deemed feasible* Observations were made so that the birds were followed at as many differ­ ent times during the day, and under as many different weather conditions as possible. Table 41 gives the dis­ tribution of the number of hours afield when data were obtained. The bias is against the times in which the greatest number of fly-offs were noted (see figure8). General activity: From 0400 hours to sunrise, shorebirds were found either (1) dispersed throughout the habitat or, (2) moving out from a central roosting area where some of them probably spent the night. In the first situation, birds were observed feeding, preening, displaying, or sleeping. In the second case (movement from a central roosting area) birds would intermingle periods of feeding with fly-offs and circular flights. This resulted in a gradual radiation of the population out from the roosting -106- area. Many fly-offs occurred during this period of morning dispersal from the roost indicating one peak of activity at that time (see figure 8). During the period from sunrise to sunset five types of activity were consistently noted. These activities are arranged below in order of the amount of time de­ voted to each. 1. Feeding 2. Resting 3. Movement from one area to another a. Walking along shoreline while feeding b. Flights (fly-offs, circular flights) 4. Display a. Agressive activity b. Pre-flight activity 5. Response to disturbance Birds were observed to feed continually throughout the day and more time was spent in feeding than in any other activity. In spot checks of flocks feeding in given areas, the size and species composition usually remained constant throughout the day, indicating the possibility that the same birds stayed in one area all day long. There were definite exceptions to this general rule, however. Three pectoral sandpipers were noted with -107- distinctive black stains which made it possible to iden­ tify them. One semipalmated sandpiper and one least sandpiper had leg injuries of a type that made it possible

to recognize them. These individuals were found from one day to the next with groups differing in size and species composition from one day to the next. In addition one in­ dividual, a pectoral sandpiper with conspicuous black under tail coverts, was observed on three separate mud­ flats (all within 1/2 mile of each other) during one cen­ sus of the area. This showed that flock composition was not always constant and also revealed a possible source of error in the daily censuses. Resting or loafing periods were observed to occur at any time during the day. The data do not indicate any relationship between the time or duration of resting and the environmental factors being considered in this re­ port. The method of estimating flock density by meas­ uring distance between individuals in a flock in units of the body length of the birds was applied to shorebirds as well as to ducks (see pages 59-60). The measure­ ments were difficult to obtain for shorebirds, as they were moving about. Some relatively objective informa­ tion was obtained by the use of LA measurements. The -108-

extent of the feeding areas may have had a definite in­ fluence on the distance to which birds could be sep­ arated, and investigations in other areas of the country probably would show that a greater variation in flock density exists. Pectoral sandpipers, while feeding, were observed to be from l/2 to 15 feet apart. In the majority of re­ cords the birds were 3 to 5 feet apart. There seemed to be no relation between flock density and size of groups, time of day, or type of weather. When flying-pectoral sandpipers were closer together; this distance was es­ timated to be between 1/2 and 3 feet. Least and semi­ palmated sandpipers seemed to behave similar to pec­ toral sandpipers in that there was no apparent relation between flock density and the environmental variables considered. Peep and dunlin flocks seemed to be more compact than pectoral flocks. Dunlins in feeding flocks were from l/2 to 12 feet apart, and in a majority of observations were 1 to 3 feet apart. Flock density was (in dunlins and peeps) greater when the birds were in flight. Movement was observed at all hours of the day, the birds usually flying from one mudflat to another. Most movement was noted before sunrise and after sunset, -109-

and this pattern is reflected in the distribution of fly-offs on figure 8. Some flights may have been stim­ ulated by disturbance. Probably the extent and availability of food in­ fluenced the length of time birds remained in one obser­ vation area. If feeding areas were contiguous, birds were often observed progressing from one area to another. In such a situation an observation at one hour would in­ dicate the presence of birds, later at the same location no birds would be found, leading one to believe they had migrated, whereas they actually wandered through adjacent feeding areas to new locations along the same shore. An observation made on September 10, 1952, sug­ gested that the behavior of other birds may stimulate flight and departure from an observation area. Ten stilt sandpipers were being observed as they fed in mud­ flats at Twin Lakes. At 1832 hours three stilt sand­ pipers flew over the area, calling. Five of the stilts on the mudflats began to call, flew up, joined the three newcomers, and the group flew toward the reservoir, tur­ ned north, and disappeared from view. Flights made during the day varied in length. Non­ stop feeding flights between areas on G*Shaughnessy Reservoir were observed to extend up to 4.3 miles (semi- -110- palmated and stilt sandpipers). Aggressive displays occurred in all species ob­ served, but most often in the killdeer. The displays consisted of aggressive movements directed toward one individual, with either a pecking motion or a short chase. The killdeer engage in more elaborate displays which included movements of spread wing and tail. The aggressive displays were never maintained for more than one or two encounters in species other than the killdeer. Certain activities were noted preceding and follow­ ing flights. Preceding flights (those not caused by dis­ turbance) the rate of calling increased, and the birds usually made short flights over the area, only to return to the take-off place. On two occasions preceding fly- offs, flocks of peep sandpipers stopped feeding and the flocks became more compact, i.e. they were less than five LA. In 1952 striking behavior ’was noted in 7 of 12 pec­ toral flocks and in 6 of 9 mixed least and semipalmated sandpipers flocks which had flown into the area under ob­ servation. In these situations, the flocks alighted and the birds stood still, all facing the same direction for five seconds to one minute. Birds which had alighted away from the main body of the flock moved toward the flock and orientated themselves In the same direction as -111-

the rest of the birds. Then all began to feed and dis­ perse over the mudflats. If shorebirds were flushed during the day they us­ ually either flew to an adjacent feeding area, or they returned to the site from which they had been flushed, provided the cause of disturbance had disappeared. Along a continuous beach, shorebirds moved ahead of the observer as he walked along, or they circled around and alighted behind him. The scarcity of such behavior, as pre-flight ac­ tivity, increase in flock density, increase In rate of calling, or roosting behavior, gave the impression that activity during the day, from sunrise to sunset, con­ sisted primarily of constant feeding, broken by resting periods, infrequent flights, and aggressive displays. After sunset, as the light intensity decreased, changes in behavior occurred. The rate of calling in­ creased, circular flights increased, and an increase was noted in the number of birds involved in fly-offs. This resulted in a second peak of diurnal activity as measured by fly-offs, corresponding to the peak observed before sunrise. When the birds were flushed after sunset they usually left the area of observation and were not obser­ ved to return during the remaining daylight hours. -112-

Fly-offs before sunrise occurred at lower light in­ tensities than did the same activity in the evening. On some nights the birds were found scattered throughout the area much as they were in the diurnal period. On other nights birds were observed flying from several feeding areas to one locale. Here they gathered, and a number were later detected as they roosted on the mudflats. Other birds were observed flying out of the area of observation after arriving at this roosting area. Whether or not the roosting birds remained at the central area or flew off later during the night was not deter­ mined. The activity of shorebirds was not observed to be directly influenced by air temperatures, or by the amount and duration of precipitation. Wind speed, likewise, had no perceptible effect on activity, though flight against winds appeared more labored and slower as the wind speeds increased. Ply-off Activity: Figure 8 shows the relation between time of day and shorebird activity using the fly-off as a measure of act- vity. The least and semipalmated sandpipers were active before they could be seen by early morning light, thus figure 8 shows only an evening peak of activity for these -113-

tv,-o peeps. The pectoral sandpipers and dunlins followed the bimodal curve of figure 8. Figure 9 indicates the relation between light in­ tensity and fly-offs during a given range of light in­ tensity. The 100 foot-candle level xvas selected because the preponderence of activity took place at this or loit­ er light levels. A light intensity of 100 foot-candles was recorded only after 1715 hours and before 0630 hours in the course of this part of the study. As the inves­ tigation of shorebird activity was part of the larger program, a disproportionate amount of observations was made at a time other than that which was optimum for ob­ serving the evening and morning peaks of activity. This further emphasizes the preponderence of activity that took place below 100 foot-candles. Of the fly-offs occurring above 100 foot-candles, 64 per cent occurred when the sky was 80 to 100 per cent overcast. Five-hundred and five birds were noted in fly-offs ('The remainder of the birds migrated from the area at times when observations were not being made). Figure 10 shows the routes taken by shorebirds in the fly-offs observed during 1952 at O ’Shaughnessy Reservoir. Similar routes were folloived in 1953. In the majority of the flights the birds flew over the ’water -114-

and followed the path of the shoreline. In these flights leading overland, the birds apparently were moving to­ ward feeding areas on the reservoir. LABORATORY TESTS Introduction The close correlation noted in the field between light intensity and the activity of ducks suggested that light was a significant variable in the environment of those birds. This idea is not new, but a more definite idea of the part light plays in affecting duck behavior was needed. The following questions were posed: (1) Can changes in light intensity initiate activity of ducks, and (2) Can changes in light intensity modify the activity of ducks? The observations in the field provided a descrip­ tion of responses which seemed to be correlated with changing light intensity. These responses were: Move­ ment back and forth and on the water, anticipatory move­ ments (head jerking), and flight. The field observations also provided a sample of these responses in the pop­ ulation, and the data indicated that the responses were widespread, i.e. most individuals exhibited them. Con­ sequently, the number of ducks submitted to laboratory -115-

tests was not of major importance. If these responses can be obtained from one bird, with light as the sole variable, that test will be significant as to cause and effect, though not to degree of Influence of light. Some refinement could be obtained if ducks were used that were genetically wild, but raised from the egg in cap­ tivity. Then if learning is a factor, use of such birds would indicate that the learning is not from experienced wild ducks. With the foregoing in mind, a series of laboratory tests was designed to provided information on the results of changing light intensity on waterfowl activity. Equipment A steel chamber, (see figure 17) 140 inches long by 111 inches wide by 70 inches high (formerly a fum­ igating chamber for Insect collections), was modified in the following manner: 1. A light box containing 9 to 12 lights of vary­ ing sizes was installed inside on the roof of the cham- er. This box was of frosted plastic. The light in­ tensities used are shown in f igures 11 and 12. 2. A door containing a window of one-way glass re­ placed the metal door of the chamber. When the light intensity in the observation room was lower than that -116-

in the chamber, the one-x^ay glass permitted observa­ tion into, but not out of, the chamber. 3. The floor of the chamber was covered xvith fine sand. This xvas dark sand in the 1954 tests and light in the 1955 tests. Strips of tape were laid over this sand so that a series of lines divided the chamber floor into a number of sruares each 24 inches on a side. 4. A light baffle was built around the observation window so that any stray light in the observation room ’would not reveal the investigator, xvho was stationed between the light baffle and the observation window. 5. A thermometer was placed in the chamber and was visible from the observation post. 6. Light and dark periods were controlled by two electric timers in the observation room, thus a con­ stant photoperiod could be maintained. The room in which the chamber was located con­ tained a thermostatically controlled heater, so that constant temperatures could be maintained. This was effective only so long as the outside air temperature o remained below 21 C., for below that the heater could raise the room temperature and maintain it within 1° C. There was no way, however, to reduce temperatures when the room heated above 21° C. in the late spring and -117- sumraer. A strong fan and air ducts leading into the ceil­ ing of the chamber could be used to introduce air into the chamber from outside the building, or to remove air from the chamber and draw new air from the observation room. A panel in the observation room provided controls for light intensity in the chamber. Each light in the light box could be switched off or on by means of a knife switch on the control panel. A rheostat was not used to change light intensities since it was desirable to be able to duplicate, in succeeding tests, a given light intensity and also to insure that the rate of de­ crease of light xvas identical from test to test. The chamber was not sound proof, which introduced a source of error. However, the ducks apparently quickly conditioned to the multitude of sounds outside the building, and sound could be reduced to a minimum in the observation room. The knife switches were silent in operation, and the investigator sat quietly during the observation periods. If any noise was made during the conduct of the test, or any outside noise seemed to produce a response in the ducks, this was noted on the -118-

observation sheets. Methods Ducks were introduced into the chamber and left there throughout an entire test period. Food and water were changed daily, and at feeding time fecal matter and scattered grain were removed by sifting the material out of the sand. At feeding time the blower was turned on and fresh air was brought into the chamber from the outside. The same amount of food was introduced each day and a record was kept of the amount of food remain­ ing from the previous feeding. The food used through­ out the experiements was a mixture of scratch food and conditioner on ivhich the birds had been raised. In the first tests food was'left in the chamber for one hour, then any left over was removed and weighed. The alternate light and dark periods were each 12 hours in length. Observations started near the end of the 12 hour photoperiod, before the set time for the lights to go off. Lights were turned off one by one and the activity of each duck was measured at the given light intensity. Each light remained off for a certain length of time before the next light was turned off. The result was a stair-step decrease in light intensity (see figure 12 and 13). The activity of each duck was -119- measured by counting the number of lines (formed by the strips of tape) it crossed during each level of light intensity. Because the field observations were made on groups of birds, the tests were conducted on groups of birds, so that the effects due to social facilitation would not be lost. Most of the tests were run on five mallard drakes collectively. These birds were incubator hatched from eggs collected in the wild, and were reared in captivity, together with two hen mallards and a pair of wood ducks. The same five birds were used for all three tests. Since hunger stimuli were considered as possible factors modifying responses to light intensity, an ex­ periment (designated at test I, series 1) was conducted to measure the effects of food deprivation on responses to changing light intensity. In this first experiment, the ducks exhibited such variation in response on successive days that further experiments were designed in an attempt to discover factors responsible for this variation. Accordingly, experiments designated as series 2, 3, 4, and 5 of test I were set up not to de­ termine the effect of hunger on responses to light, but rather to see if standard levels of response could be -120-

established (see table 55 for record of proceedure). In all of test I temperature fluctuations paral­ leled those outside, except for those days with tempera- o tures below 10 C. in which case the thermostatically controlled heater maintained the chamber temperature at 10° C. The ducks were individually marked with plastic markers, and were first introduced into the test chamber on February 24, 1954. They were observed several times a day for two weeks before any tests were made. During the fourteen-day pretest period the times of observation varied at random. The amount of food that the ducks would eat was determined during this period, and sub­ sequent feedings were just below that level. Apparently the ducks were not completely conditioned to the situa­ tion for they did not feed on three of the test days. No conditioning period longer than one day preceded any of the succeeding series of tests. Tests began 50 minutes before the end of the 12 hour photoperiod. Actually, the investigator entered the main roon 10 minutes before the start of the test period to quietly station himself at the observation window. A record was kept of the activity in the 5 minutes -121-

preceding the first decrease in light intensity in the chamber. This 5-minute period marked the start of the regular observation period, and the data obtained were included in the analyses. After this preliminary per­ iod the lights were turned off, one every 5 minutes, un­ til all of the lights were off. The general curve of the decrease in light intensity approximated that observed after sunset in the field (see figures 12, 13, 14), though the intensities were not comparable. In series 3, on those days when lights were turned off before the end of the 12 hour photoperiod, the entire bank of lights was switched on at the conclusion of the observation period, and the remaining hours of the photo­ period continued as usual. Consequently, the ducks had a 12 hour light period, but with a 45 minute span of de­ creasing light intensity occurring somewhere in the photoperiod. In some of the experiments a few addi­ tional observations were made during the period when there was no change in light intensity (see table 55). Test II was made in 1955 in a further attempt to ascertain the degree of influence of changing light in­ tensity on activity. The same five drake mallards used in test 1 were used in this test, as a rough measure of the variability of their response had already been ob­ -122-

tained. The birds were introduced into the chamber on January 2, 1955, and tests commenced on January 3, 1955. In test II temperature, feeding time, amount and kind of food, and time of observation remained constant. Ob­ servations with decreasing light intensity were made only on alternate nights, so that a comparison could be made of activity at similar times in the photoperiod un­ der either stable or changing light intensity. In test II, 12 lights were used, and a 3-minute observation per­ iod was maintained between changes of light intensity. The observations began 36 minutes before the end of the 12-hour phptoperiod (see table 58)* If the ducks were left in the chamber between series of a test, feeding was done in the middle of the photo­ period, and the photoperiod was regulated by the electric timers. Observations The information obtained in tests 1 and test 11 is presented in tables 57, 58, and figures 14, 15, 16. Associated with the higher activity was an in­ creasing rate of movement followed by repeated and rapid upxvard head jerking. This activity usually culminated in flight. This was a response similar to that observed in the field at the time of evening flight. -123-

Figures 14, 15, 16, indicate that there is a rela­ tion between changing light intensity and increased act­ ivity of mallards. The results of test I indicate that increased activity can be initiated by lowering light intensity. However, in test II, increased activity occurred whether or not light intensity was changed. Movements increased, the anticipatory head jerking was made, and flight took place on evenings when light inten­ sity was not lowered during the observation period. When light intensity was decreased, though, the total amount of activity was higher. Moreover, the increase in activity was roughly proportional to the decrease in light intensity. Flight was noted only once during the day. This was observed on April 12, 1954 after the investigator had entered the main room at 1030 hours preparatory to feeding the birds. From May 18, 1954 through May 21, 1954, one mallard drake was tested in the chamber (Test I, series 5). This bird was one of the five previously tested during the spring, and thus, may have been conditioned to the test­ ing procedure. On the 18th and 19th of May the bird was very active in the 10-minute period preceding the regular observation time. On the 18th the bird exhibited typical -124- preflight activity and flew. This occurred twice in that 10-minute period. On the 19th, this again occurred, and the bird flew once. On the bases of tests I and II, changing light in­ tensity may be said to have initiated some forms of in­ creased activity, but since these responses also appeared independently of changes in light, some additional stimuli were involved. Light decreases did result in increased movement about the chamber, and the decrease in light in­ tensity seeised to regulate the rate of change of the act­ ivity so that the latter reached a peak at the time of the lowest light intensity. Analysis of Results Even under apparently standard conditions the amount of activity of the ducks during the tests varied widely from day to day. Factors which may have been respon­ sible for this variation (and which might have been re­ sponsible for the activity under constant light intensity are: 1. Insufficient time for the birds to condition to the test situation. The responses might have been evoked by factors of the test situation, i.e., the chamber environment. As an example, ducks always slept at the end of the chamber -125-

opposite the door, and only in movements which usually culminated in flight did they move near the door. 2. Variation in food consumption (see table 59). This might have been influenced by 1, above, below, or by differences in the amount of act­ ivity previous to feeding time, 3. Changing temperature (see table 59). 4. Noise from the outside of the chamber. The only response that could definitely be attrib­ uted to sound was a sudden cessation of act­ ivity. This response xvas noted only to noises made in the observation room. Other responses to sound could have been made and not noticed. The inevitable noises made by the investigator entering or leaving the main room at feeding time and prior to tests could have stimulated activity. 5. Changing thresholds of response to absolute light intensity. The light intensity of the regular photoperiod might have been low enough to stimulate movement in the evening, if the threshold to light intensity was lowered. This might have been due to the facilitation effects -126-

of the other factors discussed here, or it might have been due to a hormonal change, or cyclic activity of the gastro-intestinal tract. 6. Fatigue of other responses. As the birds were under near constant conditions of light, tem­ perature, and visual cties, responses induced by those factors might have become fatigued. This might have led to movement, as a type of dis­ placement activity. If this was the case, changing light intensity several times a day, or once earlier in the day might eliminate the late evening activity that appeared at the end of a stable photoperiod. 7. Learning. What role learning played in the be­ havior of ducks in this test situation was not known. The decreased response to the lowest light intensities of test II on January 10, and 12, may be due to learning. At the con­ clusion of the daily observations, it was nec­ essary to reset the control panel and check the timers. This made some noise in the main room. The ducks could have become conditioned to the combination of low intensity followed by noise in the room. -127-

8. Onset of breeding behavior. It was necessary to remove the ducks from the chamber from March 20 to April 6, 1954. This was done while the sand in the chamber was being cleaned. The ducks were placed in an outside pen, separate from two hen mallards, but in view of them. The longer photoperiod, plus the day length in­ crement, and the proximity of hens seemed to facilitate breeding behavior in the drakes. On April 27, 1954, while in the chamber, the other drakes attempted copulation with one male, tagged as ,TBarn. These attempts were observed every day through May 3, 1954. ’’Bar1' was removed from the chamber on that date. Some of the attempts at copulation resulted in increased movement about the chamber. 9. Foul air. Until the sand was cleaned on March 21, 1954, flight of the ducks stirred up con­ siderable dust which may have resulted in some change in their response. Yet, when dustless sand was used in 1955, variations in amount of activity still appeared. 10. Method of changing light intensity, If this were the only factor, variations in activity should be -128-

slight at constant light intensities, which was not the case. No clear relation was noted between activity and temperature or food deprivation. The data indicated that if a relation existed between temperature and amount of activity, it was a complex one, and the in­ formation provided by these tests was not sufficient to warrant drawing inferences (see table 59). Future experimentation of this type demands a soundproof chamber, or the use of masking sounds, long periods of conditioning, and rheostatic regulation of light intensity from a single light source. Automatic methods of feeding and watering should be developed. Testing procedures should be set up to clarify the re­ lative importance of the 10 factors discussed above. DISCUSSION Food Supply Data presented in the section dealing \vith mallards indicate that some migrant mallards and black ducks as­ sociated with the zoo flock and partook of food provided for the latter by personnel of the zoo. The migration of these birds may have been interrupted temporarily by the presence of the easily available food supply. The extent of this interruption probably depended on the -129- ducksf length of stopover at the reservoir and whatever previous conditioning they may have had to artificial f eeding. At Horse Shoe Lake in Illinois concentrations of Canada geese have resulted from the creation of a win­ ter feeding area. These geese formerly wintered along the Mississippi River and the Gulf Coast. Other simi­ lar concentrations have been caused in Ontario, Wis­ consin, Missouri, and Minnesota (Elder, 1946). Artifical feeding or the presence of an avail­ able food supply of grain may be considered important with regard to migration. The largest decreases in mallards and black ducks at O ’Shaughnessy Reservoir, however, took place when plentiful food supplies were apparently still available (Bob Winner, personal com­ munication). Girard (1941) found that winter feeding of mallards in Montana did not lead more birds to stay. A decrease in pectoral sandpipers was noted after October 21, 1952, when the mudflats had frozen over, indicating that immediate availability of food may be an important factor in the migration of this species. Weather and Decreases in Numbers Some decreases in counts of black ducks occurred during periods of clear skies, others during overcast -130-

nights, some with cold fronts, and others during periods of relatively stable weather conditions. Apparently adverse weather is not a necessary stimulus to migra­ tion of black ducks. The findings suggest that the de­ parture of duclcs from the area resulted from a com­ bination of environmental factors differing in their effectiveness from time to time according to internal changes in the birds, though other factors may have been involved that were not measured in the course of this study. Notable changes in the duck population at O'Shaugh- nessy took place as the reservoir froze over. Hochbaum (1944) mentions that at Delta, gatherings of mallards dwindle only when the shore is closed by ice. The freeze over at O ’Shaughnessy is gradual and so is the decline in numbers of black ducks. The correlation between increases of black ducks on O ’Shaughnessy and cold fronts may actually be a correl­ ation between the freezing of areas north of the reservoir and a subsequent movement of birds into the area. In all the shorebird species and in the black ducks and mallards, decreases occurred gradually and, excepting pectoral and semipalmated sandpipers, occurred under vary­ ing weather conditions* -131-

