This dissertation has been microfilmed exactly as received 68-15,373
RICHARD, David Irving, 1940- THE MOVEMENT PATTERNS OP POPULATIONS OF RED-WINGED BLACKBIRDS, AGELAIUS PHOENICEUS. IN THE WESTERN LAKE tlRIE BASIN.
The Ohio State University, Ph.D„ 1968 Zoology
University Microfilms, Inc., Ann Arbor, Michigan
( £ ) Copyright by
David Irving Richard
1968 THE MOVEMENT PATTERNS OF POPULATIONS
OF RED-WINGED BLACKBIRDS,
AGELAIUS PHOENICEUS, IN THE
WESTERN LAKE ERIE BASIN
DISSERTATION
Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University
By
David Irving Richard, B.Sc., M.Sc.
& & it it it &
The Ohio State University 1968
Approved by ACKNOWLEDGMENTS
I am grateful to my co-advisers, Dr. Mauriee L. Giltz and Dr.
Loren S. Putnam; to Dr. Giltz for providing the idea for this study and his continued guidance throughout, and to Dr. Putnam for his con stant support and encouragement during m y course of studies.
I am indebted to the Ohio Agricultural Research and Development
Center, Wooster, Ohio, for the research assistantship and supplemental operating funds which made this study possible, and to Mr. Richard N.
Smith, 0. S. Fish and Wildlife Service, Columbus, Ohio, for providing the complex of decoy traps used on the Bass Islands.
My thanks go to all who were instrumental in assisting with the observational and banding operations; especially..,to Mr. Joseph Halusky,
Miss Jacqueline Loehr, Dr. M. A. Miskimen, Mrs. Walden E. Richard, Mr.
Robert Schodorf, and Mr. Paul Stonerook, Jr.
I also appreciate the help and ideas contributed by Dr. Melvin I.
Dyer, Dr. M. A. Miskimen, Mr. David E. Schneider, Dr. C. R. Reese, Dr.
Walter Rothenbuhler, and Dr. M. B. Trautman.
Finally, I would like to thank my wife, Susan, for her help with the field observations, for editing and typing this manuscript, and especially for her perseverance during the course of my graduate studies. VITA
October 26, 1940 Born - Fremont, Ohio
June, 1962 . . . B.Sc., Capital University, Columbus, Ohio
1962-1966 . . . Graduate Teaching Assistant, Department of Zoology and Entomology, The Ohio State Uni versity, Columbus, Ohio
March, 1965 . . M.Sc., The Ohio State University, Columbus, Ohio
1966-1968 . . . Research Associate B, Ohio Agricultural Re search and Development Center, Wooster, Ohio
FIELDS OF STUDY
Studies in the Biology, Behavior, and Ecology of Birds. Professors Loren S. Putnam and Maurice L. Giltz
Studies in Animal Behavior. Professors Loren S. Putnam and Walter Rothenbuhler
Studies in Animal Ecology. Associate Professor David H. Stansbery CONTENTS
Page
Acknowledgments...... ii
V i t a ...... iii
Fields of S t u d y ...... iii
Tables ...... vi
Illustrations...... vii
Introduction ...... 1
Materials and Methods ...... 8
R e s u l t s ...... 12
General Flight Behavior ...... 12
Roosting Observations ...... 16
Breeding Observations ...... 19
Feeding Flock Observations ...... 20
Catawba Flights: Spring 1966 ...... 26
General Flight Summary ...... 26
Sex-Age Studies ...... 27
Catawba Flights: Summer 1966 ...... 28
General Flight Summary ...... 28
Sex-Age Studies ...... 29
Catawba Flights; Fall 1966 ...... 30
General Flight Summary ...... 30
Sex-Age Studies ...... 31
iv CONTENTS (continued)
Page
Catawba Flights: Spring 1967 ...... 32
General Flight Summary ...... 32
Sex-Age Studies ...... 34
Catawba Flights: Summer 1967 ...... 35
General Flight Summary ...... 35
Sex-Age Studies ...... 36
Catawba Flights: Fall 1967 ...... 37
General Flight Summary ... 37
Sex-Age Studies ...... 38
Supplementary Flight Observations ...... 38
Island Banding Program: 1966 . . . 40
Island Banding Program; 1967 ...... 41
D i s c u s s i o n ...... 42
Trans-Lake Flyways ...... l42
Breeding Activities ...... 49
Feeding Flock Behavior ...... 54
Roosting Behavior ...... 56
Spring Movements ...... 57
Reverse Migration ...... 64
Summer Movements ...... 69
Fall Movements...... 79
Summary and Conclusions...... 87
A p p e n d i x ...... 90
Literature C i t e d ...... 116
v TABLES
Table Page
1. Morning and Evening Flight Totals - 1966...... 91
2. Morning and Evening Flight Totals - 1967...... 96
3. Banding Program: Resident Females - 1966 and 1967 . . 101
4. Banding Program: Resident Males - 1966 and 1967 . . . 102
5. Banding Program: Summer and Fall Transients - 1966 and 1967 ...... 104
6. Banding Program: Major Repeating Groups...... 105
7. Banding Program: Related Band Recoveries ...... 107
vi ILLUSTRATIONS
Map Page
I. The Western Lake Erie Basin (with trans-lake flyways)...... 109
II. The Catawba Island Area (with local roosts and flyways) ...... 110
Graph
I. Spring Flights at Catawba - 19S6 and 1967 Ill
II. Summer Flights at Catawba - 1966 and 1967 112
III. Fall Flights at Catawba - 1966 and 1967 ...... 113
IV. Mean Daily Red-winged Blackbirds Banded - 1966 .... 114
V. Mean Daily Red-winged Blackbirds Banded - Spring 1967 115
VI. Mean Daily Red-winged Blackbirds Banded - Summer 1967 116
VII. Mean Daily Red-winged Blackbirds Banded - Fall 1967 117
vii INTRODUCTION
The movements of birds have been observed, studied, and "explained" by man for thousands of years. Nevertheless, our basic understanding of this common phenomenon remains highly elusive. A perusal of the litera ture of avian migration leaves the definite impression that bird move ments are highly complex and adaptable, and that even local populations of individual species often differ considerably from one another in their particular migratory behavior. "There is not a 'single,1 there are
'many' migrations, whose circumstances, infinite in variety, change from species to species, region to region, or from one set of conditions to another" (Dorst, 1962:xvi).
This study involves the migration of a single avian species within a particular geographic area. It was undertaken in an attempt to dis cover the gross movement patterns of populations of Red-winged Black birds , Agelaius phoeniceus, in the western Lake Erie Basin region of
Ohio. It was carried out primarily as a behavioral study of the Red winged Blackbirds in this area, with an emphasis on the build-up, compo sition, and fluctuation of the local populations throughout the year.
Although "Red-winged Blackbird" is the accepted common name of this species (American Ornithologists' Union, 1957), it is often referred to as the "Redwing" (Allen, 1914-; Nero, 1956; Bent, 1965). The shorter name appears occasionally in this paper, and should not be confused with that of the European Redwings, Turdus musicus and Turdus iliacus. 1 The Red-winged Blackbird is a diurnal migrant which often follows major topographical features in the landscape in its flights (Meanley and Webb, 1961). Such features are often called "leading lines"
(Mueller and Berger, 1967; Matthews, 1955), and within the study area they consisted chiefly of shorelines and islands. This type of flight phenomenon has been observed in many species of diurnal migrants, and has been called "coasting" (Lack, 1963:478), a term which will be used in this paper.
"The western end of Lake Erie, lying athwart much of the broad route from the Mississippi and Ohio Valleys to central and eastern
Canada, becomes a point of concentration for many migrants" (Gunn,
1951:102). The marshes bordering this south shore of western Lake
Erie from Sandusky to Toledo, Ohio, form the major roost concentra tion areas for Red-winged Blackbirds in the state. Extending five miles northward from the southern shore, just east of Port Clinton,
Ohio, is the wooded, limestone peninsula of Catawba Island (Map I).
Due north, midway across the lake, lie the Bass Islands, part of the western Lake Erie archipelago. The tip of Catawba, which is the em barkation point for most of the northbound trans-Lake Erie flights of
Red-winged Blackbirds in the vicinity, served as the major observa tion site in this study.
The Red-winged Blackbird has been present in Ohio for many years.
Wheaton (1860) reported this species in the state over a hundred years ago. Catawba residents recall that these birds were present in great numbers in the area marshes more than fifty years ago,.when large ex panses of wild rice drew them to feeding areas along the "Harbors"
(West Harbor, Middle Harbor, and East Harbor; see Map II).
The Red-winged Blackbird is traditionally a marsh-nesting bird.
Dawson (1903:19) described the Red-winged Blackbird in Ohio as "a common summer resident throughout the state wherever cat-tail swamps or their equivalent are to be found." Allen (1914) suggests that the
Red-winged Blackbird is not specifically adapted to marsh life, but is merely a highly adaptable bird which may have been pushed from an earlier upland environment like that of the Bobolink, Dolichonyx oryzivorus. In the Catawba Island region today, the Red-winged
Blackbird commonly feeds in the uplands during most of the year, but nests and roosts chiefly in emergent vegetation, primarily cattails,
Typha spp., in the remaining area marshes.
In 1903, Dawson stated that Ohio Red-winged Blackbirds ..were
"markedly decreasing in numbers because of the drainage of the swamps"
(1903:19). Trautman (1940:385), working at Buckeye Lake, in central
Ohio, suggested that "with further drainage and more intensive use of land, which.now seems imminent, a decided decrease in nesting numbers may occur." However, over fifty years ago, Jones (1903:131) noted that "in some regions (of Ohio) where its natural nesting places of rushes and catrtails have disappeared on account of drainage, it has gone into the clover fields and meadows. In others it has taken to the brush." Trautman (1940) and Allen (1914) also reported that some
Red-winged Blackbirds were nesting in moist upland meadow areas.
In most of Ohio today, where the scattered original marsh areas have been drained and filled in recent years, the Red-winged Blackbird commonly nests in upland clover and alfalfa fields in considerably greater numbers per unit area than in the remaining Ohio marshlands
(Giltz, 1967). It is in these upland nesting habitats that most of the Ohio Red-winged Blackbirds originate. Nests in Ohio upland mea dow areas may produce as many as ten million young Red-winged Black birds each year (Smith, 1967).
Dyer (1964) suggests that some Red-winged Blackbirds may have adapted to upland nesting areas from original post-glacial wetland habitats in northern North America during a subsequent drying period, while marsh-nesting birds retreated to the south. Such an early dif ferentiation due to geographic isolation, he notes, could have produced two sympatric types present today, as marsh-nesting birds later rein vaded northern areas. Dyer (1964) found no genetic interchange between upland and marsh breeding Red-winged Blackbirds at Sand Lake, S. D.
If such a differentiation exists, it may be more obvious today due to changing patterns of land use and modern agricultural practices.
Most of the previous studies of trans-Lake Erie avian flights have been carried out on the north shore of the lake. Across the lake islands, forty miles northeast of Catawba, lies Point Pelee, Ontario: a low, marshy, sand spit which extends approximately ten miles south ward from the Canadian shore. This peninsula comprises the north-shore counterpart of Catawba Point on the south (see Map I). Most
of Point Pelee is part of Canada's Point Pelee National Park. It is a
longer and less-developed peninsula than is Catawba, and the larger, more obvious trans-lake flights which begin there have been more readily evident to area ornithologists than have those on the south
shore.
Tavernor and Swales (1907:14-4) reported the Red-winged Blackbird at Point Pelee in 1905 as "a common breeder on the marshes. It was
still common October 29." They observed regular large southward flights of Red-winged Blackbirds from Point Pelee each morning "from sunrise to about eight o'clock...from the first of September on" (1907:46).
N. A. Wood (1910) reported that large flocks of blackbirds, mostly
Red-winged, flew southward down Point Pelee early in the morning daily during early October of 1909. In the fall of 1910, Lynds Jones (1912:
100) observed Red-winged Blackbirds flying south from Pelee Island
"in the morning and at night, not in the middle of the day." Jones carried out a survey of the lake islands and found the species com mon on most of them during the summer months from 1901 to 1910.
The spring migration in the Pelee region has received considera ble attention. On the morning of May 12, 1937, H. F. Lewis (1939) reported several adult male Red-winged Blackbirds flying southward across Lake Erie. These were observed along with large numbers of other small passerines flying south from Fishing Point on the south west corner of Pelee Island into a headwind, a phenomenon which Lewis described as cursus retroversus, or "reverse migration." W. W. H. Gunn (1948) notes that the migration waves arriving from
the south in the spring tend to concentrate on Point Pelee and Pelee
Island, and that the peculiar southward movement of small birds,
chiefly when the wind is from the south, is known to be a common pheno menon. Gunn further states (1951) that, in general, the numerical in tensity of the spring southward flights in the Pelee region is always relatively higher than that of the northward flights.
Pettingill (1964) states that the massing of small birds on Point
Pelee during the spring migration is contingent on the weather, and that the largest numbers appear just after a cold front passes through. He observes that the maximum numbers of Red-winged Black birds appear on the point in late March and early April.
The only published study of migration on the south shore of western Lake Erie was carried out in 1905 and 1906 by Jones (1909;
1910). He described a major south flyway across the lake as extend ing southwest from Point Pelee to the east shore of Pelee Island, southward across Middle Island and Kelleys Island, to the Marblehead
Peninsula on the Ohio shore, southeast of Catawba Point (see Map I).
On occasion, he also observed birds heading southwest from Pelee
Island toward the Bass Islands (1909).
Jones' mainland study area was the small peninsula of Cedar
Point, located northeast of Sandusky, Ohio, and south of Marblehead at the mouth of Sandusky Bay (Map II). No birds were observed ar riving from the north at Cedar Point or as far east as Huron, Ohio, nor was Jones able to report any blackbird flocks "make as though in tending to cross the lake in the northward migration" (1910:33).
Lewis (1939:13) prefaced his remarks on "reverse migration" at
Point Pelee with the following statement. "Thirty-five miles east of the western end of Lake Erie, a series of islands, including Pelee
Island, Kelley Island, Middle Island, and the Bass Islands, together with points jutting out. from the mainland, both north and south, pro vides a natural route for those migrating land birds that have occa sion to cross the lake in this vicinity." Funneling northward from the Sandusky and Huron River Valleys on the south, large numbers of
Red-winged Blackbirds commonly cross Lake Erie to the north from the tip of Catawba Point throughout the season, continuing on northward across the Bass Islands. Although most southbound trans-lake flights in the area seem to originate from Point Pelee and follow the more easterly islands south to Marblehead, some numbers of Red-winged Black bird flights do come south across the Bass Islands to Catawba Point.
Along this "natural funnel" the resultant high concentrations of birds become readily conspicuous, a situation which proves especially suit able for the close observation of local avian movements throughout the year.
This paper presents the daily flight observations at Catawba, the results of an island banding program, and supplementary general field data for the 1966 and 1967 seasons, with a discussion of the gross movement patterns and behavior of Red-winged Blackbirds in the western Lake Erie region indicated by these methods. MATERIALS AND METHODS
A series of daily sight observations on the early-morning and
evening trans-Lake Erie flights of Red-winged Blackbirds was carried out on 198 days from February 20, 1966, through November 26, 1966, and
on 201 days from February 13, 1967, through December 10, 1967, at
Catawba Island, Ottawa County, Ohio (Map II). At this point (latitude
41°35' N, longitude 82°50' W) large numbers of Red-winged Blackbirds
commonly began the thirty-mile lake crossing to the north and to a lesser extent arrived from the north during the season. In addition to the trans-lake flights, some instances of mainland-island move ments were involved in the Catawba flights. These were minimal and will be discussed as they apply.
Flight observations were made with the aid of a 7 x 35 power field binocular from a vantage point at the tip of the Catawba penin sula or from a small boat just north of the tip. Numbers of birds, direction of flight, estimated altitude, approximate flock composi tion, and times of flights were recorded along with general local weather data. Numbers in flocks too large to permit individual
counts were estimated by counting the number of birds in one sector of the flock and "blocking out" the remainder into similar sectors, a 14— foot aluminum boat was occasionally used to follow large flights for short distances across the lake. Concomitant observations by observers in the Bass Islands, three to ten miles north of Catawba
Point, were correlated via use of portable Citizen Band radio trans ceivers. Supplementary flight observations were made on the Canadian shore of Lake Erie, opposite Catawba Island, at Point Pelee and Col chester, Ontario, on April 7, July 22 and 23, 1966, and May 2, 3, July 5,
6, 20, 21, August 9, 10, and October 13 and 14, 1967, and on the
Marblehead Peninsula which extends east from the base of ~Catawba Island and lies south of the more eastern lake islands flyway.