A fairly consistent relation was noted between weather and changes in pectoral sandpiper populations. The increases have already been discussed on page 96. The decreases were noted during periods of clear skies following the passage of a cold front. Thompson (1953) believes it possible that the clear skies and light winds commonly associated with frontal passage are more important than the actual atmospheric pressure. Ball (1952) noted nuthatch and thrush flights occurred most often in fair weather. For the most part, semipalmated sandpiper decreases also seemed to occur during fair weather, but least sandpiper decreases could not be correlated with clear skies and light winds of fair weather. A gradual decrease in numbers may be a regular feature of the departure of birds from an area. Both Bennett (1952), and Dennis (1954) refer to the gradual departure of birds from an area. Dennis comments: "After a peak has been reached, num­ bers declined steadily on each succeed­ ing day of favorable weather." (Dennis, 1954; p. 107). Gradual decreases in numbers of transient birds in an area may occur more often than has been suspected; the data in the literature on this are scanty. Instances -132-

when species suddenly and completely departed from an area may be difficult to find, unless the observation is of a large flight of migrants passing through or over an area. Even in the big "waves" birds may not pass through all at once. Bagg (1950, p. 7) reports an observation by Batchelder on a ’’tidal wave" of migrants, "Before noon of that day most of the birds have passed on, but for a day or two after­ wards the number of loiterers was sufficient to be noticeable...." If most decreases are gradual as suspected, then the in­ ference may be drawn that precisely when a migratory flight is made depends on the respective state of the individual bird. Ball expresses this idea clearly when he observes: "During the first few weeks of the fall migration season birds that are nearly or completely conditioned to begin their southward flight are subjected to differ­ ent intensities of meterological factors. Some individuals may have higher thresh- holds than others to these factors or stimuli. It has been shown above that, with respect to the initiation of flights generalizing as to efficacy of wind, rain, cloudiness, pressure and temperature Is unwise - almost iiaDossible." (Ball, 1952; p. 109). The variation in response of individual birds may be no­ ted especially in the differential departure dates of banded birds, and also in the case of the naturally -133- marked sandpipers at O ’Shaughnessy wherein one individual bird persisted in an area while another arrived and de­ parted. Dennis (1954) notes that in general, departures of passerines in the spring were made during periods of rising temperatures when the wind was in a favorable quarter. The decreases of pectoral sandpipers may be an ex­ ample of a similar situation wherein the stimulus is more or less constant and response depends on the re­ ceptiveness of the bird. That the stimulus situations need not be constant has been considered by Ball: ’’The actual stimulus to depart may not be specific: to a bird prepared for migration any one of several releasers may set it in motion. Hunger, exhilaration at the term­ ination of a passing storm, a sudden gust of xvind, or other disturbance may tip the balance.” (Ball, 1952: p. 190). The observed gradual departure of birds from an area may reflect, therefore, the variability in receptiveness to several stimuli situations. If this is true, as it seemed to be with the birds observed at O*Shaughnessy as \*/ell as with those studied by Ball, then perhaps to this can be attributed much of the present confusion in the literature. Observations of the same species may be made under different circumstances of stimulus-threshold -134- level complexes, and the correlations between different observations may be hard to analyze. Diurnal Activity Except for the morning and evening feeding flights, the diurnal activity of mallards and black ducks was ob­ served to be a heterogeneous mixture of sleeping, court­ ing, bathing, preening, feeding, and response to disturb­ ance by humans or predators. A similar observation on the mallard was made by Girard. He notes: f,The writer had anticipated that these observations would indicate something of a daily routine for the mallard but the opposite seems to be the case.” (Girard, 1941; p. 249). A mingling of various activities served as the diurnal pattern for the shorebirds observed at the reservoir. Wind and Behavior Certain weather factors brought about noticeable changes in the behavior of the observed species. Among the many authors who have considered bird migration, there is a more or less general agreement that wind velocity is an important factor in the behavior of birds. Unlike the shorebirds, which did not seem to modify their behavior to an appreciable amount because of wind, the ducks in certain situations responded to wind velocity by heading into the ivind. This was most apparent when -135- the ducks were resting on the water. Other stimuli can modify this response to wind, as evidenced by the posi­ tion of ducks resting on shore; position seemed to be a compromise between facing into the wind and facing to­ ward the water. A further mod if action was shown by the persistent orientation of the ducks at the zoo toward the feeding area. Ducks on the water would not neces­ sarily face the wind if they were feeding or courting, or if they were swimming up or down the reservoir. The activity of both ducks and shorebirds may have been modified with respect to wind direction, but the data are not sufficient for correlation to be made. The point may be emphasized, however, that the activities of ducks and shorebirds on the reservoir occurred relatively independently of the wind, except for loafing or sleeping birds on the water, and that other stimuli may result in ducks actually orienting away from the wind. Svardson (1953) noted that only ducks regularly flew in strong tailwinds during migration. No relation was noted be­ tween wind velocity and the ultimate direction of even­ ing flights of ducks and shorebirds. Wind velocity (un­ less wind speed is high) may not appreciably influence the activity of these birds, and thus, may not be an im­ portant factor in their migration. With less strong -136- flyers (the small passerines for example), wind is prob­ ably an important factor. Peaks of Activity An aspect of migration difficult to measure quanti­ tatively is the various levels of diurnal activity of a bird. Many investigators have measured the movements of caged birds in an attempt to record activity; their findings will be discussed later. In a field situation certain criteria can be taken to indicate changes in activity level. In this study, increased movement on the water of black ducks and mallards, or their flight to feeding areas, was taken as indicative of increased activity. The flyoff was established as a criterion for increased activity in shorebirds. All of the movement on the water (see page 54) that was considered significant occurred on overcast or nearly overcast days, and a majority of the fly-offs of shorebirds taking place above 100 foot-candles occurred on overcase or near over­ cast days. This suggested a relation between activity and light intensity. Diurnal activity of black ducks and mallards as measured by flights, and diurnal activ­ ity of shorebirds as measured by fly-offs, reached tvjro peaks, one early in the morning, the other late in the evening. This is not surprising, for any person who has -137- gone afield can find this to be true of birds in general. The presence of two peaks of diurnal activity in the migration of shorebirds has been pointed out by Svardson (1950). A relation may exist between the evening and morn­ ing preponderance of fly-offs and the time of daily mi­ gration of shorebirds. Since the fly-offs included known roosting flights and feeding flights as well as migratory flights and since those flights which led to migration could not always be determined with certainty, some of the stimulus situations observed may not be responsible for migration and this must be kept in mind throughout the discussion. Since the majority of fly-offs occurred near sun­ rise or sunset regardless of temperature, wind or cloud cover, the following factors, or combinations thereof, may be responsible for fly-offs. 1. Time of sunset or sunrise 2. Absolute light intensity 3. Length of day or night 4. Hunger stimuli 5. Variations in internal physiology 6. Change in social facilitation 7. Changing light intensity -138-

1. The actual time of sunrise or sunset was prob­ ably not a factor. Birds could be observed in fly-offs before sunrise, and the evening fly-offs of a given species might occur at sunset or two hours after sunset on successive evenings. The time of sunset or sunrise, of course, does determine in part the change of light intensity in early morning and late evening. The amount of cloud cover is also a factor in regulating light in­ tensity. 2. The variation in the relation between fly-offs and absolute light intensity suggests that the latter is not the stimulus to flight, but rather that changing light intensity at low levels of light may be. 3. Length of day or night may be important in con­ junction with certain other factors. The length of either period may affect the threshold of response of the shorebirds to a factor sttch as changing light intensity. 4. On long nights hunger stimuli may facilitate re­ sponses to early morning light. Hunger stimuli were con­ sidered by Seibert (1954) to be important in inducing morning flight of sereons from a roost. The birds left the roost at a loiter light intensity in the morning than that at which they rettirned in the evening. A hunger -139-

drive superimposed on the light stimulus caused the birds to leave early in the morning, whereas with full stomachs they responded to higher light intensities in the after­ noon. A similar situation may prevail in the shorebirds at O ’Shaughnessy, although it was known that some shore­ birds fed at night, at least on moonlight nights. 5. Length of night may be important if dark adapt­ ation occurs which makes the bird*s eyes more sensitive to light and results in a response at very low light in­ tensities in the morning. If length of day is the factor responsible for fly-offs, then the exact time of flight may depend on internal physiological changes. As the day progresses, some physiological change may become stim­ ulatory around sunset time. The relationship between the fly-off activity and changing light intensity suggests that, although infernal changes may be involved, the cue leading to the fly-off at a particular time is external. If the stimulus for flight is exclusively internal, it might be thought of as comparable to the vacuum activity as described by Tinbergen (1952). This interpretation is not supported by present day physiology (see page 162.), and it Is doubtful if Tinbergen would consider the type of diurnal rhythm under discussion here as one occurring exclusive of environmental changes (Tinbergen, o d . bit.). -140-

6 and 7. In each instance where fly-offs were ob­ served to occur below 100 foot-candles, the behavior of the birds indicated that so: e specific level of envi­ ronmental change was a stimulus. As light decreased the birds’ social activity increased. Concomitantly, there was a sudden departure of a group of birds of the same or closely related species from the observation area. If a single environmental factor which does not release a certain activity can facilitate neural response, then a number of factors can interact to produce a response. (as demonstrated by the change In time of evening flight of mallards and black ducks in relation to the number of birds present). In the case of the activity of shore­ birds, flight response may be facilitated by one or all of the following: period of food deprivation, length of feeding period, number of previous disturbances by pre­ dators during the day, relative change in light intensity, and social facilitation. The response may be due to a change in the environment, but the threshold level may vary according to the degree of facilitation. Thus in shorebirds the evening and morning flights may be a re­ sponse elicited by a definite light intensity or a cer­ tain relative level of light intensity, but the critical point depends on the degree of social facilitation, in­ -141- cluding such things as the number of birds in the flock, or the activity of associated individuals. Evening and Morning Flights - Preflight Activity The evening and morning flights of ducks have been observed in many sections of the country. Reference has already been made to mallard flights in Manitoba (Hoch- baum, 1944). A detailed description of evening flights of mallards was given by Girard (1941), and descrip­ tions of the evening flight of diving ducks has been made by Brackbill (1952). Girard^ description of the mallard flights agrees with the observations at O'Shaughnessy. He also mentions that: "Before leaving in large flights, the mallards bunch together, a great deal of chattering takes place, and the largest flight leaves between 3:00 and 6:00-p.m." (Girard, 1941; p. 247). This preflight activity noted by Girard is similar to the preflight activity observed at 0*Shaughnessy and described on pages 65-69. In both shorebirds and ducks the exact form and sequence of the preflight activities varied from day to day, but the general increase in ac­ tivity was predictable. Shorebirds made circular flights, and the rate of calling increased. No definite number of circular flights occurred prior to fly-off, and in some cases no circular flights at all were noted prior to fly- -142-

off. Only in a few instances did flock density increase. Black ducks and mallards moved about on the water, and flock density increased prior to take-off; the latter was heralded by the head jerking. These movements did not occur in any fixed pattern, i.e., the direction and extent of movement varied as did the per cent of the ducks engaged in them at any one instance. Miskimen has suggested that flock activity preceding flight was a ritual which had a predictable sequence of steps; how­ ever, the heterogeneous sequence of activity noted in this study did not support her contention. Miskimen also hypothesized that the degree of flock coordination pro­ vided the stimulus to flight. Emlen (1952) has noted a series of physical environmental factors (low temperature, drought, and low light intensity) which promote flocking. Miskimen (1952) notes that flocking reactions were strength­ ened by changes in light intensity, cloud coverage, wind velocity, precipitation, and the presence of predators. She also notes a correlation between the size of the flock and flocking reactions. In the present study wind velocity, temperature, and degree of cloud cover did not seem to be correlated with increased flock density, though the frequency and -143-

extent of flock movement on the water seemed to be greatest on overcast or near overcast days. One ob­ servation indicated that flock density may increase dur­ ing a period of heavy precipitation. The size of the flock may have had some relation to flock density, al­ though no definite correlation was shown by the LA meth­ od. Due to the size of the available water area some restriction may have been placed on spacing of larger flocks of ducks. Use of the LA method (see page 59) did not disclose any consistent difference in disturbed and non-disturbed groups, but occasions were noted when flock density did increase after disturbance. These have been discussed above (page 61). Because there is apparently some disagreement about the effects of wind, cloud cover, flock size, and pre­ cipitation on flock density, particularly of ducks, this aspect of bird behavior needs further investigation. There is no disagreement about a correlation be­ tween decreasing light intensity and flock density. Both Emlen (1952) and Miskimen (1952) describe increases in flock density with decreasing light intensity, and a similar correlation was noted involving flocks of black ducks and mallards during the course of this study. An -144-

increase in flock density, accompanied by an increase in the rate of movement on the water, preceded the evening flights of black ducks and mallards. Evening and Morning Flights - Flight Initiation There may be a relation between evening and morn­ ing flights of black ducks and mallards and migration. Svardson (1952) noted that the peak number of mallards passing the Ottenby bird station during the day occurred at 0600 to 0700 hours and at 1800 to 1900 hours. These are also the times when the greatest number of feeding flights were observed at 0*Shaughnessy. The correlations noted on page 75 suggest that ex­ ternal factors responsible for the evening flights of black ducks and mallards at O*Shaughnessy are light in­ tensity, degree of overcast, and the number of ducks present. The data presented on a few species of diving ducks also suggest that light intensity is a factor in initiating evening flights and that the critical level varies from species to species. A similar situation was noted by Brackbill (1952). No correlation was noted between temperature and wind velocity and the departure times of evening flights at O fShaughnessy* Again, this is in agreement with Brackbill (op. cit.). Girard (1941) noted that the feeding flights of mallards were altered in winter. When a frozen crnst of snow covered the grain fields, the birds remained on the water throughout the night and the forenoon. He does not describe the stimulus situation which kept the ducks on the water during these times. Stimuli for this must have existed, otherwise the birds would have made fruitless flights to the grain fields. Perhaps conditioning in previous ^*/inters was responsible for the birds* behavior. If so, what ivas the conditioned stimulus? It might have been water or air temperature, visual cues, or perhaps the condition of the shore sub­ strate where the birds rested. Girard (op. cit.) also noticed a shift of feeding time during the hunting sea­ son such that the movements then occurred before and aft­ er shooting hours. A shift of flight time during the hunting season was not noted at O*Shaughnessy. Girard also observed that the mallards fed in the grain fields at night. This i^as not known to happen at 0*Shaughnessy. There, birds could be detected returning to the reser­ voir within a half hour after the last group had taken flight. The diving ducks apparently roosted on the main part of the reservoir during the night. Some birds may have returned to the feeding areas undetected because of the difficulty of making observations at night. -146-

Hochbaun (1944) noted that flights were made to feed­ ing grounds all through the day but were concentrated in early morning and late evening. The differences between I-Iochbaum’s observations in Manitoba, Girard’s in Montana, and those made at O ’Shaughnessy Reservoir suggest that evening flight be­ havior can be modified considerably by local situations. Light intensity changes seem to be a factor common to the evening flights in all of these areas. Breckenridge (1953) mentioned light as a factor stimulating flights to roosting rafts by golden eye ducks. lie observed that birds did not arrive at the raft site markedly earlier on cloudy days than on overcast days. He infers that the flights are initiated by variations of light at low in­ tensities. Drost (1931) in Europe considers that light intensity determines the daily departure time of birds. On the basis of the field data a hypothesis can be made concerning the factors involved in evening flight. A schematic diagram of this hypothesis follows: Light intensity —— Degree of overcast Flight Flock intensity and movement (The arrows lead from the factor to that which it in­ fluences) -147-

If this latter hypothesis is correct, then isolated birds would not make evening flights, or would not join in migratory movements. The results of laboratory tests in which a single mallard was used indicated that in­ creased activity and flight could occur in the absence of other mallards. In this species, therefore, flock act­ ivity does not seem to be a necessary stimulus to even­ ing activity and flight* The laboratory tests showed that decreasing light intensity resulted in increased activity of mallards, and that this increase in activity was inversely pro­ portional to the absolute light intensity. Flight and increased activity also occurred on days and at times when there was no change in light intensity. The num­ ber of flights and the amount of activity was higher, on the average, when light intensity was decreased than it was when no changes in light occurred. From the results of these tests it n/ould appear that other factors be­ sides light intensity will bring about increased act­ ivity. Nocturnal Activity In the field, morning and evening peaks of activ­ ity of various species may be correlated with a number of external factors which are also changing at that time. -148-

For example, cyclic flucuations in light, temperature, and wind speed, which are due to the 24-hour cycle of day and night, could be stimuli for evening and morning flights or peaks of activity. Nocturnal activity, like­ wise, could be correlated \tfith changing environmental situations of the early night hours. In a laboratory set up where a cycle of day and night is maintained without changes in temperature or without twilight, the stimuli that may be responsible for increased activity are less obvious. Investigations of cyclic peaks of activity appearing under laboratory conditions have been reviewed by Palmgren (1949), van Oordt (1943), Stein- bacher (1951), Farner (1950) and Eyster (1954). In captivity, migratory species of passerines de­ velop periods of increased activity (Zugunruhe) during the migratory season. Zugunruhe is most characteristic of nocturnal migrants. "The Zugunruhe of these species is mani­ fested most characteristically by a period of pronounced activity between evening and midnight; however, some individuals may show a period of relatively intense activity shortly before dawn, whereas others may be almost continually active throughout the night." (Farner, 1954; p. 148). Zugunruhe has not been noted in non-passerines. Birds under observation in the laboratory typically -149-

exhibited two peaks of activity during the photoperiod. These peaks occurred (1) after the beginning of the photoperiod, and (2) near the end of the photoperiod. These two peaks have been noted in both migratory and non-migratory species. Palmgren (1943) has noted in many instances that a decrease of day-time activity precedes by several days the first night activity. Palmgren (1943, 1944) also reports an increase in diurnal activity in finches during the migratory season; this was, however, not observed by Eyster (1954). The relation of Zugunruhe (nocturnal activity to mi­ gration in caged birds is based on the following correla­ tions). 1. Zugunruhe thus far has been demonstrated only in migratory species; non-migratory species remain relatively quiet at night. 2. The onset of Zugunruhe appears only during the migratory season; in spring it has been noted to extend beyond the usual migratory season to the beginning of the postnuptial molt. 3. Zugunruhe appears to reach its peak at the times during the night when some observers believe nocturnal migration reaches a peak. The first two points are well established, but some -150- questions may be raised about the third correlation. In species in which Zugunruhe reaches a peak before mid­ night (song thrush, Siivonen, 1936; white-crowned and white-throated sparrows, Eyster, 1954) it has been assumed that this peak occurs at the time of the peak of nocturnal migration. In evidence of this, two refer­ ences have been cited in papers concerned with this re­ lation. One citation, from Siivonen C1936), is based on the number of call notes of song and red thrush heard in 10 minute periods at Helsingfors during some fall nights. Application of these findings to other species should be done with care. The other citation is to Lowery (1951). He calculates a maximum flight density of birds in nocturnal flight as occurring between 2300 hours and 2400 hours. The methods used in determing the criterion of flight density are open to question, and the nocturnal observations do not distinguish between species,? Even in the same species the time of the peaks of Zugunruhe may vary. Eyster (1954) noted that accord­ ing to the individual bird, peaks appeared in juncos either twice a night, at 0200 hours and 0500-0600 hours, or once a night, at 2400 hours; in the case of white- throated sparrows peaks appeared at 0300-0400, or at 2400-0600 hours; with white-crowned sparrows peaks -151-

occurred at 2300-2400, or at 2300 hours. One bird ex­ hibited peaks of Zugunruhe at different times in dif­ ferent years. The relation between the maximum Zugunruhe and the time of greatest migration therefore, seems yet to be definitely established. The onset of Zugunruhe may be correlated with time of take-off. That the onset of restlessness may lead to flight is maintain­ ed by Ball who states: ’’Restlessness may be due to lowered thresholds to stimulation by external environmental changes other than light. Disturbances such as steep rise or fall in temperature, strong wind, and heavy rain, or the more incidental ones like the movements of an observer may arouse a bird into flight.” (Ball, 1952; p. 61). Assume a bird were to make a migratory flight, and the start of this flight were to occur at the same time as the start of Zugunruhe in caged birds. The bird mak­ ing a sustained flight may become fatigued comparatively rapidly and end its flight before the peak of Zugunruhe is reached by caged birds.

9"Analysis of observations for the past two fall migra- tion seasons has disclosed a marked tendency for the highest computed migratory flights to occur around the hour when the moon is highest in the sky, regardless of the time of night when the moon reaches this position. This may indicate that the mathematical procedures in use are over-correcting for the reduction in size of the cone of observation, or it may mean that the posi­ tion of the moon actually influences migration,” (Audubon Field Notes 8 (3), June 1954: p. 292- Atten- tion to Moon Watchers). ______-152-

Thus the peak of movement in a cage may not coincide with the peak of activity of a bird engaged in con­ tinuous flight. The restricted movements possible to a caged bird may be less fatiguing and the restlessness may continue for a long period of time. Actual mi­ gration would be in progress for only a part of the time that Zugunruhe is evidenced which implies that mi­ gration would occur in a series of short flights. On this point, practically no data were available. Banding data, wherein the bird is banded while in migration and recovered the same season, yield information only on the possible average length of daily flights. Lincoln (1950) records that the average speed of all species traveling up the Mississippi Valley is 23 miles a day. That birds evidently do successf ully make long flights is shown by band records of a lesser yellowlegs which indicated an average flight of 316 miles a day (Lincoln, op. cit.). This species, like most shorebirds, is a strong flyer; records for pass­ erines indicate much shorter average flights. A fur­ ther indication that short flights, and hence a short period of flight activity, may be common is submitted by Williamson (1952). He calculated that weight losses of 20 per cent or more are not uncommon in North Sea -153- crossings by passerines. Long flights would lead to fatigue or to a lowering of the energy reserves of the bird. Wolfson (1954) hypothesized that, on the bases of depletion and replen­ ishment of fat reserves, white-throated sparrows would be able to make single migratory flights of approximately 270 to 360 miles. This is based on a use of 6 to 8 grams of stored fat during a night flight of 12 hours. The birds would then arrive in an area with little or no fat. WoIfson states, "The birds which arrive in Evanston after a long flight during the pre­ vious night are low in weight and show little or no fat.11 but he also notes, "It is evident from our data that only a small proportion of the birds which arrive in Evanston have reached the minimum weight." (Wolfson, op. cit., p. 429). From the latter it may be inferred that a majority of birds do not always make the longest possible flight. The premise is thereby strengthened that the length of Zugunruhe may exceed the period of actual flight. Since Zugunruhe was not in the ducks or the shore- birds, the main concern here is with the evening peaks of activity, rather than with nocturnal activity. As -154- will be apparent, however, some of the above comments with respect to nocturnal activity are pertinent to the discussion of evening activity. In test II with the mallard drakes, evening activ­ ity appeared without any apparent change in the environ­ ment in the test chamber (See pages 123-124 and figures 14, 15,- 16). In some of the experiments reported by Palmgren (1949) and in those by Farner (1954) the birds were in outdoor cages, and evening peaks of activity could be correlated with the onset of twilight. The experiments conducted by Eyster (1954) made use of a number of test situations and with the exception of vari­ able temperature units, the birds were maintained under constant temperatures and light intensities. Eyster reports an evening peak of activity in white-throats (usually) and in slate-colored juncos (always), and a morning peak of activity in all species he studied. These peaks were noted when there was no change in light Intensity or temperature at either the beginning or at the end of the photoperiod. Eyster believes the daily rhythms are inherited and capable of only limited variation by external factors. In order to examine this viewpoint, and attempt to dis­ cover the causes of daily rhythms in ducks and shore- -155-

birds, consideration should be given to those factors which result in a variation of such rhythms* As some relation may exist between the peaks of activity during the photoperiod and the appearance of Zugunruhe, fac­ tors controlling the latter should be considered. Variations in food supply seem to influence Zugunruhe. Wagner (1937) found that birds fed sparingly were considerably more restless at night than well fed ones. By manipulating food supply he was able to re­ lease or suppress Zugunruhe in the European blackbird. With the red thrush, unrest could be reduced but not completely suppressed by food manipulation. During the non-migratory season a reduction in food supply did not induce Zugunruhe. Eyster (1954) noted that when food supply was low the white-crowned sparrow, white-throated sparrow, junco, and English sparrow exhibited an in­ crease in diurnal activity, but no increase was observed in the nocturnal activity. Attention should be called to a recent investigation on the ’'spontaneous" activity of hungry rats by Sheffield and Campbell (1954). They note that: "(a) Left to themselves, caged hungry rats appear to sleep much of the time and do not move about restlessly, (b) Very hungry rats have a lowered threshold for startle to a sudden stimulus, and when awake they are more active than satiated rats only if there -156-

is a variation in the external stimulation. (c) Hungry rats become maximally active when exposed to external stimulation which has regularly preceded feeding in the past experience of the animal." (Sheffield and Cambell, 1954; p. 97). The above, particularly item (c), may have a bear­ ing on the appearance of evening activity in the mallards of Test II. The investigator when entering the room con­ taining the chamber could not avoid making noise, nor could he avoid a temporary increase of light in the room, as its door led to the outside. This would in­ directly and momentarily light up the observation win­ dow. The investigator would then proceed to enter the chamber and feed and water the birds. After the birds fed, drank, preened, and stretched their wings they be­ came quiet. The rapid movement about the chamber, and the flight characteristic of the evening period was not seen. Once again, in the evening as the investigator entered the room prior to making observations, the same sounds, and flash of light occurred that preceded the midday feeding period. This created a situation some­ what akin to (c) above. The mallards were maintained in a hungry state (note page 1Q.G), and thus the even­ ing activity of these birds may be due to the present­ ation of cues previously associated with feeding. -157-

The importance of describing when and how feeding takes place with test animals is emphasized by Nalbandov, C1953) who believes that the time of feeding may be a more important factor that hitherto suspected. Temperature has been noted to modify both the appear­ ance and intensity of Zugunruhe, (Merkel, 1937). Wagner (1937) found that with song thrushes low temperature increased activity. In the mallards of the present study, there was no change in activity that could definitely be attributed to temperature. Temperature may be important through its effects on thyroid activity; thyroxine secretion is at its highest during seasons of low temperature, and low­ est in tvarra temperatures (Sturkie, 1954). The absolute light intensity or the time and se­ quence of photoperiods has profound effects on both Zugunruhe and diurnal rhythms. Wagner (1937) found that 0.273 foot-candles was the optimum light intensity for the initiation of Zugunruhe in the English robin. Palmgren (1936) noted that by turning strong lights on he could suppress or eliminate Zununruhe in certain species. Wagner (op. cit.) noted that continuous light would entirely suppress Zugunruhe in the thorngrass warbler. In complete darkness, Zugunruhe was entirely -158- absent (Wagner, op. cit„). Eyster (1954), however, found that nocturnal activity occurred in absolute dark­ ness. In continuous light the activity of juncos and English sparrows was fairly evenly distributed over the 24-hour day, whereas that of the white-throat was largely concentrated in a 14-hour period (Eyster, 1954). Of considerable importance to this duscussion are the ex­ periments by Eyster (1954) in which the 24 hour day was divided into two photoperiods. The first photoperiod was 6 hours long, the second was gradually increased from one hour to six hours so as to equal the length of the first photoperiod. Six hours of darkness intervened between the photoperiods. Both white-throated and white- crowned sparrows developed a double daily rhythm re­ lated to the two daily periods of light and dark. When the photoperiod was changed from two 6 hour periods to one 14 hour period per 24 hours, the birds immediately responded. Eyster (op. cit.) concludes that the daily rhythm was fixed, but could be changed by modifying the light schedule. In the present study, light was effect­ ive in increasing and changing the pattern of activity in mallards. As will be mentioned shortly, light seems to be im­ portant also in regulating the seasonal appearance of -159-

Zugunruhe. Previous training may have some effect on the pat­ tern of daily rhythm. Two birds after expieriencing two short photoperiods a day, retained a double peak of act­ ivity corresponding to these short photoperiods when re- 10 turned to the usual day-night cycle (Eyster, 1954). Causes of Diurnal Rhythms The daily cycle of activity seems to be correlated with migration, and since this cycle makes it appear­ ance in ducks and shorebirds, it is necessary to con­ sider more closely what may cause diurnal rhythms. Correlations which exist between fly-offs or even­ ing flights and various changing environmental factors have been discussed. The possibility exists that the daily rhythms are merely responses to changing stimuli situations of the environment. That light intensity or' temperature, or sequence and occurrence of photoperiods, can change the rate and appearance of activity seems to support this argument. In this manner the peak of act­ ivity appearing in caged birds soon after the commence­ ment of the photoperiod can be attributed to a response

10. This may not be due necessarily to training, for one of the birds had shown a double peak of activity be- fore being placed on the double light periods.______-160-

to increased light, and the following decline in activ­ ity to a condition of fatigue. However, the appearance of an evening peak under constant conditions of light and temperature, and the appearance of a nocturnal peak under absolute darkness, would not seem to support the hypothesis. A possible explanation of an environmental cause for the evening peak of activity has been advanced on page 156; however, this explanation depends on the birds being disturbed just prior to the end of the photoperiod,

* and evidently this was not the case in the majority of experiments described in the literature. Faced with this problem of daily cyclic activity with stable external en­ vironments, it seems necessary to propose the development of internal cyclic changes. In one form or another, the following theories of internal cyclic changes have ap­ peared in the literature: 1. Spontaneous cyclic activity of the nervous system directly stimulating behavior. 2. Spontaneous cyclic hormonal activity directly stimulating behavior. 3. Spontaneous cyclic hormonal or neural changes

resulting in changes of threshold levels to en­ vironmental stimuli. -161-

4. Cyclic hormonal activity induced by the ex­ ternal environment, with direct stimulation of behavior by the hormones. 5. Cyclic physiological changes, usually thought of as hormonal, induced by environmental changes which result in changing thresholds of response to external stimuli. The first four hypotheses are included to some degree in the following explanation of daily rhythms by Palmgren (1949; p. 567, and 575): ”1 have put forward the theory that the complex waves of diurnal rhythm represent the sum of superposed rhythms of various length, much as a sound is built up by superposed pure tones, and can be re­ solved by Fourier analysis, v. Holst has analysed the rhythmical movements of fins in fishes and found them to be governed by automatic nervous centers, working with different frequencies and able to add their influence on the muscles as a simple superposition. ... It seems a reasonable hypothesis that all or most of the postulated nervous systems react uniformly. This would imply that a short time before their being in a simul­ taneous state of decreasing activity, caused by the decreasing light and re­ sulting in sleep, they must be at a high level of stimulation. This immediately explains the almost general occurrence of the typical evening peak of activity, and mutatis mutandis also of the morning peak. The middle o£ the day is a natural consequence of the centres getting out of step, and also the occurrence of minor waves.” -162-

This theory presents a curious mixture of spontaneous (automatic) rhythms and environmental stimuli as causal factors. Spontaneity of the central nervous system is a strong feature of the Lorenz-Tinbergen school. Tinbergen (1952; p. 101) states: "The internal causal factors controlling, qualitatively and quantitatively, the motivation of the animal may be of three kinds: hormones, internal sensory stimuli, and, perhaps, intrinsic or automatic nervous impulses generated by the central nervous system itself.1' However, Tinbergen (op. cit.) also cites the importance of external stimuli in evoking the overt response# The existence of spontaneity in the central nervous system is not accepted by all psychologists. Leherman (1953; p. 350) notes: "As suggested by Gray and Lissman, rhymicity of behavior is much more parsimoniously explained in terms of periodic shifts in balance be­ tween central and peripheral pro­ cesses or interactions between different central processes, than in terms of the production of peri­ odic impulses by a single •Center* which, in Lorenz’s treatment has the character of a ’thing in itself’." A review of the literature regarding central nervous activity did not reveal any evidence, that could be accepted without reasonable doubt, which supported a theory of spontaneous central nervous activity, nor was -163-

there any evidence for hormonal activity without ante­ cedent cause. In the latter case, the literature is re­ plete with references to situations where environmental changes result in changing activity of endocrine glands. Hypotheses one through three (see page 160) may thus be rejected and attention focused on numbers four and five. Assume that the onset of a photoperiod stimulates some physiological change. This physiological change then stimulates behavior which appears in cyclic form due to the rhythm of the physiological change. Eyster, (1954) for fall migration. Farner suggests that in- » ternal stimuli (plus a certain metabolic state) may ini­ tiate migration of late spring or early fall migrants. Periodic internal stimuli could bring about the peaks of activity that occur in the evening and at night. How­ ever, if only internal stimuli were responsible for the initiation of migration, birds would take off in all kinds of weather and at all times of day as the in­ ternal factor became stimulatory. Present informa­ tion does not indicate that physiological changes alone will stimulate increased activity of an animal. Daily cycles in birds are known for pituitary activity,

thyroid activity, body temperature, erythrocyte counts, -164- spermatogenesis, basal metabolism, gastro-intestinal tract (depending on feeding cycles), and blood sugar. All of these cycles are interdependent and can be in­ fluenced to see how these cycles can directly initi­ ate daily activity. For example, Noble and Zithin (1952) mention that male chicks injected with test­ osterone proprionate attempted copulation. If the hormone were the stimulus, we might expect continued attempts at copulation, excepting periods of fatigue, and these attempts should occur at anytime. Actually the copulation attempts were reported only after a per­ iod of display and treading had occurred. Copulation was usually directed toward other birds but also the investigator*s hand would elicite agressive display and copulation attempts from the chicks. In other words, the injection of testosterone did not bring about activity per se, but evidently resulted in changes in the chicks which rendered them responsive to certain situations* Reference should be made again to the quotation from Sheffield and Campbell on page 135. Their work showed that hunger in rats does not result in increased act­ ivity, but that if the animals were hungry, they were more susceptiable to changes in the external environment. -165-

A review of avian internal cycles (Nalbandov, 1953; Sturkie, 1954) indicate that the peaks of none of these cycles in light of the present data, coincide with the peaks of activity noted in caged birds. There may be cycles yet to be discovered, but in the absence of sup­ porting data, consideration must be limited to those cycles already listed. The thyroid may be involved since thyroxine secretion rate is influenced by tem­ perature and amount of light. Measurements of thyroid activity of birds kept under static conditions apparent­ ly has not yet been done. Cycles Based on Digestive Tract Rhythmicity In the cycles of the digestive tract, fluctuations may occur which are comparable in time of occurence to the observed activity periods of the bird. This theory will be referred to as the G-T tract theory. Assume that a bird is maintained under stable con­ ditions on a 12-hour photoperiod. The bird does not feed at night (Eyster, 1954, found this to be the case with his birds). As the light goes on in the morning the bird is active and feeds for a while. This feeding in­ volves some movement. The early morning period of movement is followed by a decrease in activity. One would expect activity to -166- decrease after satiation of hunger, for there is little inducement for activity in a controlled environment, save for that initiated by the presence of other test animals in the same area* As evening approaches and hunger increases, the bird's threshold lowers and the bird becomes increasingly receptive to the existing environment. Subsequently activity increases, and the bird feeds. This continues until fatigued or until the onset of darkness. As hunger again increases during the night the bird becomes restless due to a lowered thres­ hold to environmental conditions (which in the case of absolute darkness may be temperature); this lowered threshold brought on by increasing hunger results in the response of the bird, leading to activity. At the onset of a new photoperiod the birds activity increases as it feeds, and the cycle is started again. This results in a three peak cycle; one peak is at night, and two occur during the photoperiod, at morning and evening. There are six general objections to this picture of events. 1. Zugdisposition is associated with increased fat reservers in some species. 2. Zugunruhe in passerines is present only in the migratory season. 3. The cycle appears in birds kept under con- -167-

ditions wherein food is always available. 4. Birds, in nature, may be able to feed at night. 5. Birds subjected to continuous light do not ex­ hibit a three peaked cycle. 6. The diurnal cycle of activity appears in a 6- hour photoperiod as well as in a 12- or 14-hour photoperiod. These are not necessarily contradictory to a cycle based on the G-I tract, as is shown by the following comments: 1. Comparing the non-migratory and migratory seasons, there appears to be a difference in physiology of the bird. In a number of migratory species there is an in­ crease in fat deposition, but th is does not happen in all migratory species. When this increase in fat does appear in the migratory species, it begins to develop just prior to the onset of the migratory period, and the bird is then considered to be in Zugdisposition. Zugdisposition is considered indicative of the changed physiology of the migratory bird. Non-migrants for the most part do not have a similar seasonal deposition of fat* Wolfson (1954: p. 372) says of Zugdisposition: "The precise nature of this change has not been studied, but one important mani­ festation of it would be an increase in appetite. With an increase in food intake beyond the normal energy needs the potenti­ -168-

ality exists for storage of this surplus food as fat. If food intake is restricted to only the amount required for basic needs, I do not believe the fat response could occur, despite the requisite physiological change.” Eyster (1954) noted that of two male white-throated spar­ rows maintained under identical conditions, only the one having a heavy fat deposit showed any marked nocturnal activity. It is possible to hypothesize that corre­ lated with the migratory season is an increased food in­ take brought about by changes in metabolism. Metabolic changes would be a reflection of increased thyroid and pituitary activity induced by changing seasonal photo­ periods. Having higher rate of metabolism would prob­ ably result in more rapid emptying of the digestive tract, thus inducing more frequent hunger stimuli which in turn would facilitate response to environmental stimuli. 2. The difference in metabolism between non-migratory and migratory seasons, resulting in different rates of onset and degree of hunger, may be effective in creating different patterns of activity in those seasons. Wagner (1937), however, noted that during the non-migra­ tory season a reduction in food supply did not bring on migratory restlessness. These experiments should be re­ peated, with varying degrees of food deprivation and with -169-

restrictions made on the time at which birds are per­ mitted to feed. It may be that in the non-migratory season an evening feeding period may suffice through a summer night, even though the amount of food is limited. Thresholds of response would not be lowered to a degree where the low light intensity or the night time tempera­ ture becomes stimulatory. This is highly theoretical, but the validity of the hypotheses can be subjected to tests and it would be profitable to do so. One such test, roughly, would be to maintain two groups of birds during a period of food deprivation. One group would be in absolute darkness, the other in light* If the act­ ivity of the birds in the light started sooner and reached higher peaks than of those maintained in the dark, some evidence for the foregoing explanation of activity would be obtained, i. e., the degree of response which is facilitated by hunger, to a non-fluctuating en­ vironment, depends on the relative energy level of the environment. 3. Where food is always available to captive birds the record of movements off and on a perch may represent the peaks of feeding activity. In Eyster*s (1954) experi­ ments a cage was used in which movements of the bird any­ where within the cage were recorded, including the act- -170- ivity of the bird about the feeder. These records were, to some extent, a measure of the peaks of feeding time during the day. This would support the G-I tract theory, for the feeding cycles of the birds would cor­ relate with hunger stimuli induced by the G-I tract. The same would be true for Farner's (1954) recent work. However, if the birds did not feed at night, then noc­ turnal activity may not represent feeding movements. 4. When birds are maintained under absolute darkness, no feeding at night would be expected. But in nature no night is absolutely dark, though light intensity is very low when heavy clouds cover the sky. Birds should thus be able to feed as nocturnal hunger increases, and, consequently, restlessness would be supressed. Obviously, some birds do not feed at low light intensities (witness the night roosts of starlings, pigeons, English sparrows, herons, and some ducks and shorebirds). Migratory birds may become active at night without feeding, though if hunger is facilitating the activity this would not seem likely. Evidently it may be possible, for Siebert (1949; p. 152) believes that migration south in the fall may be induced because during the shorter photoperiods the birds are not able to obtain sufficient food to maintain an energy balance over the 24-hour day (especially as the -171- days get colder). In other words, the birds may be hungry and yet not feed during the night. 5. Birds subjected to continuous light have been ob­ served to be active throughout the day, or to exhibit a gradual rise then a fall in activity. Actually, as far as the test animal is concerned, there is no reason to consider activity as on a 24-hour cycle since there are no external clues to the beginning or end of a period of time for the experimental subject. If the investigator makes daily or semi-daily feedings of the animal, this may induce some rhymicity into the continuous photo­ period. As Sheffield and Campbell C1954) noted, act­ ivity in hungry animals may occur when environmental cues normally preceding feeding appear. Thus the way is clear for the establishment of a rhythmic activity of animals, though they are subjected to a continuous photo­ period. In continuous photoperiods no marked peak com­ parable to a nocturnal peak was known to occur (Eyster, 1954), and this would be expected because the birds are able to feed at any time. No change in light intensity occurs, so that there is no stimulus directing morning activity and feeding. 6. Eyster (1954) notes that birds kept on a 12-hour cycle of day and night, instead of the usual 24-hour -172- cycle, exhibited two nocturnal peaks of activity when returned to the usual 24-hour day, A previously cited comment by Eyster (see page 158) indicates that the diurnal rhythm was readily adaptable to the photoperiod length. Yet, if the double nocturnal peak is a result of previous experience, and we accept the idea that the basic rhythm is related to hunger, then the G-I tract cycle is subject to rapid fluctuations which can be es­ tablished by conditioning. If this appears to be a major obstacle to the acceptance of the G-I tract theory, it is also one for the acceptance of a theory involving cyclic hormonal secretion as a cause of daily activity rhythms. Light, Temperature, and Hormonal Cycles Photoperiod length, sequence of photoperiods, and temperature seem to be fundamental in inducing, either directly or indirectly, daily cyclic hormonal changes in birds. In test I and II light intensity was constant ex­ cept for changes during the evening test periods, and temperature was either varied (testl) or was kept con­ stant (test II). The length of the photoperiod was the same in all tests. Where constant light conditions prevailed and no -173-

relation is noted between temperature and activity, (this was true in the test with mallards), it is dif­ ficult to see how cycles of activity could be regulated by hormones. Daily rhythmicity induced by variations in food consumption and feeding schedules seems more likely. In test I and II with mallard drakes, there was a daily variation in amount of activity in the evening. This daily variation may be related to food intake. The experimental design was such that a significant measure (with respect to evening activity) of food consumption was not possible. The change from light to dark or vice-versa may be a stimulus which could influence rate of hormonal secre­ tions. A change in hormonal balance resulting therefrom may ultimately bring about activity in one way or an­ other. If, for example, the change from light to dark is stimulatory, this might account in part for the appear­ ance of nocturnal activity. The resting period noted be­ fore the onset of nocturnal activity (Eyster, 1951) may be the time required for the hormonal change to become effective. If one proposes a hormonal cycle as basic to daily activity, one should be aware of a comment by Nalbandov: -174-

"Causes for hormonal rhythms are not clear. Purely in the realm of specu­ lation is the assumption that basically all diurnal rhythms are governed by the change in light intensity... An attempt to introduce some order into the high and low points of diurnal physiological activity enumerated above falls, and no common pattern of activity is notice­ able. u (Nalbandov, op. cit., p. 98, 99). The main points in favor of a G-I tract cycle as basic to diurnal rhythms of migratory birds, aside from the difficulty of attributing these rhythms to hormonal cycles, are: 1. Zugunruhe in some species can be suppressed by manipulating food supply. 2. Zugunruhe in some species can be intensified by low amounts of food. 3. Diurnal activity can be increased by decreasing food supply. 4. On continuous photoperiods when birds can feed anytime, no peak of activity appears that is similar to the unrest developing in darkness (when birds do not feed). 5. Hunger results in an increased response to environmental changes. The weakest part of the hypothesis is the assumption that in a non-fluctuating environment a changing threshold of response may result in cyclic appearance of activity. -175-

This point is subject to experimental confirmation. Whatever is basic to daily activity patterns, the actual expression of behavior may be a complex of un­ learned and learned responses, and experimentation in this field should be conducted in awareness of this. Daily rhythms can be very much influenced by environ­ mental changes, and the degree of innateness of these rhythms remains yet to be demonstrated. Seasonal Cycles of Activity Practically all of the factors that have been dis­ cussed with respect to daily rhythms have been con­ sidered also in the literature dealing with seasonal activity, i.e. , the migratory versus the non-migra- tory seasons. A summary of the annual cycles has been given by Farner (1950). Since the main concern in the present study was with daily cycle, there is no reason to go into a detailed discussion of these seasonal cycles. Briefly, it is the present conception that seasonal physiological changes in metabolism occur. In some species fat is accumulated. The seasonal changes are probably related to cyclic function of the pituitary in­ duced by periodic external factors. Photoperiodis® has been considered a significant external causal variable. - 176-