A program of trapping and banding Red-winged Blackbirds was car ried out on South and North Bass Islands. Decoy-traps used were as devised by Linehan (1964) of the U. S. Fish and Wildlife Service, and developed by Giltz (1962) at The Ohio State University. The three traps operated on North Bass Island, 10 miles north of Catawba, were
25 feet by 50 feet by 7 feet, and the trap on South Bass Island, locat ed halfway between North Bass Island and Catawba, measured 50 feet by
100 feet by 7 feet. These were constructed of nylon netting, chicken wire, and steel posts. Down the center of the top of each trap was a four-foot belt of two- by four-inch wire mesh through which the birds could drop into the trap but could not fly out. These traps were baited with a supply of cracked corn and water, and eight to fifteen
Red-winged Blackbirds were left inside as decoys each time they were operated. Every one to three days, trapped birds were funneled into two-foot-square holding cages, banded, and released. 10
Each bird trapped was leg-banded with a serially-numbered alumi
num ring (U. S. Fish and Wildlife Service; #lA-females, #2-males), and
the age of the banded bird was recorded. During heavy flight periods,
four- by one-half-inch strips of colored Facilon plastic material were
fastened to the unbanded leg of the bird by a brass staple. The move
ments of these color-flagged birds in the area were readily evident in
local field observations.
The aging of birds within this study was restricted to Red-winged
Blackbird males. It was not possible to age females in flight, and the determination of age among trapped females was not always readily
obvious and proved difficult to carry out with the numbers of people
assisting with the banding program. Since the juvenile males do not
develop the adult plumage until the post-nuptial molt of the second year, they are easily aged. Males were considered as juveniles
during the remainder of the first season following fledging, and as
first-year males the following spring. On July 1, with the fledging
of the current year's juveniles well underway, first-year males were termed adults.
Trapped Red-winged Blackbirds which had already been banded
either at the same trap or elsewhere were recorded as "recoveries."
Recovered birds represented 26.9% of the males and 11.0% of the fe males in the total banded population. Females comprised only 29.9% of all Red-winged Blackbirds trapped, and generally showed less than
half the tendency to "repeat" in traps shown by the males. Any bird which was repeatedly recovered within one to six day periods was 11 considered present in the area during the total recovery period. Birds present over two weeks in the area were termed area "residents" during the recovery period, while birds present less than seven days were termed "transients." Any banded bird absent from all area traps for a period of 30 or more days between periods of recoveries was consi dered absent from the area during the interim. The daily numbers of male and female Red-winged Blackbirds trapped in the lake islands during the 1966 and 1967 seasons were considered to reflect the size and composition of the area populations (see Nunnelley, 1964; Burtt and Giltz, 1967), indicating the changing status of transient and resident populations in the islands throughout the year. In a spe cies such as the Red-winged Blackbird, which typically exhibits a large amount of social interaction, the recoveries and totals trapped represent the expected trends of much larger numbers of birds.
The Bass Island traps were operated from July and August through
December 12, 1966, and from April 1 through November 30, 1967, during which time 14,643 Red-winged Blackbirds were banded and released. The traps were also operated for recovery data from March 29 through
April 29, 1968.
In addition to the flight observations and banding programs, general field records of Red-winged Blackbird activities in the western Lake Erie area were kept from mid-February through November of
1966 and 1967. RESULTS
The Catawba flight observations and the Bass Island banding pro
gram, the two primary facets of this study, are presented here with references to the tabular and graphical compilations of the data inclu ded in the appendix. The associated general field notes, including the supplementary flight observations, are presented in a concise, summa rized form, chiefly as an adjunct to the local movement patterns indi cated by the primary methods, providing a basis for relating these move ments to the changing patterns of Red-winged Blackbird activities locally throughout the season.
General Flight Behavior
During the observation period, groups of Red-winged Blackbirds com monly flew directly from local roosting sites each morning, within a one- to two-hour period just after sunrise, northward along both shores of the Catawba peninsula to the tip. Altitude of these flights was es timated to average 100 to 200 feet, and flight speed was estimated at
25 to 35 m.p.h. Morning flights at Catawba Point usually began at light intensities of 100-120 f.c. and increased greatly as intensities of 200-300 f.c. and above were reached.
At the northern tip of Catawba, the flocks typically began an up ward circling or spiralling flight pattern with a pronounced gain in
12 13 altitude of an estimated several hundred to a thousand feet or more be fore continuing across the water. This spiralling to higher altitudes was also shown by Red-winged Blackbirds crossing the two-mile stretch of
Sandusky Bay, south of Catawba (Map II). On reaching land again, flight altitudes usually dropped to below several hundred feet.
With heavy following winds, the Red-winged Blackbirds often flew somewhat higher than usual over land, and upon reaching the tip of Ca tawba they typically flew straight north, gaining as usual in altitude over the water, but without the spiralling flight pattern shown under lower wind conditions. With heavy headwinds, circling was commonly shown as the birds reached the point, but flights did not usually gain
f appreciably in altitude over the water, with those continuing on north ward remaining within several hundred feet of the lake's surface. In some cases, Red-winged Blackbirds were observed to fly within a few feet of the water, and sometimes in the troughs below the crests of the waves with heavy cross-winds.
Occasionally flocks would circle for several minutes just north of the tip and then return to Catawba and land or fly back southward along the peninsula. Often, birds would land on Mouse Island, a seven-acre, wooded island lying about 200 yards north of Catawba Point (Map II).
These would either fly up and continue northward with subsequent flights or fly back southward down the peninsula. As the numbers of birds in the flights began to drop off (from one to two hours after sunrise), more hesitancy (circling, flight-reversal, and landing near the point) was shown as the flocks reached the shore. Small island-feeding m populations were present during most of the season, and a few island- roosting birds fed daily at Catawba for extended intervals.
The Catawba flights often involved associated "blackbird" species and other small diurnal migrants. Most often included were Common
Grackles, Quiscalus versicolor; and Starlings, Stumus v. vulgaris; as well as occasional Brown-headed Cowbirds, Molothrus ater; Eastern Meadow- larks, Sturnella magna; Robins, Turdus migratorius; Blue Jays, Cyanocit- ta cristata; Yellow-shafted Flickers, Colaptes auratus; and Mourning
Doves, Zenaidura macroura.
Seasonally, flocks of southbound Red-winged Blackbirds flew across
Catawba Point, usually within one to three hours after sunrise. Alti tudes of these southbound flights varied from a few feet to more than a thousand feet, with those at higher altitudes usually dropping below one to two hundred feet on reaching the mainland. Seventy percent of the
(56) recorded southward flights containing two thousand or more Red winged Blackbirds at Catawba occurred with southerly winds, and the re mainder show winds from the northeast to northwest at an average velo city of 20 m.p.h. (Tables 1 and 2). Trans-lake flights of Red-winged
Blackbirds generally were lower with headwinds and considerably higher with following winds.
Southward flights at Catawba typically continued down the leeward shore of the peninsula to the north shore of Sandusky Bay at altitudes of about 100-200 feet. At this point the birds usually spiralled higher and continued south across the bay at the New York Central Rail road Bridge, or occasionally retained their low-altitude flight level, 15 and funneled southwestward along the north shore of Sandusky Bay (see
Map II), dropping down in area fields to feed. This latter flight pat tern was recorded chiefly during heavy southward migration in late fall.
Since most of the trans-lake northward flights at Catawba origi nated in nearby roosts and feeding sites, local visibility conditions also affected their nature and course. Highest numbers in the north ward flights usually corresponded with days of optimum visibility.
Poor visibility often accompanied relatively higher numbers in the southward flights at Catawba, which commonly showed more compact flock formation. A low cloud ceiling with a clear horizpn usually served to effectively lower the flight altitude over water, and the flights seemed to follow the line of the islands more closely. Heavy fog, rain, or snow conditions often delayed the flights, produced more hesitancy
(circling) and local flight-reversal, and occasionally stopped flights entirely at Catawba Point.
Some Red-winged Blackbird flocks commonly flew northward to the tip of Catawba in the evening, spiralled upward, and continued on across the lake. Some of these evening flocks were observed to fly into the roost site on South Bass Island (see Map II). -The altitude of evening flights dropped sharply as sunset was approached. Often, by the time any eve ning southbound Red-winged Blackbirds reached the Ohio mainland (usually within the half hour before sunset) they were flying within a few feet of the water. Such late evening southward flights commonly followed a course up to a mile east of Catawba Point, directly to Middle Harbor, the nearest large mainland roost (Map II). These late-evening roost 16
flights were estimated to average between 30 and 40 m.p.h. in velocity.
When possible, flights parallel to roadways were paced with an automo
bile speedometer.
Evening flights to roosts from local feeding sites and at Catawba
Point seemed more heavily dependent upon changing light intensity than
did the morning flights from the roosts. When afternoon light inten
sity was lowered earlier than usual by heavy cloud conditions, evening
flights at Catawba often began proportionately earlier. Similar situa
tions at sunrise did not usually delay flight timing significantly ex
cept when accompanied by moderate precipitation.
In general, flock size in the Catawba flights varied from about 10 birds to several hundred throughout the season, except during late May
and early June, and September of 1967, when flights consisted chiefly of
individuals or groups of up to 10 or 15 males. An estimated 85 percent
of the predominantly female flocks recorded in flights at Catawba con
tained at least one Red-winged Blackbird male or grackle, and often
several. Large flights of females were seldom recorded with heavy pre
cipitation conditions or headwinds.
Roosting Observations
The following is a general summary of the field data pertaining to
Red-winged Blackbird roosting activities in the Catawba area during 1966
and 1967.
When the first adult males began to move into and through the
Catawba area in late February, they flew nightly to roosts in areas of 17 cedar woods along the center and west shore, and on Idjuth Bass Island.
Throughout the season, most island residents used the South Bass Island cedar roost. Flocks were also recorded roosting in wooded areas at
Middle Harbor and East Harbor State Park, east of Meadow Brook, and south of Port Clinton (see Map II) early in the spring. These roosts were commonly shared with Starlings and Common Crackles.
By mid-March, some Red-winged Blackbirds were roosting nightly in the remnant cattail stands at Middle Harbor, West Harbor, Meadow Brook, and Port Clinton, as well as numerous marsh areas south of Sandusky Bay
(Map II). These became the major mainland roost areas for the increa sing numbers of males and females during late March and April. During the nesting season, numbers of Red-winged Blackbirds in local roosts decreased. Throughout late May and early June, first-year and adult males were observed flying to roosts nightly. Later in June and through early July, many adult males with territories in the East Harbor and
Middle Harbor marshes and on Mouse Island remained at their territories overnight instead of flying to a roost.
By June 20, a few juveniles and some females were recorded flying to the main cattail roosting sites, and during the next several weeks, additional small roosting areas in cattails and woods were recorded.
During late June and early July these were often communal roosts shared with Starlings and Common Grackles. Numbers of Red-winged Blackbirds
in the roosts increased sharply as more newly-fledged juveniles began to
fly nightly to roosts, and several of these new roosts appeared and
disappeared within several days. 18
By the second week in July, local Red-winged Blackbird roosts were commonly large (5000-20,000) mono-specific aggregates of adult and juvenile males and females. Major roost sites continued to increase in size throughout July and early August. By September, the Middle Harbor,
Fulton Street, and Port Clinton roosts (Map II) had approached an esti mated 10 to 12 times their initial size in early July. These three roosts, together with those at Meadow Brook, South Bass Island, and south of Sandusky Bay, were used regularly until late October. The Mid dle Harbor roost was estimated to contain up to 4-0,000 Red-winged 'Black birds nightly during late July and August.
During late August and early September of 1967, major roosts in the area decreased greatly in size. The Middle Harbor roost, at the base of the Catawba peninsula, contained only small numbers (2000-3000) of juvenile males and females at this time. On August 23, 1967, two new roosts of adult males were recorded in cattail areas at the south end of
West Harbor and south of Sandusky Bay. The West Harbor roost persisted through September. Local field observations of minimal numbers and size of feeding flocks also indicated a sharp decrease in the number of birds present at this time. By late September, numbers of birds in local roosts and feeding flocks had again increased, and the major cattail roost sites remained in use until early November.
By mid-November, most of the marsh roosts were deserted. Red winged Blackbirds in the area had begun roosting nightly in still-leafed deciduous or evergreen woods areas east of Meadow Brook and west of Port 19
Clinton. These late fall roosts were located near the main trans-lake flyways south (Map II).
Breeding Observations
Territorial-associated behavior (sitting up in prominent places, singing with wing-spread display, and chasing other males) was observed in adult males in the Catawba region as early as March 12, 1966, and
March 10, 1967. Females were first recorded within established terri tories in the cattail marshes at East Harbor by March 22, 1966, and
March 31, 1967. Territories contained one to three females. During
April, territorial males were observed feeding singly or in small groups near the territories, usually during the early afternoon hours.
Earliest Red-winged Blackbird nests with clutches of three to four eggs were recorded in the East Harbor marshes on April 28, 1966, and
April 30, 1967. These early nests were located in the thickest stands of the previous year’s growth of cattail. Later nests were usually in new cattail growth, most of which were recorded in the marshes at West
Harbor, Middle Harbor, East Harbor, Port Clinton, Meadow Brook, Catawba, and North Bass Island (see Map II). Six nests were recorded in decidu ous wooded areas at East Harbor State Park (2), Mouse Island (1), Green
Island (1), and central Catawba Island (2). Nests were also reported in red cedar trees, Juniperus virginiana, on South Bass Island and the west shore of Catawba.
During late May, five first-year males were observed to have estab lished territories, chasing other first-year males and one adult male 20 from them. Three of these cases were in upland wooded areas near the lake, one was in a weed field near West Harbor, and the other in cattail marsh at East Harbor. Females were present in one of the wooded terri tories and the marsh territory, although no evidence of actual nesting was recorded.
Juvenile Red-winged Blackbirds were first reported in local roosts about June 20, and in the Catawba Point flights on June 27, 1966, and
June 23, 1967.
Several activity patterns generally associated with territorial be havior were noted among some individuals and groups of males during late
August and September of both 1966 and 1967. Individual males were ob served sitting in prominent places, singing, and often chasing other males. Vocalizing was generally increased in the roost at sunrise and just before sunset, and the large groups of males congregating at mid-day near the feeding areas were often conspicuous by their loud vocalization.
Feeding Flock Observations
The following is a general summary of the field data pertaining to
Red-winged Blackbird feeding flocks collected in the Catawba area during
1966 and 1967.
During late February and early March, feeding flocks consisted of small groups of adult males, often feeding during most of the day with
Starlings and Common Grackles in upland fields of soybean, com, or weed stubble. Throughout March and April, those fields with standing water from spring rains were most often used as feeding areas. 21
By late March, large flocks of 100 to 400 males and some smaller
flocks of females were observed feeding daily in the uplands. By early
April, the flocks of males often contained both adult and first-year
birds, and some of the larger flocks of females were often mixed with males, most of these being first-year birds. Largest feeding flocks at
this time were composed of adult males, occasionally mixed with some
females or first-year males.
Flocks of females became larger through mid-April, as did flocks of
first-year males. By late April, large (500-3000) segregated flocks of males (two-thirds first-year) or females were regularly recorded. By early May, some large flocks of first-year males and some of females were still being recorded.
By the second week in May, only small (20-30) flocks of males (adult and first-year) or females were observed feeding in the uplands. During late April and early May, small groups (2-10) of adult males and an occa sional first-year male were recorded feeding at mid-day; small groups and single first-year males were observed feeding daily in the uplands during May and June. Small daily numbers of island-feeding Red-winged
Blackbirds from mainland roosts were evident throughout the season.
During the nesting season, 100-200 males and a few females flew north daily from Catawba Point to the Bass Islands and returned south each evening.
Migrating Red-winged Blackbirds usually flew directly from the roosts at sunrise for about one to three hours. They then dropped down 22 to feed for the day with local feeding flocks along the flyway. In late
March, resident males had set up territories and flew directly from the roost to their territories at sunrise. During April, territorial birds flew from the territories and fed for decreasing intervals during mid day with the segregated local feeding flocks of non-territorial resi dents and migrating birds. They then left the uplands and flew back to the territories where they remained until sunset.
Non-territorial birds (most first-year males, some females, and lingering migrants) radiated out from the roosts daily and fed in local upland fields during the morning hours in individual flocks or segre gated groups of flocks, as feeding birds "decoyed*' others to the feeding sites. Daily feeding patterns were similar before and after the nesting season. As the day progressed, the groups tended to combine and recom bine in the feeding areas, occasionally breaking up again in moving from field to field. Some flocks flew to feeding areas near the roost sites, while most regularly flew distances up to eight miles from the roosts before settling to feed. Males seemed generally to fly further from the roost to feed than did females. Flight-lines in and out of the larger,
"permanent" roosts remained constant from day to day throughout the sea son. Throughout the day there was a progressive amalgamation of the initially small, scattered feeding flocks, and an increasing directional tendency to move back toward the roost.