Wolf son (1954) has been able by manipulation of photo­ periods to induce periods of fat deposition and gonadal activity in white-throated sparrows several times a year. The seasonal physiological change may be related also to thyroid activity, adrenal activity, metabolic rates, or gonadal activity. Once the seasonal change occurs and the bird is in Zugdisposition, migratory stimuli may be effective. Some authors suggest that no external stimuli to migrate are necessary (Farner, 1950); however, the opinion formed in the present study is that external stimuli are necessary. As long as an animal is alive it is responding to external stimuli, and it never ceases to do so while it lives. Any behavior or be­ havior pattern is a dynamic working of changes in the machinery of the organism, changes in its reception of the external and internal environment, and changes in that environment. In the final analysis it seems that an overt action by an organism would occur only when a receptor is stimulated. Suggested Hypotheses for the Initiation of Migration In summarizing the foregoing discussion, and in mix­ ing hypothesis and fact, the following theory may be de- -177- veloped: The daily peaks of activity of black ducks, mal­ lards, and of certain shorebirds suggest that a daily cycle based on the G-I tract results in changes in threshold to environmental stimuli. Morning and even­ ing changes in light intensity provide a stimulus sit­ uation to which these birds respond. The result may be a feeding flight, a roosting flight, or a migratory flight. The same general hypothesis may be true for passerines. The G-I tract cycle may vary with environ­ mental changes, and the effect it has on changing thres­ hold may depend on other facilitation factors (increased social activity for example), and be modified" by fatigue. Imposed on all of this may be learned behavior. These daily cycles in turn are related to the longer seasonal physiological changes. The theory as proposed above does not answer all of the questions. For example, the ducks and shorebirds that have moved into 0* Shaughnessy have completed a mi- gatory flight of some sort. Why do some remain for two weeks and others pass through immediately? The stimulus that will induce departure of ducks or shorebirds does not seem to be constant for every individual, unless the ac­ tual stimulus situation was not discovered in the present -178- study. In other words, the stimuli are not part of movements of air masses, or degrees of overcast, or the like. The stimuli may involve factors of humidity, radiation, barometric pressure, and so forth. More likely, however, is the possibility that the dif­ ference in responses lies in the receptiveness of the individual bird, rather than in minute environmental changes. Mallards coming to the reservoir after a long flight may reouire a period of feeding and rest­ ing before proceeding. Wolfson (1954) believes that white-throated sparrows arriving in Evanston, Illinois, with little or no fat, remain in the area until fat is replenished. Is nocturnal restlessness associated with birds that have utilized their fat deposits? Again re­ ference may be made to Eyster*s (1954) observation that of two white-throated sparrows maintained under similar conditions only the one with a fat deposit showed any Zugunruhe, the other,w ithout fat deposits, remained quiet at night. Perhaps the pectoral sandpipers that were known to stay for two or more days at the reservoir were replenishing energy reserves. For a time their evening flight may have resulted in flights to roost, or feeding flights. But why would replenishment of energy reserves then lead a bird to migrate? Why would - 179-

no t Zugunruhe result in shorebirds and ducks feeding at night, instead of migrating, if activity is based on a hunger cycle? Furthermore, some ducks and shorebirds left the area when food was still available. Social factors do not explain these questions entirely, though they are certainly involved in facilitating and eliciting responses, for not all individuals of the same species leave an area at the same time. Though in this paper some idea may have been gained of what will stimulate activity, and flight in certain species, and under what conditions migration may have occurred, the preceding questions and comments demon­ strate that more problems have been raised than answered. Why a duck or shorebird migrates at a particular instant, why it makes a sustained flight instead of feeding or roosting, and what guides it on its way, all of these and other problems must be studied further before description of migration be permitted to fall back on the meaningless use of "migratory urge" as a panacea. Specific studies are needed on the relation of feed­ ing time, and the quantity and quality of food on activ­ ity of birds. Measurements are needed of the activity cycle of non-passerines other than chickens. The effect of previous training should be studied. The relation of food deprivation to thresholds of response must be ex­ plored, as well as the relations between fatigue and thresholds of response. An understanding should be gained of the effective variables producing responses in different species of birds. Above all, the ex­ perimental work should be done xvith both biological and statistical reliability. The emphasis could be placed on physiological and behavioral investigations under controlled conditions, though field work should not cease, for it is only through this latter medium that the laboratory work can be directed and related. Ul­ timately, an understanding or the field situation is what is desired. No matter how fine and complete the coordination between field and laboratory work, probably no one answer to bird migration will be found. This statement is made because the wide variation in migration phenomena from species to species, individual to in­ dividual, and from one time to another, have led the investigator to believe: 1. The origin of bird migration may be as old as the family tree of birds. Moreau (1950; p. 248) remarks: "... it seems that on this perspective -181-

it is right to regard the present im­ mense phenomena of Palearctic and Nearctic migration as representing, on the geological time scale, only a tem­ porary stage of a process and a system as old as well-developed flight.5' 2. With such ancient origin, it is not suprising that migration may have had several origins. Farner (1950; p. 104) notes: "... it appears not unlikely that mi­ gratory behavior may have envolved several or many times in the course of the evolutionary history of modern birds and that, in studying migra­ tion, we may actually be confronted with many subtle cases of covergent evolution.*' Kalela (1954) believes that any migratory activity lead­ ing to survival would be selected for, and thus one could expect many differences in processes and stimula­ tion of migration. 3. Bird migration is probably still evolving. As with any biological process there is no point structure and function become static. Not all birds are successful migrants, and perhaps not all species are successful. There is no reason to assume that bird migration has been completely developed, and that selection is at an end. Nor should it be assumed that all the patterns have appeared on which selection will -182-

act. Natural selection itself is not a fixed tool which acts as a knife cutting through cheese; what is a selecting factor changes with time and varies with the variations of the organism. Faced with a process that may have begun in the Jurassic, a process that is still developing, and one which is not always successful in maintaining the life of the individual, and being able to view this in a small segment of time, it is no wonder that it would be difficult to find a single answer to bird migration. Bennett (1952) noted that an error may creep into samples due to purely chance differences in numbers of birds present in an area. These birds are not there due to chance; they are there because there is some inter­ action between them and the dynamics of their environ­ ment. To understand any part of bird migration we must ultimately be able to understand the reasons for these "chance" occurences. Therefore, despite the multipli­ city of phenomena in bird migration, this investigation of some aspects of the role of weather in bird migra­ tion has largely been concerned with the stimulus- relationship of a few environmental variables and the behavior of only a few species. -183-

SUMMARY Observations were made on selected species of black ducks and shorebirds during spring, winter, and fall of 1952, 1953, and 1954 at O ’Shaughnessy Reservoir, Delaware County, Ohio. Additional observations were made at Buckeye Lake, Fairfield County, Ohio, Magee Marsh, Ottawa County, Ohio, and Scioto Lakes, Franklin Cotmty, Ohio. Records were kept of the number of ducks and shore­ birds observed, and their behavior at different times of the day. Weather elements were measured with particular reference to wind velocity, light intensity, air tem­ perature, cloud cover, and frontal activity. Records were obtained of the changes in water levels and water area at O ’Shaughnessy Reservoir. An attempt was made to determine if correlations existed between the en­ vironmental factors recorded and the behavior or changes in numbers of the birds observed. Laboratory tests were conducted on five mallard drakes to determine the influence of light intensity on evening activity and flight. The numerical status of mallard and black ducks varied from day to day during the migratory season. The variation in numbers of mallards was due in part to the -184-

artificial feeding maintained by the Columbus Zoo. No consistent relationship was found between de­ creases in numbers of black ducks and movements of fronts, temperature, wind velocity, or degree of cloud cover. Increases in numbers of black ducks in the fall might be associated with cold fronts passing over the state, or with the occurrence of colder weather'to the north. The number of black ducks present in December of each year appeared to be related to the available water area. Diurnal behavior of black ducks and mallards was similar, though these species remained more or less in separate flocks. From 0800 hours to 1600 hours mallards and black ducks intermingled periods of sleeping, rest­ ing, feeding, and courting. Occasionally birds swam or flew to various areas on the reservoir. The number of ducks active and swimming about was more noticeable on overcast or near overcast days than on clear or partly cloudy days. A majority of black ducks and mallards in flocks resting on the water oriented into winds having speeds above 250 feet per minute. Birds resting on shore were less responsive to the wind, and on several occasions their behavior appeared to be independent of wind speed. -185-

Flocking behavior appeared to be influenced by the number of birds in a flock, but was independent of wind velocity, temperature, or cloud cover. Birds in flocks on shore almost invariably were within one body length of each other. A feature of the diurnal behavior of black ducks and mallards was the evening and morning flights. Most of these flights were made to nearby feeding areas, though some migration might have occurred at this time. Usually preceding evening flights the birds* activity on the water increased, and flock density increased. Mallards preceded black ducks in the initiation of evening flight. The time at which evening flight was made, and the duration of take-off seemed to be a func­ tion of light intensity, degree of overcast, and the number of ducks present. There was no correlation between temperature or wind velocity and the initiation time of evening flights. The direction of evening flights did not correlate with the weather factors studied. Shifts of direction of flights may have been due to hunting pressure at the feeding grounds. The laboratory tests confirmed the hypothesis that light was a significant variable in both preflight act­ -186-

ivity and evening flight of mallards. Changes in light intensity were not necessary to initiate evening act­ ivity and flight, but decreasing light intensity re­ sulted in a greater amount of activity. Considerable day to day variation was noted in the amount of activity under laboratory conditions. When light intensity was reduced, however, the activity de­ veloped was inversely proportional to light intensity. Individuals and species of Aythyiae were more nu­ merous at the study area in the spring than in the fall, indicating a seasonal difference in flight paths or length of stopover periods. Redheads, lesser scaups, and ring-necked ducks spent most of the day either resting in compact flocks on the water, or feeding in various areas of the reservoir. Based on data from feeding groups of ring-necked ducks, not all birds remained with the same group day after day. Scaup flocks resting on the water oriented into winds having speeds over 250 feet per minute. Usually all birds of a scaup flock responded alike to the wind, which was not the case in black ducks and mallard flocks. Diving ducks made evening and morning flights from feeding areas to roosting areas. The initiation of these flights could be correlated with light intensity. -187-

In general, shorebird numbers fluctuate with the amount of feeding area (mud flats) exposed during the migratory season* Increases and decreases of pectoral sandpipers seemed to be correlated with cold fronts. Correlations were less evident between weather variables and changes in numbers of semipalmated and least sandpipers and dunlins. Migrating shorebirds were known to remain in the area for as long as two weeks. The daily activity of most shorebirds v

With respect to field observations: 1. More information is needed on the relation of observed numbers to the actual progress of migration. 2. More data are needed on the factors influencing length of stopover and stopover range. 3. Sampling techniques must be developed with a view to the statistical reliability of the method and awareness of the influence of local factors on the sample. 4. Migration studies must consider more species separately, until data are available which supports the treatment of several species as one. 189

Table 1

NUMBER OF HOURS SPENT IN THE FIE ID

AT A GIVEN HOUR

TIME OF DAY- TOTAL NUMBER OF HOURS IN FIE ID

04 00-05 00 0.75

0500-0600 3 . 0 0

0600-0700 9.50

0700-0800 1 2 . 0 0

0800-0900 34.75

0900-1000 101.61

1 0 0 0 - 1 1 0 0 101.75

1 1 0 0 - 1 2 0 0 47.75

1200-1300 16.50

1300-1400 7.75

1400-1500 14.75

1500-1600 21.75

1600-1700 28.75

1700-1800 35.00

1800-1900 29.60

1900-2000 10.75

2 0 0 0 - 2 1 0 0 0.50 TOTAL 476.46 Table 2

CLOUD COVER AND WIND VELOCITY RECORDED AT 0 ’SHAUGHNESSY RESERVOIR

COMPARED WITH DATA FOR COLUMBUS, OHIO TAKEN FROM THE U. S. WEATHER

BUREAU MAPS, 1953.* d a t e TIME FIEID RECORDTIME WEATHER” BUREAU DATA

Nov* 18 1700 OISO Oot* 27 0930 % 0130 Nov, 2 0 0925 0130

Nov, 2 1 0900 0130 J • Nov* 2 2 1330 J* 0130 Nov* 23 1930 J• 0130 Nov* 24 1 0 0 0 f 0130 Dec* 6 1500 J® 0130 Deo . 7 0940 0130 Dec* S 0940 J 0130

♦See appendix for explanation of symbols* -191-

Table 3

EXAMPLES OF ERRORS CAUSED BY LUMPING SPECIES COUNTS

DATE NUMBER OF NUMBER OF NUMBER OF TOTAL (Sept. 1952) PECTORAL LEAST SEMIPALMATED FOR ALL SANDPIPERS SANDPIPERS SANDPIPERS THREE SIECIES

1 10 50 25 65

2 13 7 45 65

3 16 26 55 77

4 7 7 7 ?

5 10 16 15 41

6 15 9 22 46

7 15 1 25 41

8 8 4 8 30

9 8 2 35 45

10 3 10 39 52

11 13 9 27 49

12 12 9 21 42

15 14 10 9 33

14 16 9 10 35

15 19 6 10 35 -192-

Table 4

DISTRIBUTION OF MALLARDS ON O'SHAUGEKESSY RE SERVICE

OBSERVATION FALL-WINTER PERIOD WINTER-SPRING PERIOD AREA 1952 1955 1 953 F. 0.*— PER CENT F. 0.— PER CENT F. C , PER CENT i i I i

1 6738 ------37 5332 CD 1 2 2 1

2 2931 ------17 1177 ------« 1 1 462 ------is

3 1663 ---- 9 1460 ------is 521 ------14

4 3927 2070 ------19 1 0 0 ------3

5 2253 ------12 945 ------8 263 ------7

6 0 ------0 36 ------o 81 ------2

7 125 — ----- 1 7 ------1 401 ------11

8 372 ------2 30 ------0 587 ------16

ALL 18,009 1 0 0 11,057 1 0 0 3,636“ 1 0 0 OBSERVATIONS

* F. 0* - frequency of obsearmtion. -193-

Table 5

RANK OF OBSERVATION AREAS AT 0*SHAUOHNESSY ACCORDING TO RELATIVE SIZE,

LENGTH OF SHCRELINE, AND FREQUENCY OF OBSERVATION OF MALLARDS.

(FALL-WINTER FERIOD)

OBSERVATION4 Vkt&UENCV OV l&LATlVE Sl2E RELATIVE lENGTH AREA OBSERVATION AT 835’ LEVEL OF SHORELINE 1552 1953

1 1 1 4 3

2 3 3 3 2

3 2 2 1 S

4 5 4 2 7

5 4 5 5 6

6 6 7 8 5

7 8 6 7 4

8 7 8 6 1 Table 6

DISTRIBUTION OP BUCK DUCKS ON 0*SHAUGHNESSY RESERVOIR

tobsEftmioif .mcwiHrrarTHrjro ' W i n t e r -s w i n g m i ® AREA 1952 1953 1953 F. 0.*— PER CENT F. 0.— PER CENT p. o . --- PER CENT

1 2 3 1 --- 1 5 3 5 --- 5 116 ------4

2 3,198--- 13 550 — — 5 423 ----- 13

3 3,940 --- 16 956 --- g 811 ----- 26

4 11,251--- 46 5,827 —— ■ 55 278 ---- - 9

5 4,765 --- 20 2,513--- 24 671 -— 2 1

6 2 4 --- 0 1 9 2 --- 0 16 ------o o> 04 1 1 1 7 877 --- 4 1 785 -— -- 25

S 1 9 --- 0 0 --- 0 65 ----- 2

All 24,305 100 1 0 ,6 6 ? 1 0 0 3,165 1 0 0 OBSERVATIONS

*F, 0. I frequency of observation. -IBS-

Table 7

RANK OF OBSERVATION AREAS AT Q* SHAUGENESSY ACC CRD TNG TO RELATIVE SIZE,

LENGTH OF SHORELINE, AND FREQUENCY OF OBSERVATION OF BLACK DUCKS.

(FALL-WINTER HSRIOD)

OBSERVATION FREQUENCY OF RELATIVE SIZE RELATIVE LENGTH AREA OBSERVATION AT 835 * IEVEL OF SHORE LITE 1952 195S AT 847* IEVEL

1 6 5 4 3

2 4 4 3 2

3 3 3 2 7

4 1 1 1 3

5 2 2 5 6

6 7 6 7

7 5 7 6 1

S 8 8 8 5 Table 8

DECREASES* IN DAILY COUNTS OF BLACK DUCKS AT 0 ’SHAUGHNESSY RESERVOIR

AND ASSOCIATED WEATHER DATA

t)ATE d A i l t W c W StilttASY Ob " H r n m — 1952 COUNT DECREASE FIE ID WEA- SYSTEMS-7^ THER DATA /

Oot. 24 249 C old fr orrt on Oct. 19 - 20 Oot. 25 130 47

Oot. 28 2 0 2 Cold front on Oot. 27 - 28 Oot. 29 105 48

Nov. 3 284 Cold front on Nov. 2 - 3 Nov. 4 2 2 0 22

Nov. 14 376 Cold front on Nov. 9-10 Nov. 15 228 39

Nov. 19 294 Active front Nov. 19 - 20 Nov. 20 247 16

Nov. 29 864 29 C old f r ont on Nov. 26 Nov. 30 454 47 28

Deo. 1 690 30 Cold front on Nov* 26 Dec. 3 467 32 28 I * iDecreesee of 1§& or more. / Data collected from 0800 to 0900 hours. Temperature is in degrees Farenfeeit to compare with Weather Bureau data. From data furnished by U, S. Weather Bureau (see appendix far explanation of symbols). Table Sb

DECREASES* IN D A I U COUNTS OF BIACE DUCES AT O'SILAUGHNESSY RESERVOIR

AND ASSOCIATED HEATHER DATA

DATE Mils' FteR cH it SUMMARY OF FkoWTAL 1953 COUNT DECREASE FIELD WEA­ SYSTEMS THER DATA

N o t , 1 149 Cold front on Oot. 25 - 24 Nov, 2 97 35 56£ )

Nov. S 376 Cold front on Nov. 3 - 4 Nov. 9 297 2 1 4° - #

Nov. 13 375 42 @ C old fr onfc on Nov. 3 - 4 Nov, 15 250 33

Deo. 13 619 C old fr onfc on « Q . Dec. 12 - 13 Deo. 15 290 53 \ J 3 - 0

Dec. 15 290 Weak cold front Deo. 16 - 17 Deo. 17 69 76 8 O

* Decreases of 16$ or mere. -198-

Table 80

DECREASES* IN DAILY COUNTS OF BLACK DUCKS AT 0 »SHAUGHHESSY RESERVOIR

ARP ASSOCIATED WEATHER DATA

DATE DAILY PER CERT SUMMARY Ol’ M o l U 1954 COUNT DECREASE FIELD WE A- SYSTEMS ______THER DATA

Now. 15 281 C old fr ont on Nov. 14 - 15 Nov. 15 199 31

Nov. 19 391 5 7 # Cold front on Nov. 19 - 21 Nov. 21 318 19

Nov. 28 359 Cold front on Nov. 29 - 30 Nov. 29 291 19

Deo. 17 2749 31 Occluded front on Dec. Deo. 20 0 100 37 17 - 19

* Decreases of 15J& or more.

Data on numerical atatua of black ducks in 1954 furnished by Robert Winner. -199

Table 9

INCREASES IN DAILY COUNTS OF BLACK DUCKS ON O'SHAUGHNESSY RESERVOIR

AND ASSOCIATED WEATHER CHANGES*

DATE DAILY WEATHER COURT 1952

Dec. 2 467 Coldest weather recorded on Deo. 1-2. From Deo. 3-11 pronounced warm weather Dec. 4 1378 over state.

Deo. 6 1274

Dec. 6 1355

Deo. 16 1130 From Dec. 11 - 15, polar-Canadian air dominated state. On Deo* 16, skys clear. Deo. 18 1947 air mass •warmer . Mild period extended from the 16 - 25 of December 195S

Deo. 2 319 Fast moving oold front over state on Dec. 4. Dec. 5 535

Dec. 12 520 From the 14 - 16 of December, oloudy damp weather prevailed. On the 9th. an active Dec. 13 619 front passed through the state. From the 2-13, temperatures were above normal state wide. A cold front passed through from the 12 - 15 of December. 1954

Dec. 2 429 Coldest December since 1951, Dec. 1 - 8 had repeated invasions of polar air. Deo. 4 S59 Snow fell along Lake Brie and southward across the north counties of Ohio. Weak cold fronts aooampained Invasions of Dec. 4 S59 cold air. From Dec. 11 — 16, temperatures were higher. Light snow or rain was Deo. 5 1114 frequent. Table 9 cont.

INCREASES IN DAILT COUNTS OF BLACK DUCKS ON 0*SHAUGHNESSY RESERVOIR

AND ASSOCIATED WEATHER CHANGES*

DATE DAiUr COUNT WEATHER 1954

Dec . 6 1006

Dec . 7 1609

Dec. 7 1609

Dec* 8 1940

Dec. 8 1940

Dec. 9 2 1 0 0

Dec. 9 2 1 0 0

Dec. 11 2822

* Adapted from weather data furnished by U.S. Weather Bureau -201-

Table 10

EXAMPLES OF THE LOCATION OF BLACK DUCKS AMD MALLARDS

WHEN IN CONTIGUOUS FLOCKS

DATE TIME LOCATION OF MALLARDS XoCATION OF BLACKS 1952

Nov. 17 1025 On shore On water

Nov, 11 0930 Near shore On water

Nov. SO 1507 To NW of blacks Some in with mallards

Deo, 4 0900 Mostly in one group Not with mallards

Deo. 8 0930 Along shore West of mallards

Deo. 11 0900 Mostly on shore On water

Deo. 13 1 0 0 0 Most at shore On water

Deo. 16 0955 South of blaoks North of mallards

Deo. 18 0845 At west shore On water & east shore 1953 / Nov. 13 0925 . At share On water

Nov. 22 1345 At share On water

Deo. 2 1 0 1 0 South of blacks North of mallards

Deo. 5 1 0 0 0 On share On water

Deo. 6 1550 At share, on water With mallards

Deo. 8 0955 At & on share On water

Deo. 11 1050 On shore On water

Deo. 13 1140 On shore On water -202-

Table 10 oont.

EXAM PIES OF THE LOCATION OF B1ACK DUCKS AND i/A 1LARDS WHEN IN CONTIGUOUS FLOCKS

DATE..... f f m .... LOCATION OF MALLARDS.. . LOCXtION OF BLACKS 1954 Nov. 8 163-0 Near ahore On Water

Nov. 9 1638 Near share Near center of water

Nov. 12 1635 Near share On water

Nov. 15 1635 Near shcre Same shore; on water

Nov. 19 1701 Near share Same shore; on water

Nov. 22 1625 Near west shore On water A east share

Nov* 23 1615 On west shor e On water & east shore

Nov. 29 1S25 At or on shore On water

Deo. 2 1625 At car on shore On same shore; on water

Deo. 4 1635 At or on shore On same shore; on water

Dec. 7 1635 On share On same shore; on water -203-

Table 11

DEGREE OF CLOUD COVER IK FALL-WINTER OF 1952 AM) 1953 COMPARED TO

SIGNIFICANT MOVEMENT OF MALLARDS AMD BU C K DOCKS ON THE WATER

(SEE TEXT FOR EXPLANATION)

DEGREE CF PER CENT OF DAYS WITH THE DESIGNATED CLOUD COVER CLOUD COVER ON WHICH SIGNIFICANT MOVEMENT WAS NOTED, MALLARD BLACK DUCK

0 . 0 0 0 0

0 . 1 0 0 0

0 . 2 0 0 0

0.30 0 0

0.40 0 0

0.50 0 0

0.50 0 0

0.70 0 0

0.80 25 28

0.90 0 0

1 . 0 0 38 33 -204-

Table 12

WIND SPEED AM) ORIENTATION OF MALLARDS AMD BLACK DUCKS

RESTING ON THE WATER-/

WIND SPEED H3R CENT OF DUCKS FACING WIND IN FEET/MINUTE______AT TIME OF OBSERVATION

2070 ------100 1352 ------100 1200 ------90 - 100 1080 ------90 - 100 1030 ------60 1 0 0 0 80 - 1 0 0 975 ------100 970 ------100 900 - 100 860 ------55 820 1 0 0 740 . 9 5 . 1 0 0 725 ------100 720 60 - 100 7 1 0 ---- 100 700 ------67 680 67 - 90 640 ------100 580 ------100 550 ------100 5 3 4 ------100 530 ------100 500 ------90 - 100 470 ------75 460 ------x * 450 ------* 420 ------x - 100 370 - --- 60 - 100 360 ------X 350 ------.... ------50 - 60 340 ------100 320 ------x 286 ------x * 280 * 275 ------x 270 ------51 250 ------60 -205-

Table 12 oont,

WHIP SreED AND CRIBNTATION OF MALLARDS AND BLACK DUCKS RESTING ON THE WATER /

W ind "srsfeB per cent of d u c k s pAci3c“flND IN FEET/folNUTE______AT TIME OF OBSERVATION

2 0 0 ------x 160 ------x 1 1 0 ------x 1 0 0 ------x 7 6 ------X 1 ------x 0 ------x

x birds faoe no one particular direction,

* birds faoe in direction other than that of wind,

/ Each per cent: has been obtained from the observation of more than one flook. -206-

Table 13

WIND VELOCITY AND ORIENTATION OF MALLARDS AND BLACK DUCKS

RESTING ON SHORE*

WIND SPEED WIND ORIEWt ATION WD U C K S LOCATION IN FEET/klNUTE DIRECTION WITH RESPECT TO: OF BIRDS WIND WATER

2070 sw XX 0 west shore, 5

1275 NW XX X

1 0 0 0 S XX

980 NW XXX

980 NW 0 XX west shore, 2

740 ssw XXX

740 ssw X 0 west shore, 5

725 s XX 0 west shore, 5

710 w 0 XX west shore, 2

680 NW XX X

640 SW XX XX

640 NW XX X

580 WNW 0 X west shore, 2

580 WNW X XX

580 WNW X 0 west shore, 7

530 SSE X 0 west shore, 5

470 S X 0 west shore, 5; east shore, SO- of 3 Table 13 cont.

WIND VELOCITY AKD ORIENTATION OF MALLARD AID BLACK DUCKS RESTING

ON SHORE*

WIND SPEED' WIND ORIENTATION OF DUCKS LOCATION IN FEET/klNDTE DIRECTION WITH RESFECT TO j OF BIRDS WHO WATER

470 S X X

470 s X XX

470 SSE 0 X east shore, 5

420 SW XX X

420 m faoe no one direction

370 w XX XX

360 SSE 0 XX east shore, north of 2

360 SSE XX 0 east shore, south of 2

360 SSE 0 XX west shore, 2

280 SSW 0 XX

250 NNW X XX

100 SW XX 0 west share, Zaoj facing open field

under 100 N 0 XX

* Does not include ducks at zoo* See Table 14. xx Majority faoe directly into the wind or faoe the water, according to the column indicated, x Majority faoe within 45 0 of either wind direction or direction of water, according to the column indicated. 0 Majority face away from either wind direction or direction of water, according to tbs column indicated. -208-

Table 14

WIND VELOCITY AND ORIENTATION OF MALLARDS AND BLACK DUCES

RESTING ON EAST SHCRE AT ZOO FEEDING AREA

WIND SFEED WIND ORIENTATION OF DUCKS IN FEET/klNUTE DIRECTION WITH RESPECT TO: WIND WATER 2070 SW XX 0

1 0 0 0 S 0 0

980 NW 0 0

970 N 0 0

855 W 0 0

820 N XXX

740 SW X 0

700 SW XX 0

550 sw XX 0

530 sw 0 XX

500 SE XX 0

500 SW XX

460 NW 0 0

420 NW 0 0

370 w X XX

320 SE XX 0

286 SE XX 0

280 SSW 0 0

100 SW X X

Note* for explanation of symbols see Table 13. -209-

Tabla 15

FREQUENCY OF OBSERVATION OF BLACK DUCKS AMD MALLARDS RESTING ON SHORE

IN RELATION TO m i © DIRECTION

FREQUENCY OF DIRECTION OF WIND* OBSERVATION »Ci) SB(2) S(2) Sw(7) W(2 ^ RW(5)

East shore 0 416 277 1015 545 567

West share 17 260 1876 1370 451 328

* Numbers in parenthesis indicate the number of times the wind was recorded from the direction indicated. -210

Table 16

GREATEST AND MOST UNIFORM FlDCK DENSITIES RECORDED

IN OBSERVATIONS OF 135 FLOCKS OF MALLARD AND BLACK DOCKS

DATE Til® LA ' ' ACTITIIY^ OF''DUCKS AT TIME CP OBSERVATION A Oot. 2 0 , »53 s Movement preoedicg evening flight A tt ti tt it Nov, 23, *52 1713 s tt it tt n Nov, S, *52 1725 If ’- l

II n tt it Nov. 8 , *54 1630 1

II it it ii Nov. 8 , *54 1730 1

Nov. 1 2 , *54 1730 1 tt it it n

Nov. 23, *54 1645 1 n ti tt it

ii ii tt ti Dec. 6 , *54 1630 1

Nov. 23, *54 1715 1 it it it n

ii ii it Deo. 7, *54 1700 1 tt

tt M it Deo. IS, *54 1641 1 ti

it It it Deo. 14, *54 1637 1 it

Dec. 8 , *53 0955 1 Resting on water

Deo. 1 0 , *53 1007 1 Moving to eenter of water

Nov. 2 1 , *52 0945 i-2 Resting on water

Dec. 18, *52 0850 ir-2 ti ii n

Dec. 8 , *53 0955 lr-2 Feeding in shallow water -211-

Table 17

COMPARISON OF SIZE AM) DENSITY OF FLOCKS OF BLACKS AND MALLARDS RESTING ON THE WATER (FIGURES ON TABLE -ARE NUMBERS OF FLOCKS)

No. OF DUCKS' FLcctf d e n s i t y ' (faK i k u k "La ) IN FLOCK Over Total No. of 1 2 3 4 5 10 15 2 0 2 0 Flocks Over 1 0 0 1 1

901-1000 1 1

801-900 1 1 2

701-800 1 2 3

601-700 0

501-600 2 2

401-500 3 3 2 8

301-400 1 1 3 3 1 9

201-300 1 1 6 2 1 1 1

1 0 1 - 2 0 0 1 7 3 8 5 1 1 4 30

1 0 0 or less 1 6 8 2 6 4 1 1 29 i'otal No. of Flocks 2 14 26 6 27 11 2 2 6 96 -215-

EXPL.AN ATIGN CP TABLES 18 AND 19

Tables 18 and 19 show the movement of serne mallard and black, duck flocks on 0 ’Shaughnessy Re­ servoir by means of arrows as follows:

^ • movement NE , parallel to west bank

^ - movement SI, parallel to west bank

= movement E

^ - movement IV,'!

~ movement S

^ ~ movement W

= different portions of the flock moving

in opposite directions: HE and SW

same as the foregoing

same as foregoing except movement E and

W

^ different portions of the flock moving

toward a central area -213-

Table 18

MOVEMENTS OF MALLARD FLOCKS PRECEDING EVENING FLIGHTS IN 1954

DATE TIME (Arrows indicate direction of* flock movement on water

Nov. 9 1649 1655 1656 1 701 1721 1725 1726 1730 7 7 none none U 4 1732 1733 1735 7 off

Nov. 15 1719 1730 off Some disturbance.

Nov. 19 1701 1707 1710 1712 1720 1728 1730 T none ^ ^ / off

Nov. 23 1703 1715 1717 1718 1720 /* p t fi off

Nov . 29 1650 1655 1705 1706 1707 1710 St none * /» * off

Dec. 6 1651 - birds off. No previous movement noted. No di s- turbanoe noted*

Dec* 7 1705 1710 Mallards moving off shore into water. off

Dec. 13 1626 1636 1641 moving flocking near center of water. off

Dec. 14 1551 1557 1601 1605 1615 1630 some off (disturbed) 4 ^ none moving moving 1645 V off

Dec. 15 1650 1655 1658 ti 71 off Birds were disturbed and flushed on Nov. 12. Dec. 2. and Dec . 4. -219-

Table 19

MOVEMENTS OF BLACK DUCK FLOCKS PRECEDING EVENING FLIGHTS IN 1954

DATE TIME (Arrcres indicate direction of flock movement on water)

Nov. 8 1655 1656 1656 1701 1705 1718 1720 1721 />t£ moving 4, G* 7 A none

1730 1732 1735 1739 1742 1743 1744 1745 7 off off off off IT / A

Nov. 9 1710 1715 1723, 1728 off off

Nov. 12 1658 1705 1710 1715 1734 none none off Some disturbance.

Nov. 15 1719 1725 1730 to 1750 none )/

Nov..19 1701 1707 17 1 0 1 7 1 2 1 7 2 0 1 7 2 8 1750 * * none * t * off

Nov. 22 1644 1649 1700 1705 1710 off Off none off Some disturbance.

Nov. 23 1712 1715 1721 off

Dec. 6 1630 1651 1700 1707 1717 1717 1718 7 off 4 off 4 off

Dec. 14 1551 1601 1605 1615 1622 1625 1630 1640 none moving moving A off bl kf * 1645 off

Dec. 15 1650 1655 1658 * * off Bir'ds Were flushed on bee. 2, and Dec. 4. No movement was recorded preceding take-off on Dec. 7, and Dec. 13. -216-

Table 20

EXAMPLES OF FLOCK DENSITY PRECEDING EVENING FLIGHT

LA AT BEGINNING OF LAAT START OF MOVEMENT OK WATER EVENING FLIGHT

MALLARD

1-1 5 (majority) 1

1 - 4 (average) JLs dis turbed

BLACK DUCK

1 - 5 1 - 7

2 - .6 2 - 5

1 - 5 1 3 (average) 1

2 (average) 1

disturbed 1 -216-

Table 21

LIGHT INTENSITY, TEMPERATURE, AMD TIME AT START OF EVENING FLIGHTS

OF BLACK DUCKS AMD MALLARDS

T 53Pffi StfflBETTf TIKE ffM'W "TlSSnwmm f g i F T T T " DUCKS IN SUNSET IN FOOT-CANDLES DEGREES AREA CENTRIGADE

1952 Sept. 15 12 1835 1741 under 5.0 24 Sept. 16 1 1 1740 1741 under 5.0 19 Oct* 16 49 1745 1718 6.0 0 Oct. 27 242 1710 1703 25.0 19 Hcrv. 1 320 1705 1656 15.0 15 Nov. 3 12 0 1700 1654 35.0 ? Nov. 5 172 1630 1652 over 80.0 14 Dec. 1 462 1551 1633 ? -1

1953 Nov. 10 104 1655 1646 20.0 ? Nov. 18 434 1655 1639 9.2 1 Nov. 19 292 1701 1639 1.2 ? Ncrv. 21 385 1700 1637 2.0 ?

1954 Nov. 8 266 1705 1648 9.2 7 Nov. 9 310 1640 1647 190.0 10 Nov. 12 384 1704 1644 4.0 6 Nov* 14 340 1701 1643 3.6 ? Nov* 15 236 1650 1642 34.0 6 Nov. 19 376 1700 1639 3.6 ? Nov. 2 2 408 1610 1637 56.0 4 Nov. 23 517 1645 1636 10.4 5 Nov. 29 436 1640 1634 19.0 0 Dec. 2 654 ? 1633 48.0 0 Dec. 4 664 1650 1633 18.4 4 Deo. 6 240 1621 1633 240.0 3 Dec. 7 1752 1640 1633 56.0 -3 Dec . 13 450 1 6 1 1 1633 72.0 2 Dec. 14 850 1615 1633 42.0 2 Dec ■ 15 1386 1682 1634 52.0 0 Dec. 31 650 1625 1642 ? ? -217-

Table 21 cont.

LIGHT INTENSITY, TEMKBRATURE, AM) TIME AT START CF EVENING FLIGHTS OF BLACK DUCKS AND MALLARDS

BA'S® NUMBEk OF TIME T H E CF LIGHT INTENSITY TEMP. Ill DUCKS IN SUNSET IN FOOT-CANDLES DEGREES AREA CENTRIGADE

1955 Jan, 2 1123 1644 1642 58,0 8 Jan. 5 1190 1632 1646 20.0-50,0 11 Jan, 7 890 1655 1648 58.0 0 Jan. 1 0 598 1645 1651 80,0 7

Bobot Start of evening flight is taken as that time when the first group takes wing (see text far explanation).

All times in this table are solar time. -218-

Table 22

EVEKIMG FLIGHTS - HSRCENT OF TOTAL FLIGHT TAKING OFF AT VARIOUS

RANGES CF LIGHT INTENSITY

LIGHT INTENSITY IN FOOT-CANDIES DATE under ______40-35 35-50 30-25 25-20 20-15 15-10 10-5 5 1952

Sept. 15 1 0 0 Sept, 16 1 0 0 Oot, 16 1 0 0 Oot, 2 0 1 0 0 Oot* 27 68 23 9 Nov, 1 11 61 28 Nov. 3 29 71 Nov, 5 7 17 19 14 2 0 Deo, 1 24 4 4 17 28

1953

Mar , 7 1 0 0 Nov, 1 0 40 40 30 Nov, 18 54 46 Nov, 19 - - -- 1 0 0 - _ - Nov. 21 1 0 0

1954

Feb. 18 57 34 8 Feb, 26 51 11 Feb. 27 24 6 19 2 0 18 13 Nov. 9 16 18 25 Nov. 8 89 1 1 Nov. 12 1 0 0 Nov. 14 1 0 0 Nov. 15 3 41 57 Nov. 19 1 0 0 Nov, 22 2 77 Nov. 23 7 32 60 Nov. 29 15 30 33 2 2 Dec. 2 3 SO 16 12 Dec. 4 2 59 39 Deo. 6 1 - - 38 - - 18 17 Dec. 7 33 -219-

Table 22 oont.

EVENING FLIGHTS - H5RCENT OF TOTAL FLIGHT TAKING OFF AT VARIOUS RANGES OP LIGHT INTENSITY

“DATE LIGHT INTENSITY IN FOOT-CANDLES under 40-35 35-30 30-25 25-20 20-15 15-10 10-5 5 1954 Decu 13 23 2 Deo• 14 6 6 Deo • 15 44 36 1955 Jan. 2 31 5 10 19 3 Jan. 7 38 10 Jan. 10 20 18 25 3 2 -220-

Table 22 oorvfc .

EVEN IMG FLIGHTS - RECENT OF TOTAL FLIGHT TAKING OFF AT VARIOUS RANGES OF LIGHT INTENSITY

~DSTE LIGHT INTENSITY IN FOOT-CANDLES cnrer ______40-45 45-50 50-55 55-60 60-65 65-70 70-75 75 1952 Sept. 15 Sept. 16 Oot. 16 Oct. 2 0 Oot. 27 Nov. 1 Nov. 3 Nov. 5 13 9 Deo. 1 21 1953 Mar. 7 Nov. 1 0 Nov. 18 Nov. 19 Nov. 21 1954 Feb. 18 Feb. 26 38 Feb. 27 Nov. 9 41 Nov. 8 Nov. 1 2 Nov. 14 Nov. 15 Nov. 29 Nov. 2 2 8 10 1 Nov. 23 Deo. 2 48 Deo. 4 Deo. 6 5 1 18 Deo. 7 4 Deo. IS 54 18 5 Deo . 15 11 8 1955 Jan. 2 16 14 Jan. 5 Jan. 7 51 Jan. 1 0 14 13 -221-

Table 23

THE RELATIONSHIP OF LIGHT INTENSITY AT THE START OF FLIGHT TO THE

NUMBER CF MAI,LARDS AND BLACK DUCKS IN THE AREA

Hypothesis* There is no oorrelation between light intensity at the start of the flight and the number of mallards and black ducks in the area. X - Number of mallards and black ducks in the area* Y = Light intensity in foot-candles at start of flight.

X Y 1752 56 1386 52 1190 50 1123 58 932 240 890 58 850 42 o IQ n 664 19 a 654 48 598 80 r = 0.3359 517 1 0 384 4 d.f. a 28 450 72 436 19 t = 1.92 434 9 408 56 Hypothesis re; 385 2 376 4 340 4 320 15 310 190 292 12 266 9 242 25 236 34 1 2 0 35 104 2 0 49 6 1 2 5 1 1 5 -222-

Tab 1© 24

THE RELATIONSHIP OF THE TOTAL NUMBER OF BLACK DUCKS AND MALLARDS IK

TOTAL FLIGHT TO THE DURATION OF TAKE-OFF ACTIVITY

Hypothesis! There is no correlation between the number of birds in a flight and the duration of take-off activity.

X- Number of mallards and blaok ducks in the evening flight. Y= Duration in minutes of take-off activity.

X Y 409 89 496 44 172 40 957 39 456 35 1008 31 1007 30 748 30 999 27 n z 31 1079 25 339 25 r 2001 187 25 104 21 d.f* Z 29 368 15 1589 15 t - 1.094 431 15 198 15 434 14 Hypothesis aooepted 253 14 517 13 1358 10 225 10 244 8 850 5 274 5 11 5 296 4 153 7 156 1 49 1 12 1 -223-

Table 25

THE RELATIONSHIP OF THE NUMBER OF MALLARDS AND BLACK DUCKS IN AN

EVENING FLIGHT TO THE PER CENT OF THE FLIGHT THAT OCCURRED BELOW 10 FOOT-CANDIES

Hypothesisj There is no correlation between number of mallards and black duoks in an evening flight and the per cent of the flight that occurs below 1 0 -foot-candles#

X = Number of mallards and blaok duoks in the evening flight# Y * The per oent of the birds taking flight below 10 foot- oandles#

Y Y 1589 31 1358 1 1079 47 1008 7 1007 47 999 22 957 35 860 1 748 10 n a 33 654 12 517 93 r a .6532 496 1 436 77 d.f. = 31 434 100 431 45 t = 4.73 409 45 374 100 Hypothesis rejected 368 89 339 42 296 100 253 100 244 100 225 100 198 32 187 97 172 121 156 100 153 100 120 70 104 60 49 100 12 100 11 100 -224-

Tab la 26

THE RELATIONSHIP OF THE DEGREE OF CLOUD COVER TO THE AMOUNT OF TIME THE START OF EVENING FLIGHT DEVIATES FROM THE TIME OF SUNSET.

Hypothesis: There is no correlation between the time the start of the evening flight deviates from time of sunset and the de­ gree of cloud cover* X= Degree of cloud cover expressed as units of 10, Y= The time of fli^vt with respect to sunset expressed in minutes subtracted from or added to sunset. The latter has been given an arbitrary value of 60.

X Y 10 102 10 87 10 82 1 82 10 78 5 77 10 74 3 72 2 67 n r 32 10 66 10 6 6 b - 2.55 1 61 5 58 d.f. = 30 10 54 3 54 t = 3.4000 2 53 2 53 2 53 1 52 Hypothesis rejected 10 51 1 51 1 51 1 44 10 43 1 43 1 42 1 40 6 39 1 38 1 37 1 33 1 6 -225-

Table 27

THE RELATI OHS HIP OF THE DEGREE OF CLOUD COVER TO LIGHT INTENSITY AT THE STAR? OF THE EVENING FLIGHT OF MALLARDS -AND BLACK DUCKS

Hypothesi** There is no correlation between the light intensity at the start of the evening flight and the degree of cloud cover . X,*- Pagree of cloud oover expressed as units of 10. Y - Light intensity in foot-candles at the start of the evening flight.

X Y 3 240 2 190 10 80 10 72 2 58 5 58 2 56 10 56 10 52 n = 26 10 48 10 42 b ■ 1.49 1 34 2 25 d.f. » 24 1 20 10 19 t • 1.262 10 18 1 15 Hypothesis accepted 10 16 1 9 1 9 1 6 1 4 1 4 6 4 2 2 1 1 -22 6-

Table 28

THE RELATIONSHIP CF THE DEGREE OF CLOUD COVER TO THE DURATION OF

TAKE-OFF ACTIVITY IN THE EVENING FLIGHT CF MALLARDS AND BLACK DUCKS

Hypothesis There is no correlation between the degree of oloud cover and the duration of take-off activity. X - Degree of cloud cover expressed as units of 10. Y ■ Duration of take-off activity (from the first group up to the first bird of the last group taking flight).

X Y 10 89 10 44 1 40 3 39 10 35 5 31 10 30 5 27 10 30 tt ■ 29 2 25 2 25 b = 1.63 1 25 d.f. - 27 1 21 1 15 t = 2.04 2 15 10 15 Hypothesis rejected 2 15 1 14 1 14 10 13 10 10 2 10 1 8 10 5 1 5 6 4 1 7 1 1 1 1 -22 7

Table 29

THE RELATIONSHIP OF THE PER CENT OF MALLARDS AMD BLACK DUCKS IK THE EVENING FLIGHT THAT TOOK PLIGHT AT 10 FOOT-CAMPLES CSt BELOW TO THE DEGREE OF CLOUD COVER

Hypotheslsj There is do oorjssLation between the per oent of duoks in the evening flight that take off below 1 0 -focrt-candle s and the degree of oloud aover. X - Degree of oloud cover expressed as units of 10, Y = Per cent flying below 10-foot-candles.

X Y 1 100 1 100 1 100 1 100 6 100 2 100 1 100 1 100 1 100 1 100 n = 32 1 97 10 93 b = 5.25 1 89 10 77 d.f.- 30 3 70 I 60 t ■ 3.55 48 10 47 Hypothesis rejected 10 45 10 45 2 42 3 35 2 32 2 31 22 1 21 10 12 10 10 5 7 10 1 10 1 10 1 -228-

Table SO

COMPARISON BETWEEN THE DATE AND THE HSR CENT OF THE EVENING FLIGHT OF MALLARDS AND BLACK DUCKS TfLAT OCCURRED BELOW 10 FOOT-CANDIES

Hypothesist There is no correlation between the date and the per oent of the flight that ocourred below 10 foot -candles. X - The date given a numerical value based on the number of days frcta September 1, whioh has a value of 1. Y “ The per oent of the flight that occurred below 10 foot-oandles.

X Y 92 42 104 1 66 21 97 35 82 77 122 7 127 47 132 10 n ■ 33 124 22 129 48 r = .6770 70 42 66 97 d.f • = 31 71 60 62 89 t s 5.01 98 31 90 45 Hypothesis rejected 57 32 79 100 80 1 0 0 83 93 106 1 81 1 0 0 69 100 105 1 73 100 16 1 0 0 80 10 0 75 100 50 100 46 100 15 100 93 12 64 70 -229-

Table 31

THE FOMBBR OF MALLARDS AND BLACK DUCKS IH THE OBSERVATION AREA

COMPARED TO THE DEGREE OF CLOUD COVER

Hypothesis* There is no relation between the number of mallards and black duoks in the observation area and the de­ gree of oloud cover. X = Degree of oloud oover expressed as units of 10. Y - Humber of mallard and black duoks in the area.

XY 2 1752 10 1386 10 1190 5 1123 2 932 2 890 10 850 10 664 10 654 n = 30 10 598 10 517 b - 39.83 10 450 1 434 d.f. = 28 10 436 10 408 t = 0.124 2 385 1 384 Hypothesis aooepted 6 376 1 340 1 320 2 310 1 292 1 266 2 242 1 236 3 120 1 104 1 49 1 12 1 11 -230-

Table 32

EXAMPLES OF THE BEHAVIOR OF MALLARDS AND BLACK DUCKS

FLUSHED FROM THE RESERVOIR

LIGHT DUCKS DUCKS INTENSITY RESETTLING FLYING DATE IN FOOT- TIME ON RESERVOIR AWAY CANDIES

Apr. 4, 1953 1 1 , 2 0 0 1150 majority ?