During mid-day (from about 1000 until 1400 E.S.T.) the Red-winged
Blackbirds often congregated in the roost if nearby, or in neighboring orchards, woods, or marshes. By mid-afternoon, they usually began flying back and forth to adjoining feeding areas and late in the after
noon the flocks gathered at specific feeding sites along roost flyways
in large mixed aggregates. Largest feeding groups were observed during
late afternoon, along flyways near roosts. About two hours before sun
set, migrating birds began to leave the feeding groups, many of them
flying north across Catawba Point. At about a half hour before sunset, when most northward movements at Catawba ceased, migrants moved with
local birds to a roost near the flyway. Groups of non-migrating Red winged Blackbirds from the feeding aggregates flew to local roosts i shortly before sundown. Late afternoon ’'grouping" sites often con tained birds from two or more different roosts.
In late June and early July, small feeding groups of juveniles and
adult males were recorded in the upland wheat and oats fields. Increa
sing numbers in female feeding flocks were also observed during this time.
During July and early August, juveniles commonly fed with females.
In early July, some adult males were often recorded feeding with the juveniles and females, but by August, adult males were feeding in large
(500-2000) segregated groups. Feeding areas during June and July were chiefly in wheat, oats, weed, and stubble fields in the Catawba area.
By early August, flocks began moving into c o m and bean fields, where they continued to feed through most of September and into early October.
Red-winged Blackbirds were commonly observed in vineyard areas in the
Bass Islands from spring through late fall, although grapes are ripe locally only during September and October. From July through 24
mid-September several hundred adult and juveniles commonly spent most of
the day feeding on Mouse Island and the upper islands, flying south
across Catawba each evening to the roost at Middle Harbor.
During late August and early September, mainland flocks of male Red-
winged Blackbirds were predominantly adult. Increased numbers of juven
ile males were recorded in late September, while larger numbers of
adults were noted in late October and November. Large (1000-3000) segre
gated flocks of both males and females were observed in the Catawba area
during September and October. During late October and November, large mixed flocks of adult males and females were recorded.
Catawba area feeding flocks of Red-winged Blackbirds showed some amount of day-to-day consistency in feeding patterns and sites through out the year.
During the spring of 1967, a flock of about 2500 males (two-thirds adult, one-third first-year), containing a first-year male with a blue flag on the right leg, was observed feeding in a large bean-stubble field east of Route #269 at Bergman’s Market between 1500 and 1700 on
April 6, 9, 10, 11, 18, and 20, and a smaller flock of 100 males (90% first-year) containing one (probably the same) first-year male with a blue flag on the right leg was observed feeding in the same field at
1800 on May 9. No blue flags had been used since September of 1966, and these were the only reports of a marked bird observed in the area during the spring of 1967.
A flock of 1000-2000 females was observed feeding in an oat-stubble jfield near Middle Harbor (Map II) between 1400 and 1800 on April 20, 26, 25
27, May 5, 8, and 9, and a smaller group of about 200 females was re
corded in the same field at 1800 on May 16 and 17, 1967.
During the early summer, a mixed flock of about 1000 (three-fourths
juveniles and females, one-fourth adult males) including a first-year male with a white flag on the left leg was observed feeding between 0900
and 1030 in a field of oats near Middle Harbor on June 29, July 3, 12,
and 25, 1967. Another morning feeding flock of about 500 male Red-winged
Blackbirds (two-thirds juvenile) with two juvenile males marked with blue flags was observed in a wheat field near the entrance to East Har bor State Park at 1050, 0935, and 0815, on July 25, 26, and 27, 1967, respectively.
On seven-acre Mouse Island, some 200 yards north of Catawba Point, a mixed flock of 300 males and females, with two juvenile males marked with a yellow and a blue flag, was observed feeding between 0600 and
0730 on August 15, 20, and 29, and between 1600 and 1800 on August 8,
24, and 29, 1967. In 1966, a similar mixed flock of about 200, inclu ding a marked female and juvenile male, was recorded feeding on Mouse
Island between 0800 and 0900 on September 9 and 21, and between 1600 and
1700 on September 8, 10, and 11.
A flock of about 1500 females, two with blue flags, with a few juvenile males was observed feeding in a bean field just east of Route
#357 near Cheese Haven on September 6, 11, 12, 14, and 26, 1967. A large aggregate flock of about 3000 males and females (two females and two juvenile males marked) was observed in late afternoon, pre-roosting I jI
26
feeding activity in a stubble field northeast of the intersection of
Routes #163 and #2 on September 19 and 22, 1966.
A flock of about 3000 Red-winged Blackbirds (three-fourths females,
one-fourth adult and juvenile males) with a marked juvenile male and
female was observed feeding in a large, newly-plowed field west of
Route #269 opposite East Harbor State Park, at 1630 and 1730 on Octo*-
ber 2 and 3, 1967.
In the flocks and feeding areas described above, all observations
are reported. When time lapses occur within the period of observation,
no data were collected on interim days. Flagged Red-winged Blackbirds
were occasionally recorded in other mainland feeding flocks in the
Catawba area, but only those flocks with appropriate observations indi
cating consistency of location and composition in both flagged indivi
duals and sex-age proportions over a period of several days or more are
cited. Times given are Eastern Standard.
Catawba Flights: Spring 1966
General Flight Summary
Morning and evening flight totals for the period from February 20
through May 31, 1966, are listed in Table 1, and three-day totals for
this period are shown on Graph I. The total number of Red-winged Black
birds observed flying north at Catawba from February 20 through May 31
was 253,000, and the total number of southbound birds for this period
was 126,400.
By late February of 1966, small numbers of adult males began flying north across the lake islands at Catawba. On February 27, 425 adult males flew north at Catawba and 75 flew (back) south. The first week in March showed an increase in the numbers of birds flying at Cataw ba to 500-1500 northward and 200-300 southward daily. From March 7 through May 11, daily northbound flights at Catawba averaged 3600 birds, after which they dropped to a relatively constant 100-200 daily. Peaks in the north flights averaging 7800 birds occurred on March 13 and 22, and April 1, 8, 10, and 14 (see Graph I). The southbound flights increa sed from 500-1500 daily during the second week in March to an average of
2400 daily through May 5. South flight peaks averaging 6900 birds occurred on March 18, 22, and 24, and April 5, 13, 20, and 21. By the second week in May, southward flights had dropped to a minimal 50-100 per day.
Sex-Age Studies
The proportions of recognized sex-age groups involved in the
Catawba Point flights during the spring of 1966 are given in Table 1.
A few females were seen first on March 12 and not again until
March 17. Both of these sightings were in southbound flocks of adult males. The first northbound females were recorded on March 21. During the last week in March, many adult males were observed flying in both north and south directions, while numbers of females in the northward flights increased progressively.
By the first week in April, approximately 70 percent of the north bound Red-winged Blackbirds were females while the southbound flights 28 were still predominantly adult males. First-year males were initially observed in the Catawba flights with northbound flocks of females begin ning on April 1 and increasing throughout the following two weeks, with an occasional first-year male observed also in the south flights.
The second week in April continued to show many females flying northward daily, with increasing numbers of first-year males. South bound flights continued to be composed primarily of adult males, though some females were observed flying south with adult males from Point
Pelee, Ontario, opposite Catawba, on April 7.
The third week in April showed the numbers of females increasing in both directions. First-year males began to appear more commonly in the southbound flights, although some adult males were still being recorded in both the north and south flights. By the end of the week the north ward flights began to decline while the south flights, now composed primarily of females, showed some increase. Some adult males and females continued to fly both north and south across Catawba Point daily through out early May.
Catawba Flights; Summer 1966
General Flight Summary
Morning and evening flight totals for the period from June 1 through
September 15 are listed in Table 1, and three-day totals for this period are shown on Graph II. The total number of Red-winged Blackbirds ob served flying north at Catawba was 166,100; total southbound was 31,600.
The Catawba flights remained generally steady at 100-200 birds north each morning and 100-200 south each evening from late May until the last week in June when daily north numbers began to show a slow in
crease. By the first week in July there was a sharper increase from
400-500 per morning to 2000 in the northward flights. During the last week in July, flight numbers climbed to 3000 per morning, and during the first half of August, daily morning flights north from Catawba averaged
4100 birds. Peaks of 6000-7000 per day were reached on July 31,
August 1, 4, and 6. After August 15, the northward flights dropped steadily down to an average 1000 per day by early September. Evening flights north were quite small and showed little change throughout the summer.
South flights at Catawba from June 1 through September 15 were generally small, averaging only 100-200 birds per day through July 21, with a rise to 500 per day through September 15. South flight peaks of over 1000 birds occurred on July 22 and 31, and August 1, 4, and 24.
Evening flights south averaged 100 daily from June through August 21.
During late August and early September the average number of Red-winged
Blackbirds flying south each evening at Catawba rose to 400.
Sex-Age Studies
The proportions of recognized sex-age groups involved in the Cataw ba Point flights during the summer of 1966 are given in Table 1.
During the first three weeks in June, most of the Red-winged Black birds recorded at Catawba Point were adult or first-year males. Occa sionally females were also observed. On June 27, females and some juveniles began to appear regularly in the north and south flights, both morning and evening, daily. Proportions of females and juveniles gradu ally increased in the morning and evening northward flights throughout
July. The evening south flights during July consisted chiefly of adult males, although increased numbers of females and juveniles flew both north and south in the evenings during the late summer.
Larger numbers of juvenile males were recorded in the northward flights with females and adult males on July 4, and these increased sharply in proportion during the next two weeks. By July 21, daily northbound flights consisted of an estimated 20 percent adult males,
50 percent juveniles, and 30 percent females. Throughout August and early September, northbound flights were predominantly juvenile males and females, with occasional adult males.
Catawba Flights: Fall 1966
General Flight Summary
Morning and evening flight totals for the period from September 16 through November 26, 1966, are listed in Table 1, and three-day totals for this period are shown on Graph III. The total number of Red-winged
Blackbirds observed flying north at Catawba Point was 148,600, and the total number of southbound birds was 82,100.
During late September and early October, morning flights north at
Catawba remained fairly constant at about 200-500 birds daily. South ward flights often contained about the same numbers as the corresponding northward flights. Evening flights north and south remained very small until late October when larger numbers of birds began to be recorded in the southward flights. Both north and south peaks of 2200 and 5000 31
Red-winged Blackbirds were observed on the mornings of October 3 and 7.
On October 12, morning northward flights soared to 16,4-00 birds.
During the remainder of the month, daily northward flights varied
from 1000 to 17,000 Red-winged Blackbirds. Peak numbers averaging
12,400 daily flew north on October 20, 21, 23, 25, and 30. Southward
flights fluctuated between 500 and 4000 daily, with one peak of 7200
birds on October 24.
By late October, both morning and evening southward flights were
showing a steady increase in numbers up to 5000 per day during mid-
November, dropping off completely by early December. North flights
dropped to below 100 birds daily during early November and dropped off
completely by November 20.
Sex-Age Studies
The proportions of recognized sex-age groups involved in the Cataw
ba Point flights during the fall of 1966 are given in Table 1.
During late August and early September, 1966, flocks of juvenile males and females were observed flying north from Catawba Point in the
morning, and some were recorded flying south. Adult males were observed
in the morning south flights during mid- and late-September and on the
first few days of October, this latter time with many females in the
flocks.
Throughout October, large flocks of juvenile males and females,
many of them mixed, commonly flew north from Catawba Point each morning.
Some flocks of similar composition were also observed flying southward 32 on several mornings during early October. The morning northward flights dropped off sharply by early November.
During late October and through most of November, flocks of juven iles mixed with steadily increasing proportions of females and adult males were observed flying southward at Catawba, usually within two to four hours after sunrise, but occasionally in November, heavy flights of both males and females were observed in the late evening only a few minutes before sunset. By late November, only some adult males and a few juvenile males were recorded in the rapidly decreasing Catawba flights.
Catawba Flights; Spring 1967
General Flight Stimmary
Morning and evening flight totals for the period from February 20 through May 31, 1967, are listed in Table 2, and three-day totals for this period are shown on Graph I. The total number of Red-winged Black birds observed flying north at Catawba during this period was 492,000, and the total number of southbound birds was 143,120.
An isolated northward flight was recorded on February 20, 1967, when about 200 adult males flew across the lake from Catawba Point. On the evenings of February 20 and 22, about 10 males were observed flying south at Catawba. No further sightings were recorded until March 3 when
200 Red-winged Blackbirds flew north in the morning and 1300 in the evening. Not until March 7 did the 1967 flights at Catawba begin on a regular basis. 33
Numbers of Red-winged Blackbirds flying north went from 100 birds
on March 7 to 27,000 on March 11, and the beginnings of the spring south
ward flights were observed. South flights at Catawba for the next week
averaged 150-200 Red-winged Blackbirds each morning and evening. The
first heavy northward movement lasted from March 11 through March 15,
with average northbound totals of 19,000 birds per day.
During the next week, the southward flights increased to 1000-1500
Red-winged Blackbirds daily, with highest numbers flying in the evenings.
Northward flights also were higher in the evenings with daily totals
from 1500-5000.
Through the third week in March, a second northward influx was re corded, with peak days on March 23, 24, and 26, when 36,000, 38,000, and
14,000 Red-winged Blackbirds flew north across the lake from Catawba.
During late March, northward flights fluctuated between 5000 and 8000 daily. Southward flights averaged 1000 daily, with a peak on March 27 of
8,400 birds.
April 1 showed a heavy northward flight of 13,000 birds, after which daily north totals dropped to an average of 3500 for the next three weeks with one peak of 10,000 on April 10. South flights were generally small at 500-1500 per day, with heavier flights on April 1, 2, and 14 through 17, of 6000-12,000 daily.
On April 19, the Catawba observations showed the beginning of a third influx of northward flights of 5000-15,000 daily continuing through April 28. After this movement, the northward flights dropped to daily averages of 1000-5000 through mid-May with one peak of 8000 on 34
May 10. A sharp drop in the numbers of northward flying Red-winged
Blackbirds at Catawba to 100-200 birds daily was seen during late May, and a similar drop in the south flights began in late April, with moder ate flights of 2000-3000 birds on April 29 through May 3, and again on
May 5 and 14.
Sex-Age Studies
Proportions of recognized sex-age groups involved in the Catawba
Point flights during the spring of 1967 are given in Table 2.
Most of the flocks flying across Catawba in February and early
March of 1967 contained adult males only. A few females were recorded with larger adult male groups on February 20 and March 10. Not until
March 18 were females recorded in regular flight at Catawba. Propor tions of females increased during the next week, and by March 24, morn ing flocks contained an estimated two-thirds females and one-third adult males flying north.
March southward flights consisted mainly of adult males, but on the evening of April 2, large numbers of females were recorded together with adult males flying south at Catawba. Southward flights were recorded both mornings and evenings throughout April as containing some adult males and increasing numbers of females, as well as first-year males.
Observations at Point Pelee in early May showed many females and some adult males still flying southward across the lake.
During April, many first-year males and some females and adult males were observed flying northward at Catawba. This trend continued 35
through the first half of May with a decrease in numbers of first-year
males, and some adult males and females continuing to fly northward
daily until May 16. During late May, most of the Red-winged Blackbirds
flying at Catawba Point were first-year and adult males, although an
occasional female was also recorded.
Catawba Flights: Summer 1967
General Flight Summary
Morning and evening flight totals for the period from June 1 through
September 15, 1967, are listed in Table 2, and three-day totals for this
period are shown in Graph II. The total number of Red-winged Blackbirds
recorded in northward flight at Catawba during this period was 215,600;
total birds in the southbound.flights was 49,800.
The numbers of Red-winged Blackbirds flying daily at Catawba Point
from late May through early June remained quite low, fluctuating between
50 and 200 birds north each morning and about the same numbers south
each evening. By the last week in June, a well-defined increase in morn
ing northward flights was shown, with totals of 1000-2000, climbing to
2000-7000 birds daily by the second week in July. During the third week
in July, daily northward totals increased to an average 9000, with peaks on July 16..and 17 of 18,000 and 12,000 birds. By the last week in July,
daily northward numbers averaged about 4500.
By early August, the daily numbers had dropped to 3000 birds flying north. Throughout August there was a steady decrease in the north flights
until by early September, they were down to only about 600 birds per day. 36
Numbers in the southbound flights from June through August remained quite low, with an average of 200 Red-winged Blackbirds each morning and about the same numbers each evening. Peak southward flights of 400 and
500 daily occurred during mid-July.
Sex-Age Studies
Proportions of recognized sex-age groups involved in the Catawba
Point flights during the summer of 1967 are given in Table 2.