Apr. 3, 1953 8 , 0 0 0 1 0 0 0 majority ?

N o t . 21, 1953 4,500 1 1 2 0 ma j or ity ?

Dec. 6 , 1952 3,000 1050 all 0

Nov. 24, 1953 2 , 0 0 0 0945 all 0

N o t . 12, 1953 1,600 1 0 0 0 all 0

Dec. 10, 1953 1 , 0 0 0 1005 all 0

Feb. 27, 1952 240 1725 7 5$ 2 5 $

Dec. 2, 1954 48 ? 8 0 $ 2 3 $

Dec. 14, 1954 14 1650 0 all

Ncrr. 18, 1952 9 1725 0 all 231-

Table 33

DIRECTION OF EVENING FLIGHTS OF MALLARDS AND BLACK DUCKS

DATE N NE E SE S SW W

1952

Sept. 15 12 Sept. 16 4 Oot. 16 49 Oct. 2 0 156 Oot. 27 135 18 180 Nov. 1 335 Nov. 3 35 75 Nov. 5 78 78 Deo. 1 134

1953

Mar. 7 80 9 Nov. 1 0 28 66 Nov. 18 396 25 7

1954

Feb. 26 509 Feb. 27 187 1 2 0 1 0 0 Mar. 5 1 6 40 136 305 Nov. 8 163 12 Nov. 9 3 5 312 Nov. 12 70 304 Nov. 14 16 137 Nov. 15 7 180 Nov. 19 12 284 Nov. 22 256 Nov. 23 203 Nov. 29 60 107 134 Deo. 2 153 2 0 235 Dec • 4 571 Dec. 6 125 671 Deo. 7 785 Deo. 9 724 529 Dec. 13 94 208 1 1 2 3 Dec. 14 2 844 4 Deo. 15 626 5 Table 33 oont.

DIRECTION OF EVENING FLIGHTS CF MALLARDS AID BLACK DUCKS

DATE N NE E SE S sW W NW

1954

Dec, 17 450 125 580 Dec, 31 24 17

1955

Jan. 2 8 14 570 2 Jan. 5 728 25 Jan. 7 979 Jan. 10 726

Total 1606 504 6153 798 3301 759 2111 1295

Notej The numbers listed refer to the number of birds flying in the direction indioated on the date gi-ren. -233-

Table 34

COMPARISON OF SEASON AND DIRECTION OF EVENING FLIGHTS OF MALLARDS AND BLACK DUCKS

1* Fall (August 1 to December 20)

N 13 E SB S sw W m

1371 464 3506 228 3187 130 1160 981

Spring (February 25 on)

N m E SE S SW W NW

203 4 0 136 0 80 629 1 0 0 305

Winter (December 21 to February 24)

N S E SE S SW w NW

32 0 2501 570 44 0 851 0

Total flying in southerly direction (S, SE, SW) in fall = 3545.

Total flying in northerly direction (IT, HE, HW) in fall - 2816.

Total flying in northerlydirection in spring * 548.

Total flying in southerly direction in fall = 709.

Notej Humbers refer to the total number of mallard and black duoks observed flying in the indicated direction. 254-

Table 35

FREQUENCY OF OBSERVATION GF

RING-NECKED DUCK, IESSEE SCAUP, AND BLACK DUCK

SPECIES FALL 1952 SPRING 1953

Ring-necked Duok 55 5,071

Lesser Soaup 258 6,934

Black Duck 24,287 3,165

Fall 1955 is based on 63 days, from Ootober 1 to December 18, Spring 1953 is based on 50 days, from January 31 to May 3. 255-

Table 56

SEX RATIO OF LESSER SCAUP OK C ’SBAUOHHESSY RESERVOIR, SPRING 1953

H R CfeKT M W ” '— FEMALES FEMAIES IN SCAUP IN SCAUP DATE FLOCKS DATE FLOCKS

March 7 24 April 1 7

March S 29 April 2 29

March 9 1 0 April 5 34

Mar oh 13 25 April 4 27

March 19 25 April 5 35

March 2 0 25 April 6 37

March 2 1 2 2 April 7 37

March 2 2 25 April 8 30

March 25 , 28 April 9 29

March 24 24 April 1 0 38

March 25 24 April 1 1 1 2

March 26 24 April 1 2 36

March 27 2 2 April IS 40

March 28 22 April 14 30

March 29 26 April 15 32

March SO 29 April 16

March 51 29 April 17 48 -236-

Table 37

RING-KECKED DUCKS AT AREAS 6 AND 7

d a t e E a Ee f e m a l e d a t e m a l e female :

March 7 68 27 April 1 ? ?

March 8 71 32 April 2 73 89

March 9 - - 71 - - April 3 34 44

March 19 49 39 April 4 ??

March 20 124 55 April 5 19 27

March 21 1 00 85 April 6 35 51

March 22 10 2 39 April 7 76 109

March 23 43 21 April 8 38 46

March 24 30 38 April 9 41 64

March 25 41 56 April 10 34 67

March 26 41 49 April 11 - 114 -

March 27 36 57 April 12 53 78

March 28 54 63 April 13 40 80

March 29 7 3 April 14 40 78

March 30 4 5 April 15 37 82

March 31 0 0 April 16 27 64

April 17 2 0 42 -237

Table 38

ORIENTATION 0? LESSER SCAUP WITH RESPECT TO WIND SPEED

WIND ORIENTATION SPEED OF SCAUP* 1270 # 1 1 1 0 # 860 0 770 # 740 # 700 # 660 # 602 # 602 0 600 # 580 # 528 0 466 # 440 # 420 # 400 £ 350 # 340 340 0 306 # 280 w 280 0 240 #

# = Birds resting on water face into wind. 0 = Birds resting on water do not faoa the wind. -238-

Table 39

EVENING FLIGHTS OF DIVING DUCKS FROM AREA 8

T5EEHEET5F " TIME OF NUMBER SPECIES DATE CLOUD COVER t a k e -o f f LIGHT* OFF COMMENTS

American March 9 1817 ? 8 merganser March 10 1825 40 1 1831 2 0 4 American March 9 1822 150 4 goldeneye 1826 ? 2 1829 90 6 1830 ? 3 March 10 1832 17 4 1833 14 2 March 12 181 f 50 2 March 13 1836 36 1 1838 1 5 March 14 1740 350 2 1804 60 1

Hooded March 9 1839 21 5 mar ganser 1849 5 1 March 1 0 1836 12" 1 March 1 2 1820 59 1 March 13 1828 1 0 0 5

Ring-necked, March 9 1819 •># 4 1854 /50** Redhead, March 1 0 1840 7 5 1843 5 1 and 1849 / 57** March 1 2 1815 55 3 Birds Lesser flushed at scaup 1817 1839 4 1845 4** March 13 * 2 Birds 1850 5 flushed at 1836,39,47 1855 / 4** March 24 1850 1 0 2 ** April 1 1846 8 1 ** * Lxglit nea'sured in foot-candles. / = Light intens ihy under 5 foot- candles ** First group off* This was followed by others until all ducks were out of the area. -239-

Table 40

FREQUENCY OF OBSERVATION CP SHOREBIRDS

SPECIES 1952 1953

Semi palma ted Plover 237 51

Killdeer 2719 2523

Golden Plover 16 28

Black-bellied Plover 1 0 0 65

Ruddy Turnstone 1 0

Woodoook 0 1

Wilson*s Snipe 4 3

Upland Plover 3 0

Spotted Sandpiper 98 36

Greater Yellow-legs 70 72

Lesser Yellow-legs 105 49

Knot 0 9

Pectoral Sandpiper 883 528

White-rumped Sandpiper 0 4

Baird’s Sandpiper 4 6

Least Sandpiper 599 186

Dunlin 293 365

Dswitcher 19 13

Stilt Sandpiper 184 . 9

Semipalmated Sandpiper 596 61

Western Sandpiper 19 3 Table 40 corrfc .

FREQUENCY OF OBSERVATION OF SHORE BIRDS

SIEClES 1952 1953

Buff-djreasted Sandpiper 0 1

Sander ling 7 0

Avocet 0 6

Wilson's Phalarope 0 1

Northern Phalarope 1 7

jDOTAl 5958 4024 -241-

Tabl© 41

TOTAL HOURS SPENT IN THE FIELD ON SHOREBIRD

OBSERVATIONS AT A GIVEN HOUR

Tllte OF DAY TOTAL NUMBER OF HOURS TN THE FIELD

0400-0500 0.75

0500-0600 1 . 0 0

0600-0700 4.00

0700-0800 4.50

0800-0900 14.75

0900-1000 49.75

1 0 0 0 - 1 1 0 0 51.00

1 1 0 0 - 1 2 0 0 24.75

1200-1300 13.00

1300-1400 2 . 0 0

1400-1500 8.50

1500-1600 11.25

1600-1700 12.50

1700-1800 12.25

1800-1900 16.75

1900-2000 8 . 0 0

TOTAL 234.50 -242-

Table 42

FREQUENCY OF OBSERVATION OF PECTORAL SANDPIPER

AT O'SHATJGHNESSY RESERVOIR - 1952

DATE ~ JUIY AUGUST SEPTEMBER OCTOBER NOVEMBER

1 10 2 13 5 7 3 * 16 5 9

4 17 9

5 37 10 1*

6 10 15 27 9

7 8 15 34 3

8 8 12

9 8 21 3

10 * 3 31 11 13 24 0

12 20 12 41*

13 78 14 32

14 16*

15 39 19 26

16 14 27

17 * 9 30

18 41 6 47 19 23 24*

20 22 0* 18 -243-

Table 42 cont*

FREQUENCY CF OBSERVATION OF PECTORAL SANDPIPER

AT 0 1SHAPGHNESSY RESERVOIR - 1952

b a s e JULY AUGUST SEPTEMBER OCTOBER NOVEMBER

2 1 22 0 * 18

2 2 19 26

23 30 1 0 13

24 15* 2

25 2 4 4

28 2 1 2 *

2 1 19

28 3 8 * 8

29 10 1 0

50 18 18 4 0

31 18 - 5 -

* Sunday ■244 -

Table 42a

FREQUENCY OF OBSERVATION OF PECTORAL SANDPIPER

AT 0 * SHAUGHKESSY RESERVOIR - 1953

DATE JULY ATJI-UST SEPTEMBER OCTOBER NOVEMBER

1 1 0 0

2 0 0

3 0 1 2

4 0 2 1

5 2 6 0

6 0 8

7 2 5 5

8 0

9 0 1

10 0

11 0 7

12 0 1

13 0 5

14

15 0

16 3

17 3 9

18 0 28

19 0

2 0 1 -245-

Table 42a aotrt.

FREQUENCY OF OBSERVATION OF PECTORAL SANDPIPER

AT O ’SHAUGHNESSY RESERVOIR - 1953

w “julz Au gu st septembW o c I O T K n o v e m BER

21

22

23

24 2 0

25 0 5

26 0 5

27 7

28 2 1

29 6 4

30 1

31 0 5 -246-

Table 43

FREQUENCY OF OBSERVATION OF LEAST SAMD PI PER

AT O ’SHAUGHNESSY RESERVOIR - 1952

'S/HE 'JtiCf AlfeTTsY S m E H B W "“ggTCBBB"' "WTSSESST

1 30

2 7

3 26

4 14

5 24 16

6 9

7 2 1

8 4

9 2

10 10

11 9

12 9

13 57 10

14 9

15 3 6

16 5

17 4

18 45 4

19

20 1 -247-

Table 43 oont.

FREQUENCY OF OBSERVATION OF LEAST SANPPIHIR

AT 0 1SHAOGHNESSY RESERVOIR - 1952

DATE JULY AUGUST SEPTEMBER" OCTOBER NOVEMBER

21 21

22 43

23 7

24 -29

25 2

26 30

27 33

28 26

29 17

30 14

31 37 -248-

Table 43a

FREQUENCY OF OBSERVATION OF LEAST SAMPPISB RS

AT O'SHAPGHHESSY RESERVOIR - 1953

dIte 1 W H r August seFtEmeS octoeeI November 1 16 1 2 15 3 2 4 5 5

6 6 7 8 1 8 1 9 4 10 4 11 4

12 6 13 3 14 5 15 1 16 5 17 10 18 9 19 1

20 -249-

Table 43a cont*

FREQUENCY OF OBSERVATION OF IE AST SAID PIPERS______

AT O'SHAUOHIBSSY RESERVOIR - 1955

d IH ' "inns' Au g u s t septEm b e R c c t o b e r No v e m b e r

21

22 4

23

24 0

2.5 1

26 1

27

28 2 7

29 5 9

30 7

si 9 mm -250-

Table 44

FREQUENCY OF OBSERVATION OF SEMIPAI21ATBD SANDPIPER

AT O'SHAUGHNESSY RESERVOIR - 1952

DATE " JUIY AUGUST ' SEPTEMBER OCTOBER NOVEMBER 1 25 2 45 3 35

4 3 5 4 15

6 1 22

7 25

8 18

9 35 10 39 11 27 12 16 21 13 9 14 10

15 4 10

16 19 17 5 18 15 2

19 4

20 -251-

Table 44 oont,

FREQUENCY OF OBSERVATION OF SBMIFALMATEP SAKPPIFER

AT 0 * SHAUGKNESSY RESERVOIR - 1952

DATE JULY AUGUST SEPTEMBER OCTOBER NOVEMBER"

2 1 16

22 14

23 3 0

24 20

25 1 6

26 14

27 10

28 7 5

29 16

30 5 26

31 45 - -252-

Table 44a

FREQUENCY OF OBSERVATION OF SBKIPAIMATED SARD PIPER

AT O'SHAUGHMESSY RESERVOIR - 1953

DATE______JULY AUGUST SEPTEMBER OCTOBER NOVEMBER 1 2

3

4

5 6 1

7

8

9 2

10

11 2

12 1

13 1

14 2

15 9

16 2

17 2

18

19

20 5 -253-

Table 44a cont.

FREQUENCY OF OBSERVATION CF SEMIPAIMATBD SAKDPIFER

AT O ’SBADOHNESSY RESERVOIR - 1953

T O E JUHf AUGUST SEPTEL®ER 'OCTOBEli ¥ 6VEKBER

21

22 3

23

24

25

26

27

28 2

29

30

31 -254-

Table 45

WATER IEVELS M G ’SEAUGKNESSY reservoir

Iwmiarwssst W m i MONTH 1952 1 953 1954

July 847.58 847.61 847.58

Aug. 844.17 847.71 847.64

Sept. 840.96 844.07 847.74

Oct. 837.82 839.40 845.74

Nov. 835.41 836.61 846.74

NET CHANGE IN WATER IEVEL, FIRST OF MONTH AS COMPARED TO LAST OF MONTH MONTH 1952 1953 1954

July -1.24 /0.17 -1.37

Aug. -3.68 -2 . 1 2 /1.76

Sept. -2.62 -2.87 -4.13

Oot. -3.03 -5.04 /3.75

Nov. -0.72 /0.37 -0.47 -255-

Table 46

FREQUENCY OF OBSERVATION OF SHOP, E BIRDS

COMPARED TO WATER IEVELS AT O'SHAUGHNESSY IN THE FALL

~ s v e o s e *'~ BIRDS n u MBEE o!f days YEAR WATER LEVEL FEE DAY OF OBSERVATION (FALL ONLY)

840.15 47.5 82 1952

841.23 29.8 23 1951

842.60 17.0 58 1953

844.08 11.5 13 1948

846.35 4.8 14 1954

847.86 2 . 8 10 1949

848.05 13.5 8 1950

Birds per day - number of shorebirds (exolusive of killdeer) divided by the number of days on which shore- birdB were observed.

Average water level » average of water level of the 1st and 15th days of each month from August 15 to November 1 , -256-

Tablo 4 7

FREQUENCY OF OBSERVATION OF KILIDEER COMPARED TO WATER IEVELS

AT O'SHAUGHNESSY IN HIE FALL

AVERAGE BIRDS NUMBER OF DAYS YEAR WATER LEVEL FER DAY OF OBSERVATION (FALL ONLY)

840.15 31.6 8 6 1952

841.23 57. S 23 1951

842.60 35.7 62 1953

844.08 28.6 14 1948

846.35 50.9 15 1954

847.86 14.0 15 1949

848.05 37.7 11 1950

Birds per day * number of shore birds divided b y the number of days on which shorebirda were observed.

Average water level = average of water level of the 1st and 15th. days of eaoh month from August 15 to November 1. Table 48

FREQUENCY OF OBSERVATION OF DUNLIN COMPARED TO WATER LEVELS

AVERAGE BIRDS NUMBER” OF DAYS YEAR WATER LEVEL p m DAY OF OBSERVATION (FALL ONLY)

840.15 13.3 22 1952

841.23 14.5 1 0 1951

842,60 15.6 23 1953

Birds per day = number of shorebirds (exclusive of killdeer) divided by the number of days on nhioh shore­ birds were observed.

Average water level « average of water level of the 1st and 15th days of each month from August 15 to November 1, -258-

Table 49

CHANGES IN NUMBERS OF SECTORAL SANDPIIER AT 0»SllAUl-H2SSSY

NUMBER OF SUMMARY OF ______BIRDS * WEATHER1 COMMENTS 1952 Aug. 4 17 78 Cold front Aug. 4-5

Aug. 5 37 67,<§T

Aug. 6 10 69S ®

Aug. 7 TO#''"

Aug. 12 2 0 68 Cold front Aug. 10-11 < Aug. 13 78 64 Cold front Aug. 12-13

Aug. 14 7 66

Aug. 15 39 67

Aug. 22 19 70 | Cold front Aug. 21-22 Aug. 23 30 75 6 Aug. 24 15 80 6 Aug. 25 ? Aug. 26 2 1 85 cr Aug. 27 19 85 cr Aug. 28 3 75

Sept. 5 10 54

Sept* 7 15 72

Sept. 8 84 0

Sept. 9 78 © Table 49 oont.

CHANGES IN NUMBERS OF PECTORAL SANDPIPER AT O ’ SHAUGHNESSY

DATE NUMBER COP SUMMARY OF BIRDS * m A T H E R 1 COMMENTS 1952 Sept. 10 3 76 C f ~

Sept, 14 16

Sept, £6 19 14

Sept. 16 14 67 "

Sept. 17 9 67

Sept. IS 6 72 Sept. 19 23 63 $ Cold front Sept. 19 Sept. 20 0 7 0 V ( 5 Sept. 21 0 70 % Oot. 5 1 Mild cold front Oct. 5

Oct. 6 27 4 6 ^ J ®

Oot. 7 34 A 43

Oot. 8 12 A 60 5 Oot. 9 21 AB 62 ( 4 ___

Oot. 10 31 AB 48 ®

Oot. 11 24 AB 52 ©

Oot. 12 41 ABC 52

Oot. 13 32 ABC 561) Cold front Oct. 13-14

Oct. 14 ? AB 58 d 3

Oot. 15 26 AB 44 ^

Oct. 16 27 AB 4 2 ^ 3 Cold front Oot. 16 -260-

Table 49 oonfc •

CHANGES IN NUMBERS CP PECTORAL SANDPIPER AT 0'SHADGHKESSY

1>AtE fOHSER cF summary of BIRDS * WEATHER1 C CU E NTS

1 9 5 2 ^ Oot. 17 30 AB 46 Q

Oct. 18 47 AB 42

Oct. 19 24 B 52 Oct. 20 35 B 4 0-S1 3 Cold front Oct* 19-20 Oot. 21 18 B 38 D

Oot. 22 26 B 4 0 ^ 0

Oot. 23 13 52 6

Oot. 24 2 5 0 M 3

1955 Oot. 17 9

Oct. 18 28 (?)

Oct. 24 20 5 2 V A K w Oct. 25 5 58

* Letters after cumber of birds refer to narked individuals.

1 Temperature given in degrees Farenheit, so that comparisons may be made with U.S. Weather Bureau Data.

Fear key to symbols see Appendix II -261-

Table 50

INCREASES OF PECTORAL SANDPIPER COUNTS FOLLOWING

PASSAGE OF COLD FRONTS IN THE FALL OF 1952

DATE OF COUNTS OF PECTORAL SANDPIPER* FRONTAL BEFCRE 1ST DAY 21® DAY 3RD DAY PASSAGE PASSAGE AFTER AFTER AFTER

8 Aug, 14 17 1 2 1 0

Aug, 12 2 0 78 ? 39

Aug, 21 22 19 50 15

Sept,19 6 £ 2 0 0

Oot, 6 1 27 34 12

Oct, IS 32 ? 26 27

Oot. 16 27 30 47 24

Oct. 19 24 55 18 26

* Highest count is underlined -262-

Table 51

CHANGES IN NUMBERS CF LEAST SANDPIPERS AT O'SHAUGHHESSY

DATE NUMBERS* we a t h e r COMMENTS 1952 Aug, 4 14 70 • Cold front Aug, 1-6

Aug, 5 24

Atg. 6 ? 69

Aug, 7 2 70 #

Aug, 21 2 1 69 ^ Cold front Aug, 21-22

70Aug, 22 43 70Aug,

Aug, 23 7 75 ( 5 r* Aug, 24 29 80 O

Aug. 27 33X

Aug. 28 2 SX 76 Cl- \ Aug. 29 ITS B0J* Aug, 30 14X 75J* Aug. 31 37 " J ® Sept. 1 30 90J © Cold front Sept, 1-2 Sept, 2 7 62 ^ / Sept. 5 26 62 O Sept* 4 ? so (5 Sept. 5 16 54 © Sept. 6 9 80 o Weak cold front Sept, 6-7 Sept. 7 1 72 -263-

Table 51 oont*

CHANGES IN NUMBERS OF IEAST SANDPIPERS AT 0*SHAUGHNESSY

DATE NUMBERS* 'WEATHER C0MM3NTS 1953 Aug* 30 7

Aug* 31 9 Sept. 1 16 © Sept* 2 15 ©

* X refers to the continued presence of one individual sandpiper. -264-

Table 52

CHANGES IN NUMBERS OF SEMIPALMATED SANDPIPERS AT 01SHAUGHNESSY

WE3HK " (TM bnts " 1952 Aug. 23 3 75 ( j C old fro nt Aug . 21 -22

Aug. 24 2 0 80 6 Aug. 29 16 80°J* Aug. 30 26 75IP Aug. 31 45 65It Sept. 1 38 90o £ ) Cold front Sept# 1-2

Sept. 2 42 62 ^ Sept* 3 35 62 5 Sept. 4 ? 50

Sept. 5 15 64 (Q) Weak oold front Sept. 6-7

Sept. 8 18Z 84 n C

Sept. 9 35X

Sept. 1 0 3SK 76 ( J

Sept. 11 27X 86 ©

Sept. 12 21X 94

Sept. 13 99 87 Q >

Sept. 14 10

Sept. 15 1 0 76 Cold front Sept. 15-16

Sept. 16 19 6? 0 Sept. 17 5 67 -265-

Table 52 oont,

CHANGES IN NUMBERS OF SEMIPALMATED SANDPIPERS AT O'SHAUGHNBSSJT

d a t e NXJMBEfeS* WEATHER COlfflfeiJTS 1952

Sept* 18 2 72 ( b

★ X R e f e r s to the oontinued presence of one individual. Table 53

CHANGES IN NUMBERS OF DUNLINS AT 0*SHAUGHNESSY

T5STE WM b W s ts&AtKB* comnents 1952

Cot, 19 17 24f\_) Cold front Oot, 19-20

Oot, 2 0 2 1 4 O j 0

Oot, 2 1 26 38

Oot, 22 21

Oot, 23 15 52

Oct, 24 18 5 0 » O Oot, 25 14 56 cT Cold front Oot, 25-26 Oot, 26 15 50,, c T Cold front Oot, 26-27

Oot, 27 7 66

Oot, 28 14 41 ■ 2

Oct, 29 13 33 £

Oct, 30 1 0 38* o Oot, 31 3 Nov, 1 5 7 fo

1953

Oot, 30 30 48 ©

Oct, 31 35

Nov. 1 26 Nov, 2 32 IP Nov, 3 35 ocKD -267-

Table 53 oonb •

CHANGES IN NUMBERS OF DUNLINS AT O'SHAUOHNESSY

~~ ]PATE ' NUMBERS ~ W A T H E & ~~....~.~ C O W m f F S

1953

Hcrv* 4 23 42

Nov* 5 ? Nov. 6 3 32 d -268-

Table 54

NUMBER OF BIRDS IN FLY-OFFS (All Areas)

LIGHT INTENSITY OF SPECIES DATE TIME IN FOOT-CANDIES BIRDS IN FLY-OFF

Semipalmated Plover 1952 Sept. 15 1647 4800 1 1 Sept, 6 1820 1 0 0 4 Sept* 16 1918 2 2 1953 Aug* 23 1900 1 0 0 1 Aug. 23 1910 38 2 Aug. 24 0900 1 1 Aug, 24 1846 350 7

Black-bellied Plover 1952 Oot. 7 1826 go 4 Oot, 7 1840 * 2 Oot. 26 1005 7 3

Spotted Sandpiper 1952 Aug. 24 1930 7 2 Sept. 16 1921 * 1 Sept. 23 1842 * 3

Greater Yellow-legs 1952 Oct. 27 1805 5 18

Lesser Yellow-legs 1952 Sept. 2 1531 3200 4 Sept. 13 1912 5 1 1953 Sept. 4 0845 4200 2 Sept. 21 1843 3 6 Sept. 26 0650 7 6

Pectoral Sandpiper 1952 Aug. 13 1925 25 8 Aug. SO 1745 60 1 Sept. 13 1900 4 4 -269-

Table 54 cotit •

NUMBER OF BIRDS IK FIX-OFFS (All Areas)

LlGflr INTENSITY NUMBER CF SPECIES DAIS TIME IN FOOT-CANDLES BIRDS IN FLY-OFF

Pectoral Sandpiper 1952 (o onfc inued) Sept. 14 1145 9000 5 Sept. 15 1815 250 4 Sept. 15 1914 5 5 Sept. 15 1917 * 5 Sept. IT 0925 7000 6 Sept. 19 1825 250 4 Oot. 16 1821 4 6 Oot. 17 0845 2400 9 Oot. 20 1808 4 2 Oot. 20 1700 1 0 0 0 15 Oot. 28 1 0 2 0 4000 2 1953 Sept. 21 1855 * 20 Sept. 21 1858 * 7 Sept. 21 1859 * 9 Sept* 21 1906 * 2 Sept. 25 1602 2600 17 Sept. 26 0620 35 8 Sept. 26 0625 60 6 Sept. 26 0630 80 37 Sept. 26 0644 160 4 Oot. 24 1015 ? 3

B aird1s S and piper 1953 Aug. 24 1935 5 1

Least Sandpiper 1952 and Aug. 24 1915 5 20 Semipalmated Sand pi per Aug . 24 1917 5 2 Aug. 30 1715 1 0 0 7 (included together Aug. 30 1840 60 4 as it was often Aug. 30 1850 60 2 diffioult to distin­ Sept. 1 1619 6800 5 guish between these Sept. 2 1600 6000 1 0 two species at low Sept. 6 1850 60 2 0 light intensities) Sept. 8 1845 50 1 Sept. 8 1850 50 14 -2 70-

Tab la 54 corrb.

NUMBER OF BIRDS IN FLY-OFPS (AIL Areas)

Light intensity NUMBER CF SIECIES DATE TIMS IK FOOT -CANDLES BIRDS IN FLY-OFF

Least Sandpiper 1952, and Sept, 8 1854 50 4 Semipalmated Sept, 9 1903 2 0 2 0 Sandpiper Sept, 9 1915 2 18 Sept, 10 1849 55 4 (ootrb inued) Sept• 10 1915 5 14 Sept, 12 1850 50 2 Sept, 12 1917 5 9 1953 Aug, 22 1830 1 0 0 0 1 Aug, 22 1920 170 1 Aug, 22 1955 2 2 0 Aug, 23 1910 48 4 Aug, 24 0900 ? 3 Aug, 24 1846 350 6 Aug, 24 1935 5 1 Aug, 24 1945 * 1 Sept, 1 0905 7000 4

Dunlin 1952 Nov. 2 1215 5600 1 0

Stilt Sandpiper 1952 Aug, 30 1630 2 0 0 0 4 Sept, 3 1055 8000 4 Sept, 7 1205 9500 4 Sept, 9 1900 40 2 Sept, 9 1905 40 3 Sept, 10 1832 1 0 0 5 Sept, 10 1833 1 0 0 4 Sept. 15 1725 300 1

* Light intensity does not register on meter (intensities below 0 * 1 foot-aandles• ? Light Intensity not measured, but estimated to be above 100 foot- candles. -271-

Table 55

RECORD OF PROCEDURE - TEST 0!®

DATE FEEDING Am T.* AMT.* tEMp . at TIME TEMP. COMMENTS TIME FED EATEN FEEDING OF OBS. AT OBS.

Series 1. Lights on 0530 to 1730.

Mar. 11 1600 .75 .75 20° C 1700 20° C

Mar. 12 1400 .75 .75 20° C 1700

Mar. 15 0800 .75 .75 2 0 ° c 1700 25° C

Mar. 14 1500 .75 .75 1700 20° C

Mar* 15 0900 .75 .75 17° C 1700 18° C

Mar. 16 0700 .75 .75 1700 20° C

Mar. 17 1 1 0 0 .75 .50 18° G 1700 21° C

Mar. 18 1 0 0 0 .75 .0 0 1700 23° C

Mar. 19 1 2 0 0 .75 .75 1700 25° C

Mar. 20 1500 .75 .75 1700 23° C Ducks removed

Series 2. Lights on 0530 to 1730.

Apr. 6 1 2 0 0 .50 .50 1700 24° C

Apr. 7 1 2 0 0 .50 .00 1700 21° C

Apr* 8 1 2 0 0 .50 .0 0 1700 21° C

Apr. 9 1130 .50 .50 1700 21° C Ducks left in chamber• Series 3, Lights on 0430 to 1630.

Apr. 14 1 0 0 0 .50 .50 1030

Apr * 15 1 2 0 0 .50 .25 29° C 1500 29° C

Apr. 18 1030 .50 .50 20° C 1 0 0 0 19° C -272-

Table 55 o out •

RECCED OF PROCEDURE - TEST ONE

DATE FEEDING AMT.,* Am T.* t e m p . At TiMfc TEMP. TIME FED EATEN FEEDING OF OBS. AT OBS. COMMENTS Series 3. Lights on 0430 to 1630 (Continued) Apr. 19 1045 .50 .50 24°G 0940 21°C-No change in light made* Apr. 19 1605 29°C-Light decreased

Apr. 20 1130 .50 .50 1550 31°C

Apr. 21 1030 .50 .50 25°C 1605 32°C Apr. 27 1130 .50 .50 27°C 1500 30°C Copulations attempted by Apr. 28 1130 .50 .37 0900 21°C four of the five drakes Apr . 29 1130 .50 .50 1 2 0 0 22 C on the remain­ ing drake. Apr. 30 1130 .50 .50 1300 28°C

May 3 1130 .50 .50 1600 17°C-0ne duck removed Series 4. Four ducks only. Lights on 0430 to 1630. 4 1130 .40 .40 0905 13 °C May 5 1130 .40 .40 1605 17°C May 7 1130 .40 .40 1610 20°C

May 8 1130 .40 .40 1640 20°C

May 10 1130 .40 .40 1600 18 °C May 10 1350 18°C-No change in light. Three Series 5. One duck only. Lights on 0430 to 1600.^ ducks removed. May 18 1130 1550 30 °C May 19 1130 1600 24°C May 20 1130 1550 24 °C May 21 1300 1600 27°C

★ Amount of food given in pounds, # Food was maintained in the food tray thougbout series 5, -273-

Table 56

RECORD OF PROCEDURE - TEST TWO

FEEDING M r . * M&.* tfEKP. AT T BE TEMP. DATE TIMS FED EATEN FEEDING OF OBS. AT OBS. COMMENTS Lights ion from 0330 to 1530 Jan . 3 0947 .50 .25 22°C 1455 22 °C-No change in light. Jan.4 0935 ,50 .00 22 °C 1455 22 °C

Jan. 5 0940 .50 .10 20°C 1455 2 2 °C-No change in light. Jan. 6 0938 .50 .25 21°C 1455 22 °C

Jan. 7 0945 .50 ,25 21°C 1455 21°C-No change in light. Jan. 8 0940 .50 .50 20°C 1455 21°C

Jan. 9 0932 .50 .19 21°C 1455 2 2 °C-No change in light. Jan. 10 0806 20°C-No change in light. Jan. 10 0842 20°C-No change in light. Jan. 1 0 0937 .50 .44 22 °C 1455 22 °C

Jan. 11 0935 .50 .31 21°C 1455 22°C-No change in light. Jan. 12 0937 .50 21°C 1455 22°C- Ducks removed. 274-

Table 57

RESULTS OF TEST ONE - THE TOTAL NUMBER OF LIKES CROSSED BY ALL DUCES IE EACH SUCCESSIVE FIVE-MINUTE PERIOD

Series I

DAT OF NUMBER OF LINES CROSSE*) IN EACH FIVE MINUTE PERIOD* TEST (9) (8 ) (7) (6 ) (5) (4) (3) (2 ) (1 )

1 0 13 16 1 0 4 6 18 2 0 19

2 5 15 24 28 147 125 145 70 82

3 5 16 1 12 52 91 141 54 65

4 1 0 7 29 63 45 26 9 77 84

5 56 27 1 1 0 0 1 79 150 160

6 0 0 0 0 0 29 0 23 128

7 0 1 1 2 1 16 32 1 1 19 1

S 2 0 40 1 0 1 1 0 2 0 8

9 0 0 0 0 0 25 84 73 63

1 0 18 28 2 0 13 48 67 2 78 1 0 1

*F0 tAL 114 147 1 1 2 148 313 402 491 564 711

* Numbers in parenthesis refer to the number of lights on during each period and hence to the light intensity. -275-

Table 57 oont.

RESULTS OF TEST OKE - THE TOTAL NlflffiBR OF LINES CROSSED

BY ALL DUCKS IN EACH SUCCESSIVE FIVE-MIKUTE FERTOD

Series 2

FJCT OF"" i t m r W TT W s CROSSED iR feACH FlfrE m i RittS; m i o t ) V TEST (9) (8 ) (7) ( 6 1 (5) (4) (3) (2) (1 ) 1 0 0 0 4 0 7 7 23 26

2 1 25 155 183 212 72 125 16 114

3 5 1 0 0 0 110 51 23 32

TdffAt 6 26 155 is 7 2l£ T 8 § l'SS 62 IT'S

* Humbers in parenthesis refers to the number of lights on during eaoh period and hence to the light intensity. -276-

Table 57 oont *

RESULTS OF TEST ONE - THE TOTAL NUlfflER OF LINES CROSSED BY ALL DUCKS IN EACH SUCCESSIVE FIVE-MINUTE FERIOD

Series 3 t m of NUNfBfijR 01’ LINES CROSSED IN EACH FIVE MINUTE PERldD* TEST <9> (8 ) (7) (6 ) (5) (4) (3) (2 ) (1 )

1 0 0 0 0 0 0 23 12 5

2 18 35 49 72 12 0 162 191 292

3 1 0 2 2 6 0 9 2 7 0 15

4 29 25 9 14 51 50 98 83 104

5 9 0 73 39 26 45 83 97 73

6 3 45 36 5 9 11 2 2 2 0 75 2 0 2

7 2 7 46 19 33 8 6 6 8 8 109

3 3 1 3 0 0 2 9 0 39

9 1 3 0 0 0 13 12 17 4

1 0 0 0 0 0 12 3 0 53 1 2 1

1 1 1 1 26 48 147 105 11 2 44 179 145

TOTAL 8 6 164 270 296 257 347 724 795 1109 * Numbers in parenthesis refers to the number of lights on during eaoh period and hence to the light intensity. -277-

Table 57 Cont.

PESULTS OF TEST ONE - THE TOTAL NUMBER OF LITES CROSSED

BY ALL DUCKS IK EACH SUCCESSIVE FIVE-MINUTE PER I OP Series 4

DAY OF HUMBER OF LINES CROSSED IN EACH FIVE MINUTE PERIOD* TEST O) .. (8) _ (7) (6) (5) (4) (3) (2) (1) 1 6 48 51 79 26 60 0 0 15

2 0 0 0 35 64 142 75 0 166 3 0 0 0 17 38 lie 108 97 48

4 0 1 0 0 13 30 12 20 10 5 23 36 21 00 0 0 99 84 64 , .g0j TOTAL 29 85 72 l3i 141--- 350' 294 308 Series 5

DAY CJF NUMBER OF LINES CROSSED IN EACH FITE MINUTE PERIOD* TEST (9) (8) (7) (6) (5) (4) (3) (2) (1) 1 5 1 0 0 0 6 3 0 18

2 0 0 0 0 0 0 0 21 61

3 59 36 5 3 0 2 0 8 57

4 0 0 0 1 0 6 0 24 65 fC*AL 64 37 5 4 0 14 3 53 20l * Numbers in parenthesis refers to the number of lights on during each period and hence to the light intensity. -278-

Table 58

RESULTS OF TEST TWO - THE TOTAL NUMBER OF LINES CROSSED

BY ALL DUCKS IN EACH SUCCESSIVE THREE-MINUTE PERIOD

DAY CF WITH NO CHANGE IN LIGHT INTENSITY* TEST (1 2 ) (1 2 ) (1 2 ) (1 2 ) (1 2 ) (1 2 )

1 65 1 5 0 0 0

5 0 0 0 0 98 142

5 1 1 0 0 0 58

7 5 0 1 6 106 84 69

9 26 6 0 0 5 4

YCtAl 97 8 21 106 187 275

DATE OF WITH NO CHANGE IN LIGHT INTENSITY* TEST (1 2 ) (1 2 ) (1 2 ) (1 2 ) (1 2 ) (1 2 )

1 0 8 0 0 14 13

3 114 2 1 2 2 39 44 8

5 126 61 38 12 33 18

7 104 83 78 32 37 9

Q 6 37 1 1 0 134 55 4

TOTAL 350 2 1 0 248 277 183 52 * numbers in parenthesis refers to the number of lights on during eaoh period and hence to the light intensity. Table 58 Cent .

RESULTS OF TEST TWO - THE TOTAL NUMBER OF LINES CROSSED

BY ALL DUCKS IN EACH SUCCESSIVE THREE-MINUTE PERI CD

DATE OF WITH DECREASINC- LIGHT INTENSITY * TEST (1 2 ) (1 1 ) do) (9) (8 ) (?)

2 0 7 0 0 0 27

4 3 0 55 234 157 104

6 28 18 12 0 0 0

8 7 8 17 0 2 17

1 0 14 77 63 4 0 7

TOTAL “ 52 ilo 147 238 159 155

DATE OF WITH DECREASING LIGHT INTENSITY* TEST (6 ) (5) (4) (3) (2 ) (1 )

2 64 61 170 305 216 2 2 1

4 138 1 119 128 169 234

6 0 0 102 77 114 156

8 182 117 188 174 256 25

10 104 163 96 146 116 5

TOt-Ai," 488 342 675 830 871 641

* Numbers in parenthesis refers to the number of lights on during each period and hence to the light intensity. -280-

Table 59

TEMPERATURE AND FOOD CONSUMPTION COMPARED WITH ACTIVITY

OF FIVE MALLARDS DURING THE TEST PERI®

WEIGHT OF FOOD TEMPERATURE TOTAL CONSUMED IN AT TEST PERIOD ACTIVITY * FEEDING FERIOD # DEGREES CEKTRIGRABE FOR TEST .75 20 106

.75 ? 641 .75 25 437

.75 20 484

.75 25 245

.75 23 375

.50 21 102

.50 24 67

,50 21 222 to o . a 445

.50 32 707

.50 17 817

.25 18 484

.25 20 180

.00 23 82

.00 21 903 Hf # Given in pounds. * Records taken from results of both tests I and II* FIGURES 282-

FIGURE

O'SHAUGHNESSY RESERVOIR

NUMBERS REFER TO OBSERVATION AREAS

LIMITS OF AREAS ARE SHOWN BY DOTTED LINES

SCALE l“ * 3 & 0 0 * -283-

io o o

FIGURE 2

O'SHAUGHNESSY RESERVOIR

9 0 0

WATER AREA IN RELATION TO WATER LEVEL

tr

u.

7 0 0

6 0 0

500

1— 8 5 0------8 4 0------—— ------—830----- WATER LEVEL IN FEET ABOVE SEA LEVEL -284- FIGURE 3

JULY —AUGUST rSEPTEMBER-j—OCTOBER NOVEMB£R-r-DECEMBER1

848

7 \\ r 847

846 O' SHAUGHNESSY RESERVOIR 845 LlI

8 4 4 VELSATER

1952 843 1953’ til 1954

842

ui UJ 841 u.

Hi

UJ

839 Ui

8 3 8

837

836

835

■JULY ■AUGUST—^-SEPTEMBER-1—OCTOBER-1-NOVEMBER-*-oecEMBE FIGURE 4 •285- O'SHAUGHNESSY RESERVOIR

WATER LEVELS AND NUMBERS OF BLACK DUCKS 849 3 0 0 0

648

2500

846 m > UJ 844 2000 < Ui Ui UJ o> cn< 842 »- Ui UJ 1500 il.

col

UJ NUMBER OF DUCKS w 840 _l

IE lit IOOO i

838

836

834 20 25 30 -286- FIGURE 5

SCHEMATIC REPRESENTATION OF AERIAL VIEW OF FLOCKS OF BLACK DUCKS AND MALLARDS

AREA 5 - NOV. 19, 1952 AT 1500 HOURS

^ DUCKS ON SHORE

AREA 5 - NOV. 29, 1952 AT 1135 HOURS

AREA 5 - DEC. f6, 1952 AT 1030 HOURS

MUD FLAT

DUCKS ON SHORE

AREA 5 - TYPICAL FLOCK PATTERN PRECEDING EVENING FLIGHT

■a-. ■nmut

NOTE’ IN ALL OF THE ABOVE ONE DOT - ONE DUCK NUMBER OF BIRDS 35 30 20 25 OCTOBER 20 RQEC O OBSERVATION OF FREQUENCY 'SAGNSY RESERVOIR O' SHAUGHNESSY NOVEMBER DUNLIN -• 1953 ---• 1952 1951

20 FIGURE LEAST SANDPIPER AND SEMIPALMATED SANDPIPER SUMMARY OF YEARS 1948 TO 1954 O'SHAUGHNESSY RESERVOIR

SEE TEXT FOR EXPLANATION

50 LEAST SANDPIPER SEMIPALMATED SANDPIPER

40

30

20

JULY AUGUST SEPTEMBER OCTOBER NUMBS.ft OF BIROS PER HOiU*» IN F L Y -O F F S oo so o IRA ATVT A MEASURED AS ACTIVITY DIURNAL Y FLY-OFFS BY EP SANDPIPERS PEEP □ mm L SPECIES ALL OR O DUNL PERIOD DIURNAL OF HOURS 2000

6®Z" B 3W00IJ LIGHT INTENSITY AND FLY-OFFS

PERCENT OF BIRDS IN FLY-OFFS ■ LIGHT INTENSITY BELOW 100 FOOT-CANDLES > PERCENT OF BIRDS IN FLY-OFFS □ LIGHT INTENSITY ABOVE 100 FOOT-CANDLES

PERCENT OF TIME IN FIELD □ LIGHT INTENSITY ABOVE 100 FOOT-CANDLES

PERCENT OF TIME IN FIELD FIGURE G LIGHT INTENSITY BELOW 100 FOOT-CANDLES

100 PERCENT <£

83 7.

65 7.