During early June of 1967, the flights at Catawba Point contained chiefly males, both adult and first-year, flying north each morning and southward each evening. A few females were occasionally noted in the evening southward flights. On the evening of June 22, some juveniles and females were recorded with adult males flying south at Catawba. The following morning, more juveniles were recorded in the northbound flights with adults and first-year males. During late June, increasing numbers of females and first-year males were observed in the Catawba flights, along with some juveniles and adult males.
By the first week in July, numbers of adult males in the morning northward flights from Catawba increased sharply, and more juveniles were recorded in the flights. During the second week of July, sharply increasing numbers of juveniles were recorded with adult males in the north flights. By late July, the numbers of adult males flying had dropped considerably, while the numbers of juvenile males and females continued to increase, still accompanied by some first-year males. 37
Throughout August, the daily morning flights northward from Catawba consisted of about half juvenile males in mixed flocks with females and occasional first-year and adult males. Evening flights during July were made up largely of adult males flying southward, while those during
August were smaller and contained flocks of adult males mixed with some females and juveniles coming south.
Catawba Flights: Fall 1967
General Flight Summary
Morning and evening flight totals for the period from September 16 through December 1, 1967, are listed in Table 2, and three-day totals for this period are shown on Graph III. The total number of Red-winged
Blackbirds recorded in northward flight at Catawba during this period was 38,900; total in the southward flights was 267,600.
During late September of 1967, Red-winged Blackbird flights north ward at Catawba Point dropped off completely. Flights south were ob served to increase during mid-September up to 2000 birds per morning, but those dropped off again by the end of the month.
During the first week in October, numbers flying both north and south rose sharply to a peak of 6200 on October 4-, and then dropped off again. Northbound flights increased again in mid-October, averaging
3000 birds daily, but then dropped to 200 per day by late in the month, and disappeared completely by November. Southward flights also increa sed sharply during mid-October, averaging about 5000 birds daily until early November when they soared to peaks of 9000 and 12,000 on Novem ber 3 and 4, and 30,000 and 16,000 on November 8 and 10. They 38 continued to average about 7000 birds daily until dropping off to several hundred per day by late November. By early December there were no longer any regular flights at Catawba Point.
Most of the heavy flight movements recorded at Catawba during the fall of 1967 occurred in the morning, although during late October and through November, when the southward flights were heaviest, some evening flights from 100 up to 8000 per day southward were commonly observed.
Sex-Age Studies
Proportions of recognized sex-age groups involved in the Catawba
Point flights during the fall of 1967 are given in Table 2.
During late September, adult and juvenile males were recorded in the southward flights at Catawba Point both mornings and evenings.
During early October, increased numbers of females were observed in the morning northbound flights with juveniles and some adult males. By mid-
October, southward flights began to contain larger numbers of females with adult and juvenile males; these increased and continued through mid-November when the proportion of females dropped off sharply. By late November, only small numbers of adult and juvenile males were re corded in flight at Catawba Point.
Supplementary Flight Observations
During the study period, occasional supplementary flight observa tions were made at appropriate sites along the trans-lake flyways.
On April 7, 1966, and May 1, 2, and 3, 1967, observations at the southern tip of Point Pelee, Ontario, (see Map I) showed numbers of females and males flying southwest across the lake toward Pelee Island, both in the morning and evening. These flights were recorded with northwesterly winds at 10-15 m.p.h., and occurred at altitudes estimated at between 500 and 1000 feet except on the evening of May 1, 1967, when southeast winds at 15 m.p.h. were recorded and the flights occurred at altitudes estimated at less than 200 feet. Several low-flying flocks of (10-20) males were recorded arriving from the southwest at Point
Pelee on the morning of May 2, about two hours after sunrise. The April sighting showed primarily males with some females in the flights while most of the May flights contained higher proportions of females.
On July 23, 1966, and July 5, 6, 20, and August 9, and 10, 1967, observations at Point Pelee showed no evidence of Red-winged Blackbird flights.
On July 22 and 23, 1966, and July 21, 1967, mixed flocks of males and females were observed flying northward across the open lake at a point about six miles east of Colchester, Ontario, (see Map I) with light, variable wind conditions.
On October 13 and 14, 1967, heavy mixed flights of Red-winged
Blackbirds were observed flying southwest from Point Pelee toward Pelee
Island at altitudes estimated at less than 200 feet, with southwesterly winds at 12 m.p.h. No northward flights were observed.
During late October of 1966, and late March, April, early May,
October, and November of 1967, regular, southward movements of Red winged Blackbirds from the direction of Kelleys Island were observed arriving at the north shore of the Marblehead Peninsula between HO
Lakeside, Ohio, and the eastern tip (Map II). Smaller, sporadic north ward flights directed toward the west end of Kelleys Island were recorded
at the eastern tip of Marblehead during March and April of 1967. Most flights from further east, moving across the Cedar Point-Bay Point path way (Map II) tended to "coast’1 northwestward along the lake shore to the
Middle Harbor roost and Catawba Point.
Island Banding Program: 1966
Mean daily numbers of Red-winged Blackbird males and females banded in the Bass Islands during 1966 are shown on Graph IV. During the. period from July 2 through August 31, 1966, 1621 males (487 adults; 1134 juven iles) and 747 females were banded in the islands; 463 males (73 adults) and 146 females were recovered. During the period from September 1 through November 31, 1966, 2447 males (659 adults; 1788 juveniles) and
1316 females were banded in the islands; 750 males (92 adults) and 143 females were recovered. Monthly recovery data for 1966 are shown in
Tables 3, 4, and 5, and major repeating groups are shown in Table 6.
Related area recoveries are given in Table 7.
From July 2 through November 31, 1966, 199 male Red-winged Black birds (8 percent adults) were present in the island area and then became absent for a period of 30 or more days before again being recorded in the islands. Eighty-nine percent of these males left the area between
July 8 and September 5, 1966. Ninety percent of these males first re turned to the islands following an absence of over a month between
September 13 and November 19, 1966; 71 out of the 199 (36 percent) re turned first between October 6 and 17, 1966. Island Banding Program: 1967
Mean daily numbers of males and females banded in the Bass Islands during 1967 are shown on Graphs V, VI, and VII. During the period from
April 8 through May 31, 1967, 593 male Red-winged Blackbirds (137 adults
456 first-years) and 321 females were banded in the islands; 14-1 males
(51 adults) and 14 females were recovered. From June 1 through
August 31, 1967, 4788 males (1364 adults) and 1829 females were banded in the islands; 1320 males (208 adults) and 239 females were recovered.
During the period from September 1 through November 30, 1967, 796 males
(159 adults; 637 juveniles) and 167 females were banded; 481 males (57 adults) and 38 females were recovered in the islands. Monthly recovery data for 1967 are shown in Tables 3, 4, and 5, and major repeating groups are shown in Table 6. Table 7 shows related local recoveries.
During the period from June 1 through November 30, 1967, 182 male
Red-winged Blackbirds (6 percent adults) were present in the island area and then became absent for a period of 30 or more days before again being recovered there. Eighty-two percent of these males left the is land area between July 17 and September 5, 1967. Ninety-one percent of these males first returned to the islands following an absence of over a month between September 12 and November 7, 1967; 87 out of the 182
(48 percent) returned first between September 12 and October 6, 1967. DISCUSSION
Trans-Lake Flyways
The flight patterns of Red-winged Blackbirds in the Catawba area
remained fixed along definite flight pathways which were stable within
each season and from year to year (see Map II). The Catawba peninsula
forms the southern end of the major Red-winged Blackbird flyway north
ward across the islands of western Lake Erie. Banding reports indicate
that many of the same birds, both adults and juveniles, use the island
flyways across the lake during both the fall and spring flights annu
ally (Table 6).
Wind direction and velocity, as well as general visibility, (see pp. 13-15) seemed to bring about the most pronounced effects on the nature and course of the trans-lake flights. In general, Red-winged
Blackbird flights over land occurred at altitudes of about 100-200 feet or less, while flights over water often showed considerable gains in altitude (p. 13). Mueller and Berger (1967) note that many land birds typically fly lower over land than over water.
In general, diurnal migrants "coast" more at low than at higher altitudes (Mueller and Berger, 1967; Lack, 1963). If this were the case with Red-winged Blackbirds, most of the northbound flights from
Catawba (spiralling to higher altitudes over the lake) would follow the
islands relatively little after leaving the Ohio Mainland. A due-north
42 43
course from Catawba Point across the lake would bring these flights over
the Bass Islands to the Canadian shore at a point about five to six
miles east of Colchester, Ontario (Map I). Near this point, on July 22
and 23, 1966, and July 21, 1967 (days of light winds during periods of
heavy northward movements at Catawba), continuous mixed flocks of Red
winged Blackbirds arrived from the south across the open lake about an
hour after sunrise (p. 39), dropping into feeding areas along the lake
shore. Birds banded in the Bass Islands were later recovered near this
point on the north shore (Table 7). When northbound Red-winged Black
birds at Catawba Point occasionally met heavy northerly winds they would
(maintain lower flight altitudes and) follow the lake islands more
closely, flying from Catawba and the Bass Islands northeast across Pelee
Island to the west shore of Point Pelee. Northward avian flights ob
served at Point Pelee tend to be less frequent and more erratic in occur
rence than southward flights, and are heaviest with northerly winds
(Gunn, 1951).
Most southbound flights of Red-winged Blackbirds (flying at high
altitudes over the lake, with little "coasting" shown) leave the Cana dian shore at Point Pelee from local roosts (Gunn, 1951), and fly approxi mately due southward across the more easterly lake islands to the
Marblehead Peninsula, east of Catawba Point (Map I). Red-winged Black bird flights south across the open lake have been observed at Pelee
Island, Middle Island, and Kelleys Island during the fall (Jones, 1912) and spring (Lewis, 1939; Gunn, 1951). Flights arriving from the north at Marblehead were also observed by Jones (1912) in October of 1905 and 44
1906, and by myself during both the spring and fall months (see p. 39).
Gunn (1951:77), noting the occasional observations of southbound avian flights from some of "the smaller islands to the southwest" of
Point Pelee as well as across Pelee and Middle Islands toward Marblehead, suggests that the evidence does not point to the existence of a single concentrated flightline across the lake from Point Pelee. Tavernor and
Swales (1907) and Jones (1910) report, however, that no birds were seen crossing the lake except in a line with the islands. Redr-winged Black birds flying south from Point Pelee into southerly winds generally main tain low flight altitudes, and are readily obvious to observers there.
The widely-known "reverse migration" phenomenon each spring in the Pelee region is excellent evidence of this. These low-flying birds follow the islands more closely, bringing many Red-winged Blackbirds southwest across the Bass Islands to Catawba Point. Erratic south-southwestward flights of Red-winged Blackbirds were observed leaving the southwestern tip of South Bass Island during both the spring and fall months of 1966 and 1967; and most of the heavy southward Red-winged Blackbird flights across Catawba Point occurred with southerly winds (p. 14).
The remaining large southward movements of Red-winged Blackbirds at
Catawba Point were recorded with high northwesterly or northeasterly winds (p. 14). With strong cross-winds, Red-winged Blackbirds attempting to make a trans-lake crossing were occasionally observed to "compensate" for wind drift effects by flying north or south at an angle into the wind at low altitudes. Southbound flights across Catawba with heavy cross-winds were probably the result of large numbers of low-altitude, 45
"coasting" birds, or high-altitude flights that had been drifted west to the Bass Island-Catawba area from Point Pelee. Drift effects were prob ably small except when poor visibility obscured the lake islands and shorelines as landmarks, or during high-altitude flights. Lack1s
(1960a) radar studies indicate that migrants commonly correct for wind drift only when flying at relatively low altitudes.
There was generally more correspondence shown between numbers of birds trapped in the islands and the numbers observed in the northward flights at Catawba Point than in the southward flights. The sex-age proportions among trapped birds also agreed more closely with those ob served in the northward flights (Graphs I-VII). This correlation is as expected since most Catawba northbound flights continued directly across the Bass Islands whereas the southbound trans-lake flights which came across Catawba Point often skirted only the southeast shore of the low er Bass Islands during the flight from Pelee (Map I).
Relative visibility in the area also affected flight altitude and, therefore, the degree of "coasting" across the islands. Poor general visibility, low cloud ceilings, and/or small amounts of precipitation were often associated with lower flight altitudes and maximal southward movements across Catawba Point (p. 15). With good visibility across the lake (and no "adverse" wind conditions) higher flight altitudes and minimal southward movements were observed at Catawba.
Because of the large amount of "coasting" flight behavior shown along the southern shore of Lake Erie near Catawba, it is probable that northward moving Red-winged Blackbirds do not cross the western end of the lake except along the island pathways. Flights of Red-winged Black birds were observed during the spring and summer months both in the morning and evening moving westward along the lake shore as far east as
Huron, Ohio. Westward flights along the shoreline were observed to con tinue northwest from Cedar Point, arriving at the southeast point of
Marblehead (Map II), and some flocks were observed to fly directly north toward Kelleys Island (p. HO). However, most of the flocks continued west and north along the "Harbor" shorelines to the tip of' Catawba Point before crossing the lake (Map II). Similar patterns of "coasting" flight would be expected from other peninsular areas such as Long Point and Point Pelee, Ontario.
Catawba Point also received many Red-winged Blackbirds crossing
Sandusky Bay at the New York Central Railroad’ Bridge and from the western end at the mouth of the Sandusky River (Map II). Some of the flights from the Sandusky River Valley (as well as a few from Marblehead follow ing the south shores of East and West Harbors westward to Port Clinton) commonly moved northwest along the lake shore west of Port Clinton during the spring and summer. Large northwestward movements of Red winged Blackbirds observed along the shoreline near the Ottawa Wildlife
Refuge (Map I), together with banding data collected there (Table 7) during the summer months of 1966 and 1967 (Giltz, 1968c), indicate the existence of a similar "coasting" flight pattern around the western end of the lake. Jones (1909) describes a hypothetical migratory pathway northward to Lake Erie along the Scioto-Sandusky River Valleys. Since no recoveries of Red-winged Blackbirds banded in the Columbus area (Burtt and Giltz, 1967) were recorded in the lake islands or south of
Sandusky Bay (Giltz, 1968a; 1968d) during the spring or summer months,
Columbus-banded Red-winged Blackbirds, following the river flyway north
ward to the lake, may traditionally fly west of the island flyways
around the western end of the lake. One Columbus-banded male Red-winged
Blackbird was recorded at the Ottawa Refuge in July of 1966, whereas
birds banded at Columbus (3) and at Ottawa (2) were recovered in the
Bass Islands only during October (Table 7). It is probable that many
Red-winged Blackbirds, "coasting’1 northward around the western end of
Lake Erie during spring and summer, use the island pathway across the
lake during the fall migration.
Of twenty-four early-spring (March and early April) recoveries in
Ohio of Red-winged Blackbirds banded during previous years in the Bass
Islands or south of Sandusky Bay, all but one occurred east of the
Catawba area (east of 83° W long.). Most were reported in the vicinity of the Huron, Vermillion, or Mohican River Valleys (Giltz, 1968a;
1968d). Of fourteen adult Red-winged Blackbirds banded as juveniles in the lake islands or south of Sandusky Bay which were subsequently re covered during the nesting season (late May through June) elsewhere in
Ohio, only one occurred west of the Catawba area (83° W long.), and all were north of 40° N lat. (Giltz, 1968a; 1968d). Immigrating juvenile birds in the Catawba area following the nesting season are apparently from nesting areas other than the vicinity of Sandusky Bay or Columbus
(due south of Catawba) where thousands of Red-winged Blackbirds have been banded during the past six years (Giltz, 1968a; 1968b). Banding recoveries (Giltz, 1968a) during the period of the fall mi gration show an east-southeasterly trend south of the lake from the
Catawba area. "Coasting" southward flights from the more easterly Long
Point, Ontario, may be indicated. In general, a northwesterly trend across Ohio is reflected in the spring and summer movements of Red winged Blackbirds, whereas a reversed (southeasterly) trend is shown during the fall months. This would account for the small interchange of banded birds between Columbus, Ohio, and Catawba, 120 miles due north.
It has been stated that visible avian migration may provide a mis leading conception of migratory flights (Lack, 1963). However, Red winged Blackbirds in the Catawba region flew relatively short distances daily; flights generally lasted less than three hours throughout the season. The northward flights at Catawba occurred at low altitudes over land, and included birds which had "coasted" north to the lake and along the shoreline for some distance from both the east and west to the tip of the peninsular "funnel." Migrants and wanderers usually flew north from Catawba Point for only one or two hours just after sunrise and another one to two hours just before sunset. Both north and south shore observations of morning flights arriving across the open lake showed the flocks dropping down in feeding areas near the lake with local flocks, where they fed for most of the day. Evening flights ar riving across the lake typically joined local flocks moving to roosts near the shore. Most of the Red-winged Blackbirds involved in the
Catawba flights, therefore, originated in local roosts (morning flights) **9 or local feeding areas (evening flights), funneling northward along both shores to the point.
A monitor of the morning and evening trans-Lake Erie flights of Red winged Blackbirds at Catawba Point, should reflect a complete picture of northward flights through and away from the large south-shore roost con centration areas throughout the year. : These observations should also indicate any southward trans-lake movements of Red-winged Blackbirds,
"coasting” southwestward across the islands to Catawba from Point Pelee.
Breeding Activities
Banding data (Tables 6 and 7) show many of the same "resident" Red winged Blackbirds returning to the Catawba area for the nesting season each year. Some marked adult males had set up territories by late
March of 1967 in areas held by them the previous year. Many early- arriving adult males, present in the Catawba area in early March, exhi bited territorial-associated behavior patterns such as sitting in the tops of trees, on fence posts, and telephone lines, giving the terri torial "song-spread" display (Nero, 1956) and chasing other males. Con sidering the large numbers of adult males present in the area at this time, and the fact that much of this early territorial behavior was ob served in areas where no Red-winged Blackbirds were later recorded nesting, a large part of this activity may be attributed to migrating birds. According to Allen (1914), initial adult males arriving at
Ithaca, New York, in the spring of the year, were migrants. Nero
(1956:131) also observed the occurrence of "incipient territorial be havior" on the part of transient male Red-winged Blackbirds arriving in 50 the early spring, although many males present at Catawba by mid- to late-
March were observed to establish and maintain territories as residents
(p. 16). Giltz (personal communication) suggests that territorial be havior may be exhibited by potentially breeding male and female Red winged Blackbirds in the spring as soon as local daily temperatures begin to rise consistently above 32°F. This may be evident in the Lake
Erie region sooner because of conspicuous nesting sites in the remnant cattail stands.
Allen (1914) states that initial females arriving at Ithaca, New
York, marshes in the spring were usually migrants also, although Beer and Tibbitts (1950) noted resident females arriving at Madison, Wiscon sin, marshes prior to the migrant females. Individual females were recorded within defended territories of resident males in marshes near
Catawba as early as March 22, 1966, (p. 19) just after the initial regular appearance of females in the trans-lake flights (p. 27), and two weeks before Allen recorded the arrival of resident females in upper
New York. Nero (1956) states that the pairing bond is formed when the female first enters a male’s territory and usually persists through the breeding season. Some resident females evidently may arrive in the
Catawba area along with the first large influx of females in the spring, although most of these early females are probably migrants.
Wright and Wright (1944) and Nero (1956) state that most first-year males do not develop territories, and thus do not breed. First-year males were observed feeding daily, individually or in small groups, at
Catawba area feeding sites throughout the nesting season (p. 21), indicating that many did not establish and defend territories. Some
evidence of wandering was also noted (Table 6). Territorial-associated
behavior was recorded among five first-year males in the Catawba area,
two of which involved females within an apparently defended territory
(p. 20). Beer and Tibbitts (1950) suggest that first-year males do not
usually establish territories, but may tentatively select the territory
which they will use the following year. Wright and Wright (1944) mention
cases of first-year males flying at intruders much as territorial adults,
and Smith (1943) mentions first-year males taking up territories in mid-
to late-April near Chicago. Orians (1961a) notes that some first-year male Red-winged Blackbirds are reproductively mature during the breeding
season. Catawba area banding returns showing 20 first-year males trapped in April and early May of 1967, and not again until after the nesting season in late June or July (Table 6), reflect generally de
creased flocking behavior at this time. The greatly diminished local feeding flocks containing primarily first-year males by mid-May (p. 21)
seem to indicate a relatively slower development of any territorial be haviorism on the part of first-year males. Since most of the nesting territories contained two to three females, and few females were report
ed in local roosts during the nesting season, it is likely that most first-year females do nest. Red-winged Blackbird nesting studies have
shown the usual secondary sex-ratio to be about 50:50 (Williams, 1940;
Orians, 1961a).
Although many local Red-winged Blackbirds are well into the nesting cycle by early May, much of the May migration at Catawba Point and Point Pelee consists of adult males and females (Tables 1 and 2), all poten
tially breeding birds. Some Red-winged Blackbirds were observed flying
southward from Point Pelee as late as May 31 (Gunn, 1951). Manwell
(1941) states that though this species has a strongly developed homing
instinct, certain individuals seem to exhibit this much more strongly than others, and Nero (1956) notes that only about half of the breeding birds return annually to the same marshes to nest. Orians (1961b) says that the size of the breeding Red-winged Blackbird population is deter mined primarily by the size of the marsh (among marsh-nesting birds).
Territorial behavior undoubtably also limits the breeding density.
Territorial studies (Nero, 1956; Orians, 1961a) typically show the rapid reoccupation of territories from which regular occupants are removed, indicating a ready excess of breeding birds. The breeding density with in a limited nesting habitat approaches a maximum, and "any surplus is obliged to overflow into less favorable habitats, until these are like wise filled up" (Wynne-Edwards, 1962:151). The presence of adult males and females in the trans-lake flights during late spring may reflect the persistence of migratory movement in potentially breeding Red-winged
Blackbirds until a suitable nesting situation becomes available. Migra tory restlessness, the laboratory equivalent of migration, persists through the summer months in many avian species when the breeding situ ation does not occur (Marshall, 1961; Lack, 1960b). Packard (1937) notes the similar late-spring wanderings of a number of potentially breeding Red-winged Blackbirds at Cape Cod marshes, sane leaving the area for up to two months before returning to nest or disappear again. 53
Such a behavioral pattern would seem of great survival value in the dis
semination of this highly-adaptable species. Orians (1961a) suggests
that the evolution of the slow maturation rate in male Red-winged Black
birds must be related to the presence of surplus breeding populations.
Many first-year males from nesting areas south of the lake (banded as
juveniles while wandering north across the lake the previous summer) fly northward across the islands during the spring (Table 6).
The schedule of nesting activities at Catawba agrees closely with the dates outlined by Allen (1914) at Ithaca, New York. Giltz (personal communication) notes that nesting usually begins on about the same date throughout Ohio without regard to latitude. First nests with full clutches were recorded in the Catawba area by late April. These were in the thickest stands of cattail growth from the previous year, while later nests were often in new cattail growth (p. 19). Smith (1943) notes a direct correlation between nesting success and the relative density of nesting cover in marshes and ponds near Chicago, and Nero (1956) states that Red-winged Blackbirds do not often have successful second nestings, single broods being usual, near Madison, Wisconsin.
Adult males in the Catawba area were observed to fly from the ter ritories to local roosts until the young began to fledge, at which time they began to remain at the territory overnight (p. 17). The adult males often feed the young birds (Orians, 1961a; Beer and Tibbitts,
1950); Giltz (1966) says that fledglings are cared for chiefly by the male in ground vegetation near the nest. According to Allen (1914), the first brood should fledge by about June 8, and probably remain with the 5*1 parents for an additional ten days or more. First juvenile Red-winged
Blackbirds were recorded in Catawba area roosts about June 20 (p. 17), and in the trans-lake flights during the following week (pp. 29 and 36).
Feeding Flock Behavior
The composition and relative size of local feeding flocks through out the year reflect both the resident and transient populations in the area, as well as a relative level of their changing gregarious or terri torial tendencies.
During the spring months, flocks of migrants are seen feeding with local residents. The changing composition of migrating Red-winged
Blackbirds, as well as the simultaneous build-up of resident populations, are reflected in the local feeding flocks during March and April. The territorial birds begin to remain in the marshes for increasing periods of time and this element eventually drops out of the upland feeding groups which by mid-May reflect chiefly late migrants and the non-terri torial local birds. As the nesting season approaches, increasing ter ritorial behavior and diminishing numbers of migrants are indicated as the large feeding flocks decrease in size and effectively disappear during late May and early June.
By late June, territorial behavior begins to wane. The non breeding first-year males and juveniles from the first broods, as well as some adults, begin to flock together. Throughout the summer and ear ly fall, feeding flocks become progressively larger and more segregated
(by both sex and age) as large additional populations of Red-winged 55
Blackbirds move into and through the western Lake Erie region. During
late August and early September, when large concentrations of relatively
stable populations are present, feeding flocks are typically large,
segregated, and consistent from day to day. By late summer, Red-winged
Blackbird flocks are usually fixed and highly organized (Dyer, 1964).
As the fall migration begins in September and October, the changing
compositions in the mixed flocks of migrants are again reflected in
local feeding areas as the juveniles and adults from north of the lake fly southward through the area. Juveniles seem to begin the southward movement, with some fall "resident” adults and juveniles remaining at
Catawba until early December (Table 4).
Local feeding flocks showed a high degree of consistency in the use of flyways and feeding areas on a day-to-day basis throughout the season, especially during the late summer (pp. 24-26). This would seem to indicate a stable core of resident Red-winged.Blackbird populations in local roosts utilizing specific feeding sites during extended per iods. Dyer (1967:772) states that Red-winged Blackbird "flight and feeding patterns are non-random and highly persistent within any one season."
If the flock is to be considered the basic social unit of the popu lation, a true "flock" probably consists of those individuals with most similar physiological conditions reacting to the common environmental stimuli which they share. Over fifty years ago, Cooke (1915) suggested that the internal state of the bird is primary, and environment secon dary, in initiating migration; Dyer (1964:113) says that Red-winged Blackbird flock establishment is "the overt result of basic physiologi cal change in each bird." For instance, those birds of the same sex and age class in a late-afternoon feeding aggregate which are ready physio logically to migrate at 1700 E.S.T., with proper environmental condi tions, will likely leave the mixed feeding group as a "flock" and fly in a given direction. Dyer (1964-) suggests that Red-winged Blackbird
"flocks," usually small following nesting, gradually build by repeated bondings between local sex and age groups until large discrete units of up to several thousand birds may be involved by late August and Septem ber. Local trapping data indicate that "flock" associations may last for extended periods of time; cases of trapping from two to six Red- winged Blackbirds of the same sex-age groups together (including juven ile birds) which had been last captured, together, up to eight months earlier were not ■uncommon. Many feeding, migrating, or roosting flocks may actually be groups of "flocks."
Roosting Behavior
The roosting populations of Red-winged Blackbirds in the Catawba area, like the local feeding flocks, reflect varying degrees of fluc tuation during most of the season, as the trans-lake migrants and wan derers move through the region. Separate blackbird populations frequent specific traditional roost sites (Dyer, 1964). Albers (1966) adds that by late summer, the amount of bird interchange between established flocks of Red-winged Blackbirds within a roost is very low. The most stable populations in the islands were shown during the breeding season, 57
when the roosting populations were greatly decreased, and for a few
weeks during late August and September before the heavy fall movements
began (Tables 3 and 4). The size of the local roosting colonies may
serve to direct the flow of transient populations throughout the year.
According to Wynne-Edwards (1962:298), "in the face of the constant
drift of transients, the roost-system appears capable of acting as a
continuous regulator of population-density in its own neighbourhood and of feeding the migrants through the region in an orderly progression.'*
Spring Movements
Red-winged Blackbirds do not usually spend the winter in northern
Ohio, although some do winter north of Lake Erie near Lake St. Clair
(Albers, 1966), and Tavernor and Swales (1907) reported a group of about fifty Red-winged Blackbirds wintering at Point Pelee in 1906-07. None were recorded wintering in the Catawba area in 1966 or 1967, and Jones
(1910) mentioned never noting any overwintering in the area. Winter banding recoveries (51 recorded) show that most of the Red-winged
Blackbirds banded in the Catawba area winter along the Atlantic and Gulf coast in the Carolinas, Georgia, and Alabama (Giltz, 1968a*, 1968d).
The Red-winged Blackbird commonly arrives in northwestern Ohio each year in late February. Jones (1910) records an early arrival date at
Cedar Point of February 26, 1906. Campbell (1940) reports an early arrival date for Lucas County, Ohio, thirty miles west of Catawba, of
February 18, 1933, and an average arrival date of March 1.
Temperature seems important in the timing regulation of Red-winged 58
Blackbird migration in the spring. Lincoln (1939) says that the north ward spring migration seems to follow the 35° F. isotherm (average tem perature line) as it moves north. He notes that Red-winged Blackbirds are unusual in that they move north with spring and don't wait several weeks and then "catch up" with it. Trautman (1940) agrees with this, noting that in warm winters, large flocks arrive at Buckeye Lake, in central Ohio, by the last week in January or the first weeks in February.
In 1966, early Ohio reports of northbound flocks (Giltz, personal communication) came on February 10, at Marietta, Ohio, on the Ohio
River. The initial Red-winged Blackbird flights at Catawba were ob served on February 20. In 1967, the first Red-winged Blackbirds at
Catawba were recorded on February 19 and 20. The high temperatures at
Catawba Point on these two days were 42° and 38° respectively, followed by an extended period of below freezing weather and no flights through
March 2. On March 3, 1967, (high temperature 35°) 1500 birds flew northward at Catawba. Temperatures dropped again, and no flights were recorded until March 7, when the maximum temperature was 28°. Nice
(1937), studying migration in central Ohio, noted that temperature had an obvious effect on early spring migration, although the 1967 early spring flights at Catawba may reflect a gradual decrease in threshold temperature levels during early March.
Often, the first spring flocks are composed entirely of adult males
(Allen, 1914), as was the case at Catawba in 1966 when no regular flights of females were observed until March 17. However, Jones
(1910:33) mentions that in some years "many early flocks contain both 59 sexes in nearly equal numbers." Some females were observed with the first flocks of adult males on February 20, 1967, at Catawba Point, though not regularly until March 18.
In general, the spring arrival pattern of Red-winged Blackbirds at
Catawba was similar to that described by Allen (1914) in his classic life history study done at Ithaca, New York. In 1966, the northward flights of Red-winged Blackbirds at Catawba Point began in late Febru ary and rose gradually to peak numbers in the flights by mid-April, after which they dropped steadily to minimal numbers by mid-May (Graph
I). In 1967, regular flights began in early March with a heavy influx of adult males, followed by a general influx in females and some first- year males in late March (Table 2). Several lesser movements (contain ing chiefly first-year males and females) were shown in the northward flights during late April and mid-May of 1967 (see Graph I). The ini tial large peaks shown during the spring of 1967 may reflect a greater influx of Red-winged Blackbirds than usual at this time due to the de layed onset of the northbound flights (p. 32). In general, large num bers of Red-winged Blackbirds flew northward daily from Catawba Point, and minimal distinct "waves" of migration were evidenced. Most varia tions in daily flight size at Catawba are probably attributable to local wind and visibility conditions over the lake (pp. 14 and 15). This type of steady migratory pattern also characterizes the spring and fall south ward flights of this species at Point Pelee, Ontario (Gunn, 1951; Jones,
1912). It reflects the movement of populations which begin migrating very early in the spring, with the staggered, gradual advance of 60 the various sex-age groups involved, flying relatively short distances northward each day. Such a behavioral pattern might well serve to dis perse the migrating populations rather uniformly along the "leading lines" of flight from the wintering grounds to the breeding areas. Sup plementary observations at the Columbus, Ohio, area for February and
March of 1967 indicate that once an initial front of northward migrating
Red-winged Blackbirds arrives in central Ohio, it can be expected to arrive at Lake Erie within a day or so. Banding data show that many of the same birds use the island flyways across the lake both in the spring and fall migrations (Table 6).
April banding reports show about twice as many first-year males
(95.1 percent transients) as adults (83.3 percent transients) present in the islands until late in the month when the numbers of adult males drop off (reflecting a decline in migrating numbers and an increase in territorial behavior) and those of first-year males rise to a final peak before dropping down to a constant level (13.2 percent residents) during the second week of May (Graph V). The overall trapped numbers declined sharply in May and the numbers of recorded "transient" first-year males
(86.8 percent of those banded) and adult males (52.1 percent) (see
Table H) are probably disproportionately high due to decreased flock- feeding behavior and a consequent reduced recovery rate, but this dif ference does point up the increased tendency among the territorial birds to remain near the territory sites to feed.
Numbers of females trapped in the islands and observed in the northward flights rose in mid-April and again in mid-May (Graph V). 61
Allen (1914) suggests that most of the resident adult females arrive
about mid-April, and that the resident first-year females arrive in mid-
May. The general decrease in the numbers of birds trapped during the nesting season resulting in a reduced rate of recoveries, made this dif ficult to ascertain. Considering the large numbers of birds involved in the Catawba flights at this time, many of these females were probably migrants; some resident females had already arrived in the area by late
March (p. 19).
However, those Red-winged Blackbirds trapped during the spring in the islands may represent primarily area residents for extended periods, with most of the transients tending to move on across the lake before dropping down to feed, and thus eluding the decoy-traps. There is some indication that spring and fall migrants are less likely to enter decoy traps than are residents or post-nesting transients. Largest numbers of birds were trapped in the islands during the summer while largest num bers were observed in the trans-lake flights during spring and fall.