0 PERCENT

LEAST & SEMI-PALMATED PECTORAL ALL SPECIES SANDPIPERS SANDPIPERS I

to O - 2 9 1 -

KEY TO FLY-OFF ROUTES

Route 1952 Humber of Total No. Humber Date Fly-offs of Birds Species

1 Sept. 19 1 4 stilt sandpiper Sept. 5 1 4 pectoral sandpiper

2 Oct. 27 1 18 greater yellowlegs

5 Hov. 2 1 10 dunlin

4 Sept. 12 1 2 peep sandpiper

5 Sept. 10 1 4 stilt sandpiper

6 Sept. 15 1 5 lesser yellowlegs

7 Sept. 12 1 2 peep sandpiper

8 Aug. 24 2 44 peep sandpiper Sept. 9 4 • ^5 stilt, peep sandpiper Sept. 10 1 5 stilt sandpiper Sept. 15. 1 1 stilt sandpiper

9 Aug. 50 5 18 pectoral, peep sandpiper Sept. 1 1 12 peep sandpiper Sept. 2 1 10 peep sandpiper Sept. 18 5 19 peep sandpiper Sept. 15 1 1 stilt sandpiper Oct. 28 1 2 pectoral sandpiper

10 Oct. 20 1 15 pectoral sandpiper

11 Sept. 17 1 6 pectoral sandpiper

12 Sept. 6 1 4 semipalmated sandpiper Sept. 2 8 pectoral sandpiper Sept. 14 1 5 pectoral sandpiper Sept. 15 4 25 pectoral sandp., sesai—pi. Sept. 16 2 5 spotted sandp., seal—pi. Oct. 7 1 2 black-bellied plcrer Oct. 16 1 6 pectoral sandpiper Oct. 20 1 2 pectoral sandpiper

15 Oct. 17 1 9 pectoral sandpiper FIGURE 10 -292-

SHORE BIRD FLY-OFF ROUTES 0*SHAUGHNESSY RESERVOIR

EOOE OF MUOFLAT

ROUTE OF FLY - OFF

BRIDGE t ARROW INDICATES DIRECTION OF FLIGHT LIGHT INTENSITY IN FOOT-CANDLES 20 IO IH ITNIY HNE I CHAMBER IN CHANGES INTENSITY LIGHT IE N IUE O OSRAIN PERIOD OBSERVATION OF MINUTES IN TIME ET9 LIGHTS 9 TEST 5 20 15 IUE II FIGURE 25 30 55 40 -293- 45 LIGHT INTENSITY IN FOOT-CANDLES 20 25 30 IO IH ITNIY HNE I CHAMBER IN CHANGES INTENSITY LIGHT IE N IUE O OBSERVATION OF MINUTES IN TIME 1 1 1 2 2 27 24 21 18 15 12 9 TEST IUE 12 FIGURE 2 LIGHTS 12 PERIOD 30 32 36 -294- LIGHT INTENSITY IN FOOT-CANDLES 120 90 60 30 IL ATR UST N A ON SUNSET AFTER FIELD LIGHT INTENSITY CHANGES CHANGES INTENSITY LIGHT IO IUE 13 FIGURE IE N MINUTES IN TIME 25 0 2 LULS DAY CLOUDLESS IN THE THE IN 0 3 35 40 -295- -2 9 6 - FIGURE 14

SUMMARY OF TEST I zooo TOTAL ACTIVITY OF MALLARDS IN SUCCESSIVE FIVE - MINUTE PERIODS ACCOMPANIED BY DECREASING LIGHT INTENSITY

1600

1500

3 1400

300 >- ® 1200

1100

K lOOO

ui 900

BOO

* 700

X 600

< 500

5 - MINUTE PERIOD

-LIGHT DECREASING- FIGURE 15 SUMMARY OF TEST II

TOTAL ACTIVITY OF MALLARDS in SUCCESSIVE THREE - MINUTE PERIODS TERMINATING A

t w e l v e HOUR PHOTOPERIOD

WITH NO CHANGE IN LIGHT INTENSITY

- 400

MINUTE PERIOD

WITH DECREASING LIGHT INTENSITY

900

sn o2 700

600

5 300

« ZOO

3 -MINUTE PERIOD

-USHT OE-CREASING- FIGURE 16

DAILY TOTALS OF ACTIVITY, TEST II

EACH DAY'S GRAPH REPRESENTS THE ACTIVITY DURING A 3 6 MINUTE PERIOD

WITH NO CHANGE IN LIGHT INTENSITY

USeo 6 Vo _• IO IU E 16 FIGURE

VMHUTt WIOO 1ST. DAY L kJL.l 5TH. DAY 7TH. DAY

WITH DECREASING LIGHT INTENSITY

LIGHT INTENSITY DECREASES FROM LEFT TO RIGHT IN EACH DAY’S GRAPH

fo _ . . CO s»mr u t c Q } 2N0, DAY 4TH. DAY 6TH. DAY 8TH. DAY IOTH. DAY I LIGHT BOX

OBSERVATION WINDOW 17 FIGURE

CONTROL PANEL

DOOR

CUT-AWAY VIEW OF TEST CHAMBER

(LEFT HALF SHOWN) ro toCD -300- APPENDIX 1 GENERAL REFERENCES ON MIGRATION

Borror, D.J. 1948* Analysis of repeat records of banded white-throated sparrows. Ecological Monographs 18:411-430. Drost, R. 1951. Study of bird migration 1938-1950. Proceedings of the Xth. International Ornithological Congress: 216-240. Horstadius, Sven. 1951. Proceedings of the Xth Inter­ national Ornithological Congress. Uppsala 531 pp. Kalela, Olavi. 1954. Populationsokologische gesicht- zur entstehung des vogelzuges. Annales Zoologicu SocietaliS Zoologicae Botanicae Fennicae ’'Vanamo.’1 16(4); 1-30. Lincoln, F.C. 1950. Migration of birds. Circular 16, Fish and Wildlife Service, United States Department of the Interior. Washington, D.C. 102 pp. Mi ski. men, M.A. 1952. The influence of social and physical factors on autumn bird migration. Unpublished Dissertation. Ohio State University. Mi ski men, M.A. 1955. Meteorological and social factors in Autumnal Migration of Ducks. Condor 57(3);179-184. Moreau, R.E. 1950. The migration system in perspective. Proceedings of the Xth International Ornithological Congre s s: 245-248. Phillips, A.R. 1951. Complexities of migration: a review. Wilson Bulletin 63(2):129-136. Rowan, W. 1933. Fifty years of bird migration. Fifty years progress in American Ornithology 1883-1933. Lancaster, Pennsylvania: 51-63. Schuz, E. 1952. Vom vogelzug. Verlog Dr. Paul Schops, Frankfurt am Main. 231 pp. Steinbacher, J. 1951. Vogelzug und Vogelzugforschung, Verlag Waldeman Kramer in Frankfurt am Main. 184 pp. -301- APPENDIX I Continued GENERAL REFERENCES ON MIGRATION

Thompson, A.L. 1949. Bird migration. H. F . and G. Witherby Ltd., London. 183 pp. Thompson, A.L. 1953. The study of the visible migration of birds: an introductory review. Ibis 95(2): 165-180. Van Oordt, G.J. .1943. Vogeltrek. E.J. Brill, Teiden. 145 pp. -302- APPENDIX II REFERENCES ON WEATHER AND BIRD MIGRATION AND NAVIGATION IN BIRD MIGRATION

A. WEATHER Bagg, A.M. 1950. Barometric pressure-patterns and spring bird migration. Wilson Bulletin 62:5-19. Ball, S.C. 1947. Migration of red-breasted nuthatches in Gaspe. Ecological Monographs 17(4):501-533. Ball, S.C. 1952. Fall bird migration on the Gaspe Peninsula. Peabody Museum of Natural History, Yale University, Bulletin 7. 211 pp. Cooke, W.W. 1888. Report on bird migration in the Mississippi Valley in the years 1884 and 1885. United States Department of Agriculture, Division of Economic Ornithology, Bulletin 2. Washington, D.C. 313 pp. Emlen, J.T. Jr. 1952. Flocking behavior in birds. Auk 69(2):160-170. McMillan, N.T. 1938. Birds and the wind. Bird Love 40(6):397-406. Moreau, R.E. 1953. Migration in the Mediterranean area. Ibis 95(2):329-364. Newman, R.J. 1952. Studying nocturnal bird migration by means of the moon. Museum of Zoology, Louisana State University. Baton Rogue, La. 49 pp. Robbins, Chandler S. 1949. Weather and bird migration. The Wood Thrush 4:130-144. Snow, D.W. 1953. Visible migration in the British lies: a review. Ibis 95(2):242-270. Stanford, J.K. 1953. Some impressions of spring migration in Cyrenaica March - May 1952. Ibis 95(2):316- 328. -303- APPENDIX II A. Continued REFERENCES ON WEATHER AND BIRD MIGRATION AND NAVIGATION IN BIRD MIGRATION

Sv&rdson, Gunnar. 1953. Visible migration within Fenno- Scandia. Ibis 95(2):181-211. Williams, G.G. 1950. Weather and spring migration. Auk 67(1):52-65. Williamson, Kenneth. 1952. Migrational drift in Britain in autumn 1951. The Scottish Naturalist 64(1): 1-18. B. NAVIGATION Griffin, D.R. 1952. Bird navigation. Biol. Review of Cambridge. Philosophical Society 24(4):359-389. Kramer, G. and Riese, E. 1952. Die Dressur von Brieftauben auf Kompassrichtung im Wahlkafig. Zeitschrift fur Tierpsychologie 9:245-252. Kramer, G. 1952. Experiments in bird orientation. Ibis 94:265-285. Kramer, G. 1953. Wird die Sonnenhohe bei der Heimfinde- orienterung verwerted? Journal fur Ornithologie 94(3/4):201-219. Matthews, G.V.T. 1951* The experimental investigation of navigation in homing pigeons. Journal of Experimental Biology 28:508-536. Matthews, G.V.T. 1951. The sensory basis of bird nav­ igation. The Journal of the Institute of Nav­ igation 4(3):260-275. Wilkinson, D.H. 1952. The random element in bird nav­ igation. Journal of Experimental Biology 29(4): 532-560. - 3 0 4 - APPENDIX III MIGRATION PHYSIOLOGY

Bissonette, T.H. 1937. Causal factors in migration. Wilson Bulletin 44:254-264. Bullough, W.S. 1945. Endocrinological aspects of bird behavior. Biological Review of the Cambridge philosophical Society 20(3):89-99. Drost, R. 1931. Uber den Einfluss des Lichtes auf den Nogelzug, insbesondere auf die Tageauflruchszeit. Proceedings of the 7th International Ornithological Congress: 340-356. Eyster, M.B. 1954. Quantitative measurement of the in­ fluence of photoperiod, temperature and season on the activity of captive songbirds. Ecological Monographs. 24(1):1-28. Farner, D.S. 1950. The annual stimulus for migration. Condor 52(3):104-122. Farner, D.S., Mewaldt, L.R., and King, J.R. 1954. The diurnal activity patterns of caged migratory white-crowned sparrows in late winter and spring. Journal of comparative and physiological psychology 47(2):148-153* Marshall, A.J. 1951. The refractory period of the testes rhythm in birds and its possible bearing on breeding and migration. Wilson Bulletin 63(4): 238-2,61. Merkel, F.W. 1937. Zur Physiologie des Vogelzugtriebes Zoologische Anzeicher 117:297-308. Moreau, R.E. 1931. Equatorial reflections on periodism in birds. Ibis 1(3):553-570. Palmgren, P. 1944. Studien uber die Tagesrhythmik gekafigter Zugvogel. Zeitschrift fur Tierpsychology 6:44-85.. Palmgren, P. 1949. On the diurnal rhythm of activity and rest in birds. Ibis 91:561-574. -305- APPENDIX III Continued MIGRATION PHYSIOLOGY

Rowan, f. 1946. Experiments in bird migration. Trans­ actions of the Royal Society of Canada, Section 5; 40:123-135. Siebert H.C. 1949. Differences between migrant and non­ migrant birds in food and water intake at various temperatures and photoperiods. Auk 66(2):128- 153. Wagner, H.O. and Schildmacher, H. 1937. Der Einfluss von Aussenfaktoran auf den Tagearhythmus. Vogelzug 8:47-54. Wolf son A. 1945. The role of the pituitary, fat deposition, and body weight in bird migration. Condor 42(2):93-99. Wolf son A. 1954. Production of repeated gonadal, fat, and molt cycles within one year in the junco, and white-crowned sparrow by manipulation of day length. Journal of Experimental Zoology 125(2):353-376. -306- APPENDIX IV

KEY TO WEATHER SYMBOLS

^ — -Wind speed (see below)

Wind direction (wind blows ( Degree of overcast toward circle)

Air Temperature in degrees Fahrenheit DEGREE OF OVERCAST (^) No clouds a 60% overcast

10% overcast 70% overcast

20-30% overcast O 80% overcast

40% overcast 90-100% overcast

( 3 50% overcast ( ^ ) sky obscured by fog, smoke

WIND^ SPEEDS IN ^ FEET PER MINUTE 'C ^ 88-351 352-703 704-1143 1144-1678 1679-2112

no wind -307- APPENDIIC V

scientific h a n d s of b i r d s MDir'i cited in t h -,-rp

great blue heron. . . .Ardea herodias Linne

Canada goose...... Branta canadensis (Linne)

mnscory duck...... Anas meschata Linne

mallard and pekin duck .Anas o 1 a t y r hy r. c h o s Linne

black duck...... Anas rupripes Brewster

redhead...... Aythya americana (Eyton) ring-necked duck. . . .Ayth~~a collaris (Donovan)

canvas-back ...... Aythya valisineria (WIIson) lesser scaup duck . . .Aythya affinis (Eyton)

American golden-eye . .Buceoiiala clangula ameri­

cana (Bonaparte) old souaw ...... Clangula hyemails (Linne) white-winged scoter , .Melanitta fusca (Linne) hooded merganser. . . .Loohodwtes cucullatus (Linne)

American merganser. . .Mergus merganser ameri-

c anus Cu3s in red-breasted merganser. . . . .Mergus serrator Linne red-tailed hawk...... Buteo Jamaicansis boreal! s

(Gir.elin) semioalmated olover ...... Charadrlus hiatlcula semi-

palnatus Bcnap an t e killdeer. . • ,Charadrius vociferus Linne golden plover .Charadrius dominiea P.L.3.

Muller -30&- APrSLDIX V Continued bl-ck-bellied plover...... Charadr Ius s-uatarola

< , 1Linne) ruddy turns tone...... Aren aria int ernr es

nor inelln. (Linne) snipe...... Capella gallinayo (Linne)

'Gilson's s n i p e ...... Capella deli cat a. (Orel)- uniancl plover...... Bartrarnia lonylcauda

( Bechstein) spotted sandpiper Actitis macularia (Lirne) greater yellow-legs ...... TrInga me1anoloucus

( Ariel in) lesser v-ellov.'-legs ...... TrInga flavipes (G-melin) knot...... Calldris canutus rufua

(Xilson) dooritcher...... L inno dr omu s griseus (A me 1 ir ) stint...... C ali dr1s temmlnckii (Leisler) little stint...... Calidria minuta (Leisler) pectoral sandpiper ...... GalIdris melanotos

(Vieillct) v/hit e-rurnped sandpiper .... .C alldr Is fuscicollis

(Vieillot) bairds sandpiper ...... Calidrir, balrdil (Goues) least sandpiper...... Cali dr is nlnutilla

(Vieillot) - 30 9 - APFELDIX V Continued

stilt sandpiper...... Calldris hiruntmns (Bonaparte)

seripalmatod sandpiper ...... Calldris rnslllus (Linne)

'•vestern sandpiper • ...... Calldris maun (Cabonis j

3 an Berlins;...... Croce this ale a ( Pallas )

buff-breasted sandpiper .... Tryng j. tu o s nbrn f 1 s c o 111 s

(Vieillot)

ruff...... Philomachus pugnax (Linne

avocet, ...... Recurvirostra atnericana

(Gxnelin)

l/ilson’s phalarope ...... Steganopua tricolor

Vieillot

northern phalarope* ...... Lobipes lobatus (Linne)

European swallow...... Hirundo rustica Linne

song thrush...... Turdus ericetorum Turton

redwing (red t h r u s h ) ...... Turdus irrusicus Linne

blackbird...... Turdus xnerula Linne

English robin...... Erlthacus rubecula (Linne)

chiffchaff...... Phvlloscopus■ - -- . ■collybita — ,i ...... (Vieillot)

r s t a r l i n g ...... S t u m is vulgaris (Linne)

slate-colored junco ...... Junco hyemails (Linne) w"• ite-crowned sparrow ..... Zonotrichia leucophrys

(Forster) white-throated sparrow. .... Zonotrichia albicollis

(Gaelin) - 310- LITERATURE CITED

Bagg, A.M., Gunn, W.W.H., Miller D.S., Nichols, J.T., Smith, W. , and Wolfarth. 1950. Barometric pressure patterns and spring bird migration. Wilson Bulletin 62(1):5-19. Ball, S.C. 1952. Fall bird migration on the Gaspe Peninsula. Peabody Museum of Natural History, Yale University, Bulletin 7. 211 pp. Barott, H.G., and Pringle, B.M. 1946. Energy and gaseous metabolism of the chicken from hatch to maturity as affected by temperature. Journal of Nutrition 31:35. Bennett, H.R. 1952. Fall migration of birds at Chicago. Wilson Bulletin 64(4):197-220 Blake, C.H. 1953. Turnover ratios. Bird-banding 24(1): 7-10. Borror, D.J. 1948. Analysis of repeat records of banded white-throated sparrows. Ecological Monographs. 18:411-430. Borror, D.J. 1950. A check list of the birds of Ohio with the migration dates of the birds of Central Ohio. Ohio Journal of Science 50:1-32. Brackbill, Hervey. 1952. Light intensity and waterfowl flight; preflight activities. Wilson Bulletin 64(4):242-244. Breckenridge, W.J. 1953. Night rafting of American golden-eyes on the Mississippi River. Auk 70(2): 201-204. Crissey, Walter E. 1955. The use of banding data in determining waterfowl migration and distribution. Journal of Wildlife Management. 19(l):75-84. Devlin, J.M. Effects of weather on nocturnal migration as seen from one observation point at Philadelphia. Wilson Bulletin 66(2):93-101. LITERATURE CITED Continued

Elder, W.H. 1946. Implications of a goose concentration. Transactions of the eleventh North American Wildlife Conference. Emlen, J.T. Jr. 1952. Flocking behavior in birds. Auk 69(2):160-170. Eyster, M.B. 1954. Quantitative measurement of the in­ fluence of photoperiod, temperature and season on the activity of captive songbirds. Ecological Monographs 24(1):1-28. Farner, D.S. 1950. The annual stimulus for migration. The Condor 52(3):104-122. Farner, D.S. 1952. A review of Lowery, G.H. Jr. a quantitative study of the nocturnal migration of birds. 1951. University of Kansas publications of the Museum of Natural History 3(2):361-472. Bird-banding 23(1):43-44. Farner, D.S. , Mewaldt, L.R., and King, J.R. 1954. The diurnal activity patterns of caged migratory white-crowned sparrows in late winter and spring. Journal of Comparative physiological Psychology 47(2):148-153. Girard, G.L. 1941. The mallard, its management in western Montana. Journal of Wildlife Management 5(3): 233-259. Hochbaum, H.A. 1944. The canvasback on a prairie marsh. American Wildlife Institute, Washington, D.C. 210 pp. Hylbon, R. 1950. Migration period of same passerines revealed by daily ringing figures at Ottenby. Proceedings of the Xth. International Ornithological Congress:310-316. Imhof, T.A. 1953. Effect of weather on spring bird mi­ gration in northern Alabama. Wilson Bulletin 65(3):184—195. - 311^ LITERATURE CITED Continued

Kalela, Olavi. 1954. PopulationsSkologische gesichts- punkte zur entstehung des vogelzuges. Annales Zoologicu Societalis Zoological Botanical Fennicae Vanamo 16C4):l-30. Kortright, F.H. 1943. The ducks geese and swans of North America. American Wildlife Institute Washington, D.C. 476 pp. Lack, David.1954. The natural regulation of animal numbers. Oxford, at the Clarendon Press. 343 pp. Leherman, D.S. 1953. A critique of Konrad Lorenz*s theory of instinctive behavior. The Quarterly Review of Biology 28(4):337-363. Lincoln, F.C. 1950. Migration of birds. Circular 16, Fish and Wildlife Service, United States Department of the Interior. Washington, D.C. Lowery, G.H. 1945. Trans-Gulf spring migration of birds and the costal heatus. Wilson Bulletin 57(2): 92-121. McClure, H.E. 1954. An unusual migration of birds at Tokyo, Japan. Wilson Bulletin 66(4):259-263. Merkel, F.W. von. 1937. Zur Physiologie des Vogelzugtriebes. Zoologische Anzeicher 117:297- 308. Miskimen, M.A. 1952. The influence of social and physical factors on autumn bird migration. Unpublished Dissertation. The Ohio State University. Moreau, R.E. 1950. The migration system in perspective proceedings of the Xth International Ornithological Congress: 245-248* Moreau, R.E. 1953. Migration in the Mediterranean area. Ibis 95(2):329-364* Nalbandov, A.V. 1953. Endocrine control of physiological functions. Poultry Science 32(1):88-103. -313-

Newman, R.J. 1952. Studying nocturnal bird migration by means of the moon. Museum of Zoology, Louisiana State University. 49pp. Noble, G.K., and Zitrin, A. 1952. Induction of mating behavior in male and female chicks following injections of sex hormones. Endocrinology 30: 327-344.. Palragren, P. 1943. Zur Tagesrhythm der Fenkenvogel* Ornis Fennica 20: 99-103. Palmgren, P. 1944. Studien uber die Tagesrhythm gekafigter Zugvogel. Zeitschrift fur Tierpsychologie 6: 44-85. Palmgren, P. 1949. On the diurnal rhythm of activity and rest in birds. Ibis 91:561-574. Pough, R.H. 1951. Audubon water bird guide. Doubleday and Company, Inc. Garden City, N.Y. 352 pp. Preston, F.W. 1955. Tail winds and migration. Wilson Bulletin 67(1):60-62. Seibert, H.C. 1949. Differences between migrant and non­ migrant birds in food and water intake at various temperatures and photoperiods. Auk 66(2):128- 153. Seibert, H.C. 1951. Light intensity and the roosting flight of herons in New Jersey. Auk 68(1): 63-74. Sheffield, F.D., and Campbell, B.A. 1954. The role of experience in the ’’Spontaneous” activity of hungry rats. Journal of comparative and physiological psychology. 47(2)97-100. Siivonen L. and Palmgren, P. 1936. Ueber die Einwirkung der Temperatursenkung auf die Zugstimmung bei einer gekafigten Singdrossel (Turdus ph. Philomelas Brehm). Ornis Fennica 13:64-67. - 313 -

LITER ATI! R 'ED (Continued,)

Snow, D..V. 1933. Visible migration in the tritish H e s : a review. Ibis 93(2):992-270.

Stanford, J.K. 1993. Some Impressions ck spring migration In Cyrenaica. Larch - Lav 1932. Ibis 99 (2):310- 12 9.

Steinbacher, J. 19.91 * Vogelzur u nd Vc;• e 1 zuf forschr.nr . 29"erlag 'vvaldernar Kramer in Frankfort am Mein. h ~U n .\ po.

Sturkie, Paul 0. 1999.. Physiology. Comstock Publishing Associates. Ithaca, N.Y. 1.23 pp.

Svardson, G. 1993. Visible migration within Fenno-Scandia. Ibis 95(2):101-211.

Tinbergen, N. 1951. The study of instinct. Oxford at the Clarendon press. 228 pp.

Thomson, A.L. 193-9. Eird migration, H.F. and G. Witherby, Ltd., London. 183 PP*

Thompson, A.L. 1953. The study of the visible migration of birds: an introductory review. Ibis 95(2):165- l8 0 .

Trautman, LI. B. 191-0. The birds of Luck eye Lake, Ohio. Museum of Zoology, University of Michigan, Lumber hip. 1.66 pp.

van Oordt, G.J. 191-3. Vogeltrek. E.J. Lrill, Leiden. 1.L5 pp.

Wagner, E.O. 1937. Der Einfluss von Aussenfaktoren auf den Tagesrhythmus. Vogelzug 5:L'7-53-.

Williams, G.G. 193-5* Do birds cross the Gulf of Mexico in spring? Auk 62(1):98-111.

Williamson, K. 1952. Migrational drift in Britain in autumn, The Scottish Naturalist 65(1):1-13.

Wolfson, A . 1953-* Production of repeated gonadal, fat, ar.d white-crowned sparrow by manipulation of day length. Journal of Experimental Zoology. 12512):353-376. \ " rp , r> - r> p ■ . ! —*r

1, .Jeff 3 'incbv-nd, o n born ’r. 1 nshvllle,

Tennes-eo, Kirch ?/>, l(32 o . I roce'.vcd ray eeceh' :"v— ~

schrcl education in nubile s c boo Is of Tsnnesnei -ZLabam'i

Indiana, Colorado, California, and Flcr Ida. !•'? !;r- cu^r- gradoate training was at the Univeriitv cf Colof! ' ,

and the Ohio State University. I received the “ a-ee

Bachelor of Arts from the* latter institution in- - 'el-9 ,

At the Ohio State University I was employed as a ^ ^clini­ cal assistant, a graduate assistant and .an assis^-'Vnt instructor. After receiving the degree I! as ter oi ohnrts from the Ohio State University in 1950, I held tf*c' posi­ tion cf Research Fellow for three years while cofT-fl_eting the re-uirements for the degree Doctor of Philosr’>h:rv

- 31 5~