Birds trapped in the islands throughout the season were primarily tran sients, but a higher proportion of "residents" was trapped during spring and fall than during the summer although island "resident" populations were larger during the summer.
Local feeding flocks of both males and females were recorded in the same feeding areas daily during mid-April and early May, reflecting basically stable area populations during late spring. Banding data also indicate progressively more stable local populations during late spring, with the drop in overall numbers trapped during the nesting season 62
attributed to increased territorialism. Thirty-four males (41.2 percent
adults) and six females were recorded in the Gatawba area during late
spring of 1967 and not again until June or early July (see Table 6).
Small southward flights at Catawba Point during early March proba bly indicate a reversal of flight direction over the lake islands on the part of some flocks before reaching the Canadian shore. The 30-mile trip across the lake at Catawba would require a flying time (at an esti mated average velocity of 30 m.p.h.) of about an hour. However, small numbers of Red-winged Blackbirds were occasionally observed flying south ward across Catawba Point prior to an hour after the initial northward flights had begun. Most of the major southward flights at Catawba (which began about mid-March) were recorded from one to three hours after the onset of the northward flights, were generally somewhat higher, and were often composed of different sex-age group proportions than those ob served in the northward flights. Moderate to heavy precipitation condi tions were often associated with flight-reversal movements (p. 15). A few large southward flights of early, low-flying birds in closely simi lar numbers and sex-age proportions to those in the northward flights at Catawba (attributed to flight-reversal) were shown in late March and early October of 1966 and 1967 (Graphs I and III). Since Catawba Point did not receive the regular large southward flights of Red-winged Black birds reported leaving the Canadian shore at Point Pelee during the spring (Gunn, 1951), most of the apparent southward "waves'1 observed there are considered to reflect only the relative degree of "coasting" shown during the southward trans-lake flights. 63
During February and early March, migration at Catawba occurred
chiefly in the morning. By late March and April, many Red-winged Black
birds were migrating at evening as well. Gunn (1951) notes.that although most of the spring southward flights of small passerines from Point
Pelee occur within one to four hours after sunrise, some of the "black bird" species (primarily Red-winged Blackbirds) were observed flying
southward at evening late in the spring. Increasing local species den- •
sity may lower social thresholds to migration producing evening flights; or earlier in the spring migration, lower temperatures and less avail able food along flyways may require additional feeding time for ade quate energy balance, resulting in the minimal evening flights.
Spring southward flights were often heavier at evening than in the morning, a situation which was probably the result of lower flight al titudes with decreasing light intensities and consequent increased
"coasting" across the islands. Evening flights at Catawba Point may therefore indicate more readily the relative magnitude of the southward trans-lake flights than morning flights. Small numbers of island- feeding birds from mainland roosts were probably also included in the evening flights south (p. 21).
During early May, occasional low-altitude, mid-day northward flights were noted at Catawba Point. These may represent a directional trend shown in feeding flocks of migrants, or possibly, a less-rigidly stylized migratory flight timing, typical of late migration. Some similar mid-day flights southward were also noted in late November. 64
Almost twice as many Red-winged Blackbirds were observed in north
ward flight during the spring at Catawba Point in 1967 (4-92,000 birds)
as in 1966 (253,100), whereas numbers of birds in the southward flights
remained relatively unchanged (143,100 and 126,400) (see Graph I).
This may reflect somewhat more complete observations of the northward
flights in 1967, and points toward a numerical consistency in the south
bound Red-winged Blackbird flights at Catawba within the two years.
The northward totals may also indicate larger numbers of birds moving
north of Lake Erie during the 1967 season than in 1966; the southbound
fall flights were comparably higher in 1967 as well, while mainland pop
ulations south of the lake may have been down somewhat (p. 18).
Reverse Migration
"While such terms as the 'normal' direction of migration for the
time of year, 'reversed migration,' and 'hard-weather movements' are
justified by the circumstances in which the movements concerned occur,
there is no clear line between them, and a movement either towards or
away from the breeding grounds may occur in any month, the likelihood of
its occurrence varying with the time of year and also with the direction of the wind" (Lack and Eastwood, 1962:393).
The classic concept of "reverse migration" involves an irregular direction of flight, often into a headwind (Pettingill, 1961). "The western end of Lake Erie is the only area in North America where the southward flight of small migrant birds is known to occur each spring"
(Gunn, 1951:i). During the spring of 1937, this phenomenon was first 65
noted at Pelee Island (Lewis, 1939). The spring southward flights
across Lake Erie have been observed most commonly when the wind is from
the south, and they have been known to include some sixty (mostly passer
ine) species (Gunn, 1948). Individuals banded on Point Pelee in the
spring have later been recovered on the Ohio mainland (Pettingill, 1964).
Numerous theories for this behavior have been set forth.
Lewis (1939:25) suggests that certain species may have an instinc
tive reaction to wind direction which is so irrepressible as to at
times cause flight that is "disadvantageous and even risky to the birds
that perform it." He mentions that all individuals of a species within the area at a given time may not react alike in this regard. During most of the spring of 1966 and 1967, Red-winged Blackbirds flew both
north and south at Catawba daily.
Pettingill (1964) suggests that some birds may "overshoot" or be
swept beyond the normal destination with high winds and would probably take the first opportunity to return. Williams (1950) adds that con
sidering the frequency of advancing cold fronts in the spring, it is un likely that most spring flights actually proceed in a north-south line.
He suggests that most courses are probably altered by weather conditions, and that birds must return to their regular paths along "abnormal" routes. Therefore, spring migrants may as likely arrive in Ohio from a northerly direction as a southerly, and probably from both directions.
However, Lewis (1939) notes that in some cases birds observed flying south from Pelee in the spring were species which did not nest in re gions to the south. When a passerine migrant over water flies into bad conditions, it can’t alight, so the ’’usual response is evidently to return on a re versed migration. Another type of reversed migration after putting out to sea is apparently due to the waning of the migratory urge" (Lack,
1959:388). In this case, with the 30-mile lake crossing requiring only about an hour, and with the island pathway across the lake, these pos sibilities are probably of little significance. Some writers have sug gested that because birds may become disoriented during overcast weather, most "reversed migration" would be expected to occur at these times (Lewis, 1939; Dorst, 1962). Most of the heavy spring southward flights of Red-winged Blackbirds at Catawba, however, were recorded in clear weather.
Temperature is a highly critical factor in the early spring mi gration of many birds (Richardson, 1966; Lack, 1963; Nice, 1937). Dorst
(1962:240) states that "migrants occasionally fly south in the spring when they encounter sudden cold fronts." Lack (1960b) suggests that temperature may have a directional effect on migration in the spring, and that "reverse migration" may represent an immediate response to temperature. Richardson, in a study of spring migration into southern
Ontario (1966), says further that above a certain temperature level, following winds are positively correlated with heaviest migration waves, and that opposing winds are highly significantly disassociated with major migration waves.
Gunn (1951) suggests that many of the spring southward flights of small passerines observed at Point Pelee are triggered by the same 67
short-term meteorological conditions which stimulate the normal north
ward advance of spring migrants as described by Bagg, et al. (1950). He
(1951:26) notes that heaviest southbound avian flights at Point Pelee
"occurred when the Pelee region lay within the western side of a high
pressure area or the warm sector of a low pressure area; conversely,
light or negligible southward flights occurred chiefly when the Pelee region lay on the eastern side of a high pressure area or the western
or northern sides of a low pressure area." Under these latter condi tions major northward flights were observed at Point Pelee (Gunn, 1951).
The Red-winged Blackbird flights northward at Catawba Point began early in the spring, and continued on a fairly constant basis until late May. Occasional peaks1 were shown, but relatively large numbers of ,
Red-winged Blackbirds appeared quite regularly in the northward flights during most of the spring and no distinct pressure pattern correlations were evidenced. Southward flights at Catawba were somewhat erratic, but this was expected due to its location on the trans-lake flyways.
Southbound flights of Red-winged Blackbirds leaving the Canadian shore at Point Pelee are also extremely regular in the spring, and show little correlation with the changing pressure patterns (Gunn, 1951). It seems evident, therefore, that the numerous avian species involved in the spring "reverse migration" phenomenon at Point Pelee are exhibiting dif ferent types of flight responses to the various prevailing stimuli, and are merely channeled into a similar flight pattern by the local geo graphy. Lack and Eastwood (1962) have shown that some species exhibit 68
a change in the direction of migration in certain geographic areas; that
the migrants' tendency to fly on an innate heading may be modified by a
tendency to "coast."
Some daily southbound flights of Red-winged Blackbirds at Catawba
Point occurred quite regularly beginning about a week after the onset of
the northbound flights each spring, and contained approximately the same
proportions of sex-age groups in the sequence shown earlier in the north
flights (Tables 1 and 2). A similar, more regular, southward movement
was observed at Marblehead during the spring (pp. 39 and 40). This sug
gested a steady movement of Red-winged Blackbirds across the lake from
the Canadian shore throughout most of the spring beginning about mid-
March. Observations at Point Pelee on April 7, 1966, and May 1, 2, and
3, 1967, days with high winds from the northwest, showed large numbers
of mixed male and female Red-winged Blackbirds flying southwest from the west shore of Point Pelee toward Pelee Island at altitudes of up to a thousand feet or more (p. 39). Most of these flights were visible only
through binoculars. As is the case with the trans-lake flights of Red- winged Blackbirds (p. 14), Lack (1960b) notes that most avian migrants
fly higher— sometimes extremely high— with following winds than with
opposing winds. This behavior probably helps to explain the frequent ground observations of apparently heaviest migratory flights occurring with "adverse" winds along "leading lines."
The spring southward flights of Red-winged Blackbirds across
Catawba Point and Point Pelee, most often reported as occurring with head winds, are probably the more readily obvious part of a previously unrecognized regular southward movement. This movement may be initiated
by thermal conditions during the early spring when the highest incidence
of flight-reversal behavior was indicated at Catawba (p. 62). General
ly, it probably reflects a type of "post-migratory wandering" (Packard,
1937; Gunn, 1951) wherein migratory movement persists in potential * residents which have not begun the nesting cycle. Such a behavior pat
tern might be expected in a species which migrates early in the spring
and commonly has surplus breeding populations (pp. 52 and 53), espe
cially as suitable marsh-nesting habitats are rapidly diminishing. The
first-year males involved in these flights may represent primarily
those which will not exhibit territorial behavior (p. 51), or they may
simply reflect a high degree of mobility among the non-breeding birds
and/or a tendency to flock with the potentially breeding wanderers.
Banding data show that first-year males from nesting areas south of the
lake commonly wander north from Catawba across the islands during the
spring migration (Table 6). The spring southward flights are directed by the peculiar geographic situation at Point Pelee, where high con
centrations of "coasting" birds are "funneled" steadily across the lake to Ohio.
Summer Movements
Following the nesting season, Red-winged Blackbirds flock to the marshy shores of bodies of water where they feed daily in nearby upland
fields and gather nightly in large roosting colonies in the marshes
(Trautman, 1940). In Ohio, this involves progressively increasing local
ized concentrations of Red-winged Blackbirds in the marshes surrounding 70 the small inland bodies of water and along the shore of Lake Erie during
July and August. The southern shore of western Lake Erie, like Sand
Lake, South Dakota (Dyer, 1964:112), "with its favorable roost habitat and nearby food supplies, is the major redwing concentration area" in
Ohio. Schneider (1968) suggests an estimated density of roosting Red winged Blackbirds along the south shore of Lake Erie near Catawba in late summer at two to three thousand birds per acre of cattail roost.
Trautman (1940) says that Red-winged Blackbirds at Buckeye Lake begin flocking in early June, and that the flocks are at first composed almost entirely of juveniles. During late June and early July, Catawba area roosts (which had contained chiefly first-year and adult males) began to receive increasing numbers of juveniles. Small, additional roosts began,to appear (p. 17) as more juveniles began to leave the nesting areas and flock together. This influx of juveniles into local roosts during the first week in July may be the result of the displace ment of the first-brood juveniles from the attention of the parents by the fledging of the second brood (Schneider, 1968).
Some adult males were often noted with feeding flocks of juveniles during early July, and adult males were observed accompanying juveniles in flights northward from Catawba Point at this time (pp. 23, 30, 36).
Packard (1936) saw little tendency for Red-winged Blackbird family groups to stay together after the young had fledged. However, Giltz
(1966) says that the adult male cares for the fledglings; and Schneider
(1968), working at the Ottawa Wildlife Refuge (25 miles northwest of 71
Catawba), noted evidence of the persistence of family units during July.
Bent (1965:14-5) states that "early in August, all the redwings seem
to disappear during the molting period, and are not much in evidence
until the middle of September or later." Allen (1914:105) ascribes this
"mysterious disappearance" to the movement of Red-winged Blackbirds,
first the adult males followed by the females and juveniles, deep into
the "heart of the marsh" while "handicapped" during the molting period.
Packard (1936) says that local Red-winged Blackbirds leave Cape Cod,
Massachusetts, in late July before molting, and Dyer (1964) adds that
Red-winged Blackbirds apparently molt en route to the wintering grounds.
Numerous molting birds were trapped in the islands and observed in the
Catawba flights from July through October, indicating little hindrance
to normal activities caused by molting.
Such a disappearance of Red-winged Blackbirds is commonly noted in most of southern Ohio, but along Lake Erie the situation is very dif
ferent. Catawba area roosts increased steadily in size from July
through early September. Banding data from the lake islands indicate
enlarging, highly fluctuating populations present dprang July and early
August, with only five percent of the birds banded in July remaining in
the islands for more than one week (Tables 3 and 4).
The northbound flights of males during most of July consisted of
about half adults (Tables 1 and 2). Large numbers of Red-winged Black
birds were still present in upland areas south of the Lake Erie area
until late July (Burtt and Giltz, 1967). Of the 14 adults recovered
during the nesting season south of the lake (p. 47) which had been 72 banded as juvenile birds near Catawba, all were banded in late July,
August, or September. Most of the Catawba flights during late June and early July were probably composed of local populations. Locally breed ing birds-("resident" during April, May, and June) were gone from the area by late July, and some of these birds were again present in the islands during late September and October (Table 6). Schneider's (1968) work suggests a similar exodus of adult males from the Ottawa Refuge
(Map I) following the nesting season, and a subsequent return during the fall migration.
Packard (1936) says that following nesting, the adult males are the first to leave the area, followed by the females and juveniles.
Late in July, greatly increased numbers of juveniles flew northward across the lake from Catawba, while the numbers of adult males flying north dropped off sharply (pp. 30 and 36). Banding records show one peak of adult males (96.7.percent transients) in the islands about mid-
July, corresponding with the initial northward flights at Catawba Point following nesting (Graphs II, IV, and VI). The numbers of adult males trapped then dropped steadily off throughout August.
Several distinct peaks of juvenile populations (85 percent transi ents) are shown in the island trapping data during July and early
August, continuing in some numbers through early September before drop ping off. Female population trends (95.3 percent transients) shown in the island traps were somewhat below, but closely paralleled those of the juvenile males (Graphs IV and VI). During both summers, several distinct waves of juveniles and females are reflected in the island 73 traps during late July and August corresponding closely with peak num bers and sex-age proportions in the northward flights at Catawba Point during this period. West of Catawba at the Ottawa Refuge, Schneider
(1968) reported that a roost containing an estimated 15-20 thousand Red winged Blackbird juveniles and females was vacated in late July of 1966.
Forty-three percent of the males banded in the islands during July were adults, as compared with 13.9 percent adults banded in August. Adults composed 23.9 percent of the "resident'1 island male populations during
July and only 5.6 percent during August (Table 4). Large numbers of juveniles were recorded in the northward flights at Catawba until; early
September, when they too dropped off sharply. Banding recoveries sug gest that many juvenile birds immigrate from southeast of Catawba fol lowing the nesting season (p. 4-7).
Allen (1914) notes that, following nesting, juvenile Red-winged
Blackbirds are commonly associated with adult females. Since females were not aged in flights or traps, this could not be verified. However,
Catawba flights contained some females throughout the summer, and band ing results show numbers of combined adult-juvenile females trapped in the islands paralleling both the adult and juvenile male peaks (Graphs
IV and VI), indicating that adult and juvenile males and females may show similar movement patterns during this period despite segregated adult flocks. Adults flew north across the lake following the nesting season in early July, but the largest northward movements at Catawba during the summer months were those of juveniles from late July through early September. Jones (1912:174), working in the lake islands in 1910, 74-
says, "the predominant (Red-winged Blackbird) plumage was the post juve-
nal, until late in August."
Southward flights at Catawba Point during the summer were limited primarily to small groups of mainland-roosting birds, feeding daily in
the islands. Southern Essex County, Ontario, on the north shore of
Lake Erie opposite Catawba, is a relatively dry region with little marsh area available for roosting concentrations of Red-winged Black birds. Observations at Point Pelee on July 5, 6, 20, 21, and August 9,
and 10, 1967, showed no evidence of any southward' trans-lake flights of Red-winged Blackbirds from Ontario (p. 39).
Sharply increasing numbers of juveniles flew northward across the lake islands during July and early August (Graphs IV and VI) to marshy areas of eastern Michigan and southwestern Ontario (12 band recoveries) where they remained for four to eight weeks (Table 5). Many of these same birds flew south across the islands during late September and
October along with migrating adults from areas to the north (pp. 40 and
4-1). Three hundred and fifty-four juvenile male Red-winged Blackbirds, present for a few days in the islands during the periods of heavy northward flights of juveniles in late summer, were absent an average of 52 days before again being recorded there during the fall months
(Table 5). Since many southward flights occur east of the Bass Islands, many of the trans-lake fall flights were not represented in the Bass
Island traps, whereas most of the northward flights during late summer probably were. Lincoln (1939) notes that late summer "vagrancy" is later counteracted by a directional migratory impulse which sends the 75 wanderers to their usual wintering grounds. Tavernor and Swales (1908:
125), working at Point Pelee, state that Red-winged Blackbirds "migrate heavily from the last of August or earlier while the species seems to remain stationary in point of numbers until late in the fall."
The Red-winged Blackbird populations reflected in the island traps represent those birds that are using the trans-lake flyways (most of the transients) and the small island populations ("residents"); they are not directly indicative of any stable mainland populations. Ninety percent of all island "resident" males from July through September were juveniles (Table 4). Relatively few adults were observed in the trans lake flights or caught in the island traps during late summer, while local roosting populations were increasing rapidly. At this time, the predominantly-adult mainland feeding flocks (p. 24), the presence of all-adult mainland roosting colonies (p. 18), and large numbers of adults reported in the corn-producing areas south of the lake (Giltz,
1961) seem to reflect enlarging, but relatively stable mainland popu lations of adult Red-winged Blackbirds (not emigrating to the north at
Catawba) along the south shore of Lake Erie. Albers' (1966) study at
Lake St. Clair, 40 miles north of Catawba Point, shows that in August, adults had established stable, highly-organized flocks within specific roosts, whereas groups of juveniles continually moved from marsh to marsh. Thousands of juvenile Red-winged Blackbirds flew northward across the lake from Catawba and appeared as transients in the Bass
Island traps at this time. Dyer (1964) notes that relatively few juvenile Red-winged Blackbirds frequented the main roost sites of 76
adults at Sand Lake, South Dakota, during late summer. In general, a
tendency in juvenile Red-winged Blackbirds to flock together in highly
mobile units, moving through and away from major roost areas of the more
stabilized adult populations in late summer seems to be indicated.
Dorst (1962) suggests that a high species density may stimulate
avian movements. Along the south shore of Lake Erie, the density of
Red-winged Blackbirds in local roosts increases progressively from the
end of.the nesting season until September. Wynne-Edwards (1962:299)
states that a primary function of roosting may be to "stimulate the ad
justment of population-density through emigration, when the economic and
social pressure proves to be sufficiently high." It seems possible that
the steadily growing number of adult Red-winged Blackbirds along the
south shore of the lake during July and August serves to push the less-
stable populations of juvenile birds from the major roost concentra
tion areas. Moreover, since some juveniles were present in the area
during the late summer, it may be the sharp local increase in the over
all species density which stimulates emigration.
A phenomenon known as "post-nesting wandering" has been observed
in the young of many birds, especially those species associated closely with water (Van Tyne and Berger, 1959). It is usually described as general movements away from the nesting area in late summer, and some
times assumes a particular direction (Pettingill, 1961). The late sum mer northward flights of juvenile Red-winged Blackbirds at Catawba
Point probably represent such a wandering phenomenon, with most of the
local movement directed northward by the peninsular "funnel" situation 77
at Catawba on the south shore of the lake. North of Lake Erie, many
juvenile Red-winged Blackbirds were present in major roost sites with
adults during the late summer (Albers, 1966). Data gathered in a simul
taneous banding program (Giltz, 1968c) at the Ottawa Refuge, indicate
that there may be a similar northwesterly trend of "coasting" Red
winged Blackbirds around the western end of Lake Erie at this time of
year, with some of these birds flying across the islands during fall migration (Table 7).
Dyer (1964) suggests that most Red-winged Blackbirds do not devel
op stereotyped flight behavior as juveniles, but on the basis of experi
ence gained as adults. Following nesting, distinct movement patterns
are reflected among the adult and juvenile Red-winged Blackbirds in the
Catawba area, but this difference does not become apparent until late
July and August. Many adults flew north across the lake from Catawba
Point during July; 42.9 percent of the (3245) males banded in the lake
islands during July were adults (Table 4). Many Red-winged Blackbirds, present in the islands during the summer or fall of 1966, were next recorded there as (adult) transients during the summer of 1967 (Table 6).
Local nesting season residents were gone from the area by August of 1967 and some were again present as transients in the islands during the fall
(Table 6).
Apparently some adults traditionally fly across the lake following nesting to roost concentration areas further north, perhaps indicating a tendency in some Red-winged Blackbirds to imprint to general geogra phic areas used as juveniles the previous year. Adult Red-winged 78
Blackbird flocks use post-nesting concentration areas "in as specific a
manner as they select breeding grounds" (Dyer, 1964:14-7). But post
nesting "residents" in the islands (90.7 percent juveniles) did not re
turn to.stay the following year, although some flew north across the
lake following the nesting season. Five juvenile males and one female,
"residents" during the summer of 1966, and four "resident" juvenile
males during the fall of 1966 were present as (adult) transients only
during the period of heavy northward flights in July and August of 1967
(Table 6). In summary, both adult and juvenile Red-winged Blackbirds
tend to establish distinct flocks (p. 56) following the nesting season,
although those of adults seem to become stabilized in specific post
nesting concentration areas whereas -those of juveniles remain highly
mobile throughout the summer.
Summer flights (Graph II) northward at Catawba were much heavier
than the southward flights in both 1966 and 1967. Somewhat higher
northbound totals for 1967 (215,600) than 1966 (166,100) reflect larger
numbers flying across the lake earlier, during July, in the 1967 season
than in 1966 when more Red-winged Blackbirds flew northward during
August and October. The southward flights in 1967 (49,800) may reflect
somewhat larger island-mainland feeding populations than those of 1966
(31,600), and perhaps a higher incidence of flight-reversal during the
heavy July northbound flights of 1967.
I 79
Fall Movements
During September, island Red-winged Blackbird populations, con
sisting primarily of juvenile males and females, became relatively
stable. Numbers of new birds being trapped dropped to 21.6 percent of
those trapped in August (Tables 3 and 4). Red-winged Blackbird popu
lations near Columbus, Ohio, may exhibit a similar pattern of stabili
zation in September (Burtt and Giltz, 1967). Forty-four percent of the
juvenile males banded in the islands remained for periods of more than a week compared to 20.4 percent in August and 7.9 percent in July
(Table 4). The lowest percentage of transient Red-winged Blackbirds in the islands from July 1 through November was recorded during September
(Table 4), and 18.2 percent of all birds banded stayed in the area over two weeks for an average period of 30 days. Predominantly-adult main
land feeding flocks and juvenile-female island flocks showed increased day-to-day consistency in feeding areas during late August and Septem ber (p. 25). Trans-lake flights both north and south dropped to daily constants of several hundred adult and juvenile birds (Graph II), which probably represented core island-mainland feeding populations (p. 24).
Only 9.1 percent of the adult males banded remained in the islands for more than a week during both August and September (Table 4).
In late summer of 1967, local Red-winged Blackbird roosts decreased greatly in size (see p. 18). The large mainland roosting populations, composed primarily of adult birds, did not move northward from the area
(across the lake at Catawba) in late August. Emigration was presumably to regions south of the Lake Erie roosts. Later in September, Catawba 80
area roosts were again invaded by large numbers of Red-winged Black birds, prior to the initial heavy trans-lake movements from the north.
In late September, southward flights increased somewhat as juven
iles began returning south across the lake (pp. 31 and 38). Three hun
dred and eighty-one male Red-winged Blackbirds (93 percent juveniles)
and 60 females, absent from the island traps for a month or more during
July and August, were again recorded there in the fall, beginning in mid-September (Table 5). A similar trend is indicated in banding data
collected on the south shore of Sandusky Bay (12 miles south of Catawba
Point; see Map II) during the simmer and fall months of 1964 and 1965
(Giltz, 1968a). Jones (1912:185), studying Red-winged Blackbird trans lake migration in the fall of 1910, notes that "one of the surprising things...was the evident southward movement of young birds ip advance of the old ones." There is some evidence (Table 5) that this southward movement of young birds may begin as early as late August on a small scale. During September and October, 29 percent of the (1229) juvenile male Red-winged Blackbirds recovered in the islands had been absent from the area for an average of 52 days.
In early October, increased numbers of juvenile male and female
Red-winged Blackbirds began flying northward from Catawba, reaching maximum numbers by mid- to late-October, and dropping off completely by
November. These October northbound flights were recorded in both 1966 and 1967, although they were much heavier in 1966 (see Graph III). Two juvenile male-female peaks in island trapping during mid- and late-
October of 1966 correspond closely with the periods of heaviest fall northward flights at Catawba Point (Graphs III and IV), whereas a lesser increase in trapped numbers was shown in October of 1967 (Graph VII).
Some indication of flight-reversal behavior was noted during early Octo ber of 1966 (Graph III). These October northward flights occur as local species density is again increasing with the arrival of the initial fall migrants from north of the lake, and probably represent a delayed con tinuation of the late summer northward flight phenomenon exhibited by many juveniles. These flights may also indicate the initial fall migra tion of weakly-oriented juvenile birds. Gunn (1951), working in the
Pelee region, states that the "reverse" flights across Lake Erie are evident only in the spring. However, the summer and fall northward flights of Red-winged Blackbirds recorded at Catawba Point reflect a
"reverse" flight situation which is effectively the opposite seasonally and geographically of the spring "reverse migration" pattern shown at
Point Pelee.
Some birds typically show territorial behavior in the fall of the year (Wynne-Edwards, 1962). Several instances of flocks of male Red winged Blackbirds singing during late summer and fall have been reported
(Jones, 1912; Saunders, 1948; Mehner, 1950). In late August and Septem ber, many Catawba area males, including some juveniles, exhibited terri torial-associated behavior including vocalization individually and in groups, display, and chasing, (p. 20). This may be brought about by a response to environmental stimuli similar to those present during April, when spring territorialism is typically exhibited. Gibb (1961) mentions that fall territoriality may help to initiate avian migration by restricting the population density. The proportion of the local popula
tions which would be forced into new habitats would assumably be greater
the higher the species density. It is conceivable that this type of
situation might produce a wandering phenomenon, especially in the less-
stable juvenile populations where fall migration cannot be goal-oriented.
By mid-October, numbers of Red-winged Blackbirds in the southbound
trans-lake flights, containing both juveniles and adults, begin to rise sharply (Graph.’III). Banding data show an increasing number of tran sient adults and juveniles traveling through the island area during
October and November (Tables 3 and 4). Peak transient populations were present during late October and early November of both 1966 and 1967, with distinct juvenile male-female and adult male-female waves shown in late October and early November of 1966 (Graph IV). The juvenile male-
female peaks correspond closely with the peaks in northward flights at
Catawba, whereas the adult male-female -peak in early November corres ponds with a peak in the southward flights and minimal north flights i (Graph III). Fall migrants included some of the same adult birds pre sent there as transients during the spring migration and/or the previous fall (Table 6), and many of the juvenile males and females recorded there during July and August (Table 5). Adult and first-year male
"residents" in the islands during the nesting season were recorded there during fall migration (Table 6). Numbers of recoveries during the fall migration were probably disproportionately low because the primary south ward flyway across the western end of the lake lies east of the Bass
Islands (Map I). Small stable island populations of juveniles and some 83 adults were also shown in the fall (Tables 3 and 4-). Dyer (1964-) notes that Red-winged Blackbirds may typically exhibit such a "leap-frog11 type of migration during the fall,, a phenomenon shown by several other avian species. Peak populations of migrating Red-winged Blackbirds are pre sent in central Ohio in late October and November (Burtt and Giltz,
1967).
During October and November, 79.7 percent of the island "resident" males were juvenile birds, remaining in the islands an average of 25 days (Table 4). As during the summer months, the island "residents" did not return to stay the following year. Four "resident" juvenile males during the fall of 1966, were present in the islands as transients only the following summer (Table 6). By late November, some residents were still present in the area (Tables 3 and 4). Jones (1912) says that most of the Red-winged Blackbirds had gone south from Cedar Point by the third week in October, with some remaining past the middle of November.
A few adult and juvenile males and an occasional female were still pre sent in the Catawba area during early December of 1966 and 1967.
Lack (1963) mentions that in his radar studies, temperature had no apparent effect on avian fall migration but that wind direction seemed to be a prime factor, with heaviest flights highly correlated with following winds. This observation was difficult to check with Red winged Blackbirds at Catawba Point where southward flights with follow ing winds usually occurred at high altitudes with minimal "coasting" effects. All northbound flights of 2000 or more birds did occur with following winds during October of 1967, and over half of the heavy fall southward flights recorded during 1967 occurred with northwesterly winds
(Table 2). However, as during the spring migration, reports from Point
Pelee at the north end of the southward trans-lake flyway indicate
highly regular daily flights of Red-winged Blackbirds crossing the lake
during the fall, with minimal distinct ’’wave11 movements shown (Jones,
1912; Wood, 1910). Daily observations of some southbound flights at
Catawba during the fall months tend to support this, as the apparent
"waves” observed there (GrapH'III) are due primarily to "coasting"
effects (p. 62). Peaks in the Catawba northward flights during late
summer and fall are probably functions of the increasing species den
sity locally. Since immigration to local roosts occurs chiefly from the
southeast during late summer and from the north during October, correla
tions with southward flights at Catawba (reflecting trans-lake "coast
ing") would be meaningless.
Red-winged Blackbird trapping patterns shown at Columbus, Ohio,
(Burtt and Giltz, 1967) seem quite similar to the patterns shown in the
Bass Island traps, with a decrease in trapped birds during September,
and a. sharp increase shown during October and November. Columbus, loca
ted on the Scioto River, probably represents a major migratory pathway
(p. 46), as do the Lake Erie islands. Red-winged Blackbird trapping at post-nesting roost concentration areas (near water and abundant food
supplies) such as those south of Sandusky Bay (Giltz, 1968a), at the
Ottawa Wildlife Refuge (Giltz, 1968c), and east of Columbus at Buckeye
Lake (Danner and Stone, 1968), reflects a progressive build-up in local populations during August and September, followed by a sharp drop in 85
trapped numbers during fall migration. Roosting populations south of
Sandusky Bay typically increased in numbers during late summer (probably
due both to immigration and the progressive amalgamation of initially
small roosting populations), as did those at the Ottawa Refuge
(Schneider, 1968) and at Lake St. Clair marshes (Albers, 1966). Con
versely, island roosting populations decreased during September and then
rose again during October and November, as did those near Columbus
(Giltz, personal communication).
The northward flights during the fall of 1967 (38,900) were not as
heavy as those observed in 1966 (148,600) (see Graph III). If these
fall northward flights do represent a delayed continuation of the sum mer flights, the higher number of northbound birds during the summer of
1967 (215,600) than in 1966 (166,100) may account for the difference
shown in the fall movements (Graphs II and. III). If the northward move ment is a density-dependent behaviorism, decreased local populations in
1967 may be indicated. The greatly decreased numbers of Red-winged
Blackbirds in local roosts during early September of 1967 (p. 18), when populations showed most stability, might tend to support this.
Southward movements observed in the Catawba area during the fall of
1967 (267,600) were considerably greater than those recorded in the fall of 1966 (82,100) (see Graph III). This difference is still not as great as that recorded during the spring northbound flights of 1966 (253,100) and 1967 (492,000) (Graph I). Trans-lake northward flights are more completely represented at Catawba Point than are southbound movements; larger numbers of Red-winged Blackbirds moving north of Lake Erie (in the spring and southward in the fall) during the 1967 season seem to be indicated. A part of this difference may also be due to a higher inci dence of "coasting11 flights, and to more complete coverage of the fall southbound movements in 1967 via supplementary observations at Point
Pelee and Marblehead, and the assistance of Dr. M. A. Miskimen and
Dr. L. S. Putnam in tracking the southbound flights across the lake islands. SUMMARY AND CONCLUSIONS
This study examines the data collected on 399 days of flight observations at Catawba Point, Ohio, and the results of an island banding program carried out during 1966 and 1967, together with sup plementary general field data for this period, and discusses the gross movement patterns and behavior of Red-winged Blackbirds in the western Lake Erie region indicated by these methods.
A major northward Red-winged Blackbird flyway across the western end of - Lake Erie begins at Catawba Point and continues north across the Bass Islands to the Canadian shore east of Colchester, Ontario.
About 800,000 Red-winged Blackbirds were observed to fly northward from Catawba Point each year from February through November. The
Catawba flights occurred within several hours after sunrise and before sunset, and generally spiralled upward to altitudes of a thousand feet or more over the lake. Lower-altitude trans-lake flights associated with heavy headwinds or precipitation conditions often followed the more contiguous diagonal pathway across the islands between Catawba and Point Pelee, Ontario. A southward flyway extends from Point Pelee across the islands to Marblehead and Catawba. Many of the same Red winged Blackbirds (161 band recoveries) used the island flyways during the spring and fall migration annually.
87 88
Large numbers of Red-winged Blackbirds (approximately 400,000 observed), including first-year birds from nesting areas south of the lake (35 band recoveries), flew steadily northward across Lake Erie each spring, with little of the "wave" migration shown by many species.
Spring flights of Red-winged Blackbirds traveling south across the lake to Catawba and Marblehead apparently represented a regular southward movement which began about a week after the onset of the northward trans-lake flights in late February. This phenomenon may be associated with thermal conditions early in the spring, and probably represents a
"post-migratory wandering" among potential residents which have not be gun the nesting cycle. It reflects the "funneling" of localized high concentrations of migrants "coasting" southward from Point Pelee.
Following nesting, Red-winged Blackbird populations from south of the lake flew northward (approximately 200,000 birds annually) to Cana da, and back south across the lake (441 band recoveries) during fall migration. Local species density increased progressively through July and August as many birds moved into the roost concentration areas near
Catawba from the southeast (14 band recoveries). During late summer, large mainland populations of adult Red-winged Blackbirds became rela tively stable (trans-lake emigration ceased), while highly mobile ju venile populations continued to fluctuate, moving through the south shore roost areas of adult birds and "coasting" northward across the lake islands from Catawba Point (Island banding records: 92% transients in July; 80% in August). Many of these juveniles (354 band recoveries) 89
flew back across the islands with adult Red-winged Blackbirds from
north of the lake during fall migration. Post-nesting island "resi
dents" (90.7% juveniles) did not return to stay the following year
but flew north across the lake following the breeding season. As migrants from the north began to fly southward during the fall (again
increasing local species density), juvenile males and females again moved north across the islands from Catawba in October (148,000 ob
served in 1966). APPENDIX
90 91
TABLE 1 MORNING AND EVENING FLIGHT TOTALS 1966
Morning Flights Evening Flights Date F° Wind North M*F*Y* South M F Y F° Wind North M F Y South M F Y
2-20 31 6W 50 2 0 0 10 1 0 0 2-27 32 5NW 300 2 0 0 25 2 0 0 35 5NW 125 1 0 0 50 2 0 0 3-4 44 8W 1000 1 0 0 50 1 0 0 55 6SW 600 2 0 0 200 3 0 0 3-5 32 9W 1500 3 0 0 75 1 0 0 37 0 200 0 0 0 200 2 0 0 3-7 20 17SW 500 1 0 0 200 3 0 0 3-12 50 4SW 300 3 0 0 600 2 1 0 3-13 38 4SW 3900 2 0 0 700 1 0 0 42 0 1900 3 0 0 700 2 0 0 3-14 28 0 1800 1 0 0 50 2 0 0 3-17 34 0 2000 2 0 0 100 3 0 0 68 5S 3900 3 0 0 2300 3 1 0 3-18 53 23S 1600 1 0 0 4300 3 3 0 46 20S 1000 1 0 0 2000 3 0 0 3-19 39 8SW 1300 2 0 0 3300 3 3 0 40 23SW 50 2 0 0 700 2 0 0 3-20 35 13W 1500 2 0 0 100 1 0 0 40 2SW 1500 1 0 0 1500 3 1 0 3-21 38 2NE 1100 1 2 0 200 1 0 0 57 6SE 1100 2 1 0 3100 2 2 0 3-22 58 15SW 6700 2 3 0 5500 3 3 0 68 0 800 2 1 0 300 1 0 0 3-23 50 4NE 5100 3 3 0 1800 2 1 0 58 23SW 100 1 0 0 2300 3 1 0 3-24 28 20SW 2800 2 3 0 4200 3 2 0 28 25W 0 --- 800 3 0 0 3-25 21 20W 1020 1 1 0 1370 3 0 0 38 8W 50 1 1 0 350 2 1 0 3-26 28 15NE 1240 2 2 0 950 2 0 0 30 15NW 200 2 2 0 0 --- 3-27 22 8NW 1500 3 0 0 50 1 0 0 30 5N 1400 1 2 0 30 1 0 0 3-28 25 15NW 3400 1 3 0 500 2 1 0 38 8NW 1200 2 1 0 175 2 0 0 3-29 25 4NW 5500 1 3 0 1700 1 1 0 42 10NW 200 1 2 0 300 2 1 0 3-30 37 5NW 2300 1 3 0 700 2 0 0 3-31 48 16NW 500 1 1 0 3100 3 3 0 4-1 41 10NW 7100 2 3 2 800 1 2 0 52 25NW 20 1 0 0 1200 1 2 0 4-2 34 20NW 1400 1 1 1 50 1 0 0 44 15NW 0 --- 200 1 1 0 4-3 36 0 1000 1 2 1 1650 3 2 0 35 15NE 50 0 1 0 200 2 0 0 4-4 38 3NE 4400 2 3 2 500 0 1 1 42 7NW 1700 1 1 1 10 1 0 0 4-5 34 15NW 4200 1 3 3 4650 3 0 1 39 10NW 50 0 1 1 350 1 1 0 4-6 33 10W 2450 1 2 2 650 3 2 1 40 10 SW 20 0 0 1 500 1 1 0 4-7 35 10NW 1400 0 1 3 600 1 1 1 39 25NW 450 1 1 1 10 1 0 0 4-8 30 10NW 6400 1 3 3 300 2 0 1 40 5NW 350 1 2 2 1100 2 1 1 4-9 34 10NW 4050 1 3 2 150 2 2 1 43 8NW 1650 1 1 3 110 1 2 0 4-10 31 10NW 7650 1 2 3 150 1 1 1 45 3NW 600 1 1 1 850 1 2 1 4-11 36 6E 900 0 1 1 150 2 1 1 4-12 39 35NE 20 1 0 1 400 2 1 1 4-13 38 35NE 4400 1 2 3 600 1 2 1 47 25N 1250 1 2 2 4000 3 2 1 4-14 35 5N 11150 1 3 3 125 2 1 0 4-15 41 5N 3400 1 3 2 175 2 0 1 50 7NE 500 1 1 1 1450 2 2 1 4-16 41 0 1700 1 2 2 50 2 1 0 54 3NW 600 0 1 1 1320 2 0 1 4-17 60 7NE 350 0 1 2 700 2 1 1 4-18 45 5SE 1100 0 2 1 200 1 1 0 66 7NE 1000 1 2 3 725 2 2 0 92
TABLE 1 (continued)
Morning Flights Evening Flights Date F° Wind North M F Y South M F Y F° Wind North M F Y South M F Y
4-19 58 2NW 4600 1 3 3 50 1 1 1 62 5SE 625 1 1 1 1400 1 2 1 4-20 61 10S 350 0 2 1 7000 2 3 3 66 5SE 150 0 1 1 3550 1 3 1 4-21 66 10SW 100 1 1 1 7900 2 3 1 54 3SW 2000 2 3 2 100 1 1 1 4-22 38 15E 2850 2 3 3 50 1 2 0 57 20NE 1350 1 1 2 450 1 1 1 4-23 48 12E .2500 1 2 2 1500 1 2 1 60 3NE 1400 1 0 2 400 1 2 1 4-24 56 12NW 3700 1 2 3 2950 1 3 2 64 3NW 50 1 1 1 1500 2 3 2 4-25 66 3NE 200 1 1 1 625 2 1 2 4-26 45 25NE 1450 0 2 3 100 0 1 1 45 35NE 150 0 1 2 50 1 0 1 4-27 48 35NE 2600 1 1 3 200 1 1 2 5-1 45 5NE 650 0 1 2 150 0 1 1 5-2 35 10NE 2200 2 2 2 50 1 1 0 49 7E 400 1 1 2 650 1 2 2 5-3 44 6SW 1400 0 1 2 4000 2 3 2 48 25NW 250 1 2 1 110 1 2 2 5-4 48 7SE 300 0 2 2 570 2 2 2 5-5 46 5SW 600 1 0 2 2350 1 3 2 5-6 55 5W 1050 1 1 3 1450 1 3 2 55 15NW 450 1 2 2 20 1 0 1 5-7 50 5NE 1000 1 1 2 700 0 2 1 5-8 48 15NE 2650 2 3 2 100 0 1 1 50 12NE 150 0 1 2 60 1 0 1 5-9 40 8NE 250 1 1 2 20 0 1 1 5-11 28 5NW 2225 1 1 3 50 1 1 1 51 2NW 150 1 2 1 150 2 0 1 5-12 44 20NE 1150 1 2 3 100 0 2 1 5-13 45 2 ONE 320 1 2 1 200 1 1 2 5-14 45 10NE 2100 1 2 3 50 1 1 1 60 3NE 350 0 2 2 150 2 2 2 5-16 70 4NW 320 1 3 1 50 2 0 2 5-17 50 2NW 150 0 1 2 50 1 1 0 64 15E 150 0 2 1 60 1 0 2 5-18 55 7E 100 0 1 2 50 1 1 1 5-19 68 10NW 20 1 1 1 50 1 1 1 5-20 51 4NW 50 1 0 2 10 0 0 1 5-21 52 0 75 1 0 1 10 1 0 1 5-23 50 3SE 50 0 1 2 10 1 0 1 70 5E 25 0 0 1 10 1 0 1 5-24 69 4NW 25 1 0 1 10 0 0 1 5-25 52 7NW 175 ? 1 2 10 1 0 1 5-26 71 4SE 20 1 0 1 65 1 1 1 5-27 50 5NW 170 1 0 2 10 0 0 1 5-28 50 20NE 40 0 0 2 10 1 0 1 5-30 51 10NW 10 0 0 1 120 1 0 1 5-31 48 12NE 220 1 1 3 15 1 0 1 58 5N, 5 0 1 1 60 1 0 1 6-1 65 3E 25 1 0 1 100 2 1 1 6-3 55 2SE 185 2 0 2 65 1 1 1 6-6 *5 72 7NW 10 0 0 1 140 2 1 2 6-7 64 10NW 140 1 0 3 25 0 0 1 6-9 58 25NE 160 1 0 2 10 0 0 1 6-10 64 15NE 10 0 0 1 140 1 0 2 6-15 60 15NW 170 1 l 3 10 1 0. 1 6-16 67 5NE 25 1 0 2 75 1 1 2 93
TABLE 1 (continued)
Morning Flights Evening Flights Date F° Wind North M F Y South M F Y F° Wind North M F Y South M FY
6-20 65 2W 220 2 1 2 20 0 1 1 6-22 80 2W 60 1 0 2 100 2 1 2 6-23 80 0 15 1 0 1 50 1 0 1 6-24 70 2NW 425 1 0 2 20 0 0 2 6-26 78 5W 70 0 0 1 80 1 0 1 6-27 75 5NW 400 1 1 2 10 0 0 1 76 4SE 25 0 1 1 50 0 1 1 6-28 72 4SW 250 1 1 3 40 1 0 1 73 2NE 10 0 0 1 20 0 1 1 6-29 70 0 150 1 2 2 40 0 1 1 6-30 76 4NE 20 1 0 1 10 1 1 1 7-1 75 10NE 240 1 1 1 15 1 0 1 75 10NE 175 1 1 1 50 0 1 1 7-2 76 8NE 100 1 0 1 125 1 1 0 7-4 78 5NW 1300 3 1 3 100 1 0 1 75 10NE 200 1 0 1 25 0 1 1 7-5 75 8NE 950 2 1 2 20 1 0 1 76 4NE 150 2 1 1 100 1 1 1 7-6 76 25NW 300 2 1 2 100 2 1 1 7-7 75 5NW 3725 3 2 3 120 2 1 1 75 20NW 1220 3 2 2 25 1 1 0 7-8 71 8NW 1400 3 1 2 75 1 0 1 78 4SE 210 1 1 2 60 1 0 1 7-10 72 15 SW 1525 2 1 3 125 2 1 1 7-11 73 6NW 3250 3 2 2 50 1 0 1 77 9W 140 1 1 1 750 2 2 2 7-13 73 9NW 300 1 1 2 20 1 1 1 78 5NW 400 3 2 2 50 2 1 1 7-14 70 15NE 140 2 1 2 20 0 1 1 70 20NE 40 1 1 1 20 2 1 0 7-15 74 15NE 70 2 1 1 10 2 0 1 7-16 74 20NE 600 1 2 3 50 3 1 1 7-19 75 20NE 100 2 1 1 10 2 0 0 7-20 70 2 ONE 275 2 1 2 40 3 1 1 7-21 54 4E 4200 3 3 3 350 1 1 1 7-22 55 5NW 2850 3 2 3 1150 2 0 2 80 3NE 100 1 1 2 60 2 2 1 7-23 80 3NE 75 3 1 2 45 1 0 1 7-24 70 3NE 3020 3 2 3 115 1 2 2 76 4NW 25 1 1 1 40 2 1 0 7-25 72 2N 2520 2 2 2 185 0 1 1 7-27 74 7NW 1300 0 2 2 60 1 1 1 7-28 73 4NW 1200 1 2 3 50 0 2 1 7-29 72 12NE 2700 1 3 3 40 0 1 1 7-30 75 2 ONE 290 1 2 2 170 2 1 1 7-31 71 10NW 7500 1 3 3 1000 1 3 3 80 7NE 120 1 2 2 350 3 1 1 8-1 71 4NW 7200 2 3 3 1850 1 3 2 72 3NW 10 0 1 1 50 2 1 1 8-3 66 20N 220 1 2 3 10 1 0 1 70 5NE 60 1 1 1 40 2 0 1 8-4 67 0 7050 1 2 3 1050 0 1 2 8-6 58 0 6050 0 2 2 300 0 2 1 8-7 58 3NW 3925 1 3 3 830 0 2 2 75 6NW 150 1 2 2 100 1 1 0 8-8 66 8S 1750 0 2 3 340 1 1 2 75 5SW 30 0 0 2 5 1 0 0 8-9 69 3W 4725 1 3 3 250 0 2 1 75 3W 70 1 1 2 25 2 1 0 8-10 65 2NW 1350 0 2 3 100 0 1 1 8-11 65 12NW 30 1 1 1 25 1 1 1 8-12 58 18NW 600 0 2 3 10 0 0 1 94
TABLE 1 (continued)
Morning Flights Evening Flights Date F° Wind North M F Y South M F Y F° Wind North M F Y South M F Y
8-13 60 2NW 4350 1 3 3 200 0 1 1 8-14 62 5SW 40 0 2 3 540 0 2 3 8-15 66 4W 4250 1 3 3 215 0 3 2 75 2W 20 0 1 1 15 1 0 0 8-16 70 18N 15 0 1 2 0 --- 8-17 75 2W 50 1 1 2 10 1 0 1 8-18 63 3NW 3350 0 3 3 350 0 1 2 85 4W 10 0 0 1 110 1 1 2 8-19 67 4NE 200 0 2 3 20 0 1 1 8-20 68 15NE 1100 1 3 3 70 0 2 1 8-21 70 10NE 700 0 3 3 0 --- 73 5NE 0 --- 50 2 0 1 8-22 72 2NW 850 1 3 3 560 1 32 75 20NW 300 1 2 2 275 3 1 1 8-23 69 20NW 40 0 3 2 60 1 1 1 72 20NW 200 1 1 2 425 2 2 2 8-24 ■ 67 15NW 700 0 3 3 1000 0 2 2 73 6NW 0 - - - ' 200 2 1 2 8-25 67 5NW 1000 1 3 3 20 0 0 2 8-26 70 6NW 1100 1 2 3 80 0 2 2 72 7NW 75 1 1 2 800 2 2 2 8-27 67 5NW 2450 1 3 3 250 0 1 3 78 4NW 10 0 0 1 60 1 2 1 8-28 69 5NW 900 0 2 3 50 0 2 1 8-29 70 2W 2420 1 3 3 500 0 3 3 75 0 0 --- 210 3 0 1 8-30 70 2N 1000 1 3 3 70 1 2 2 80 2NW 75 0 1 2 590 2 1 1 8-31 70 0 700 0 2 3 80 0 1 1 78 0 60 1 0 2 530 3 1 2 9-1 84 4NW 0 --- 450 3 1 3 9-2 68 4NW 1150 1 2 3 150 0 2 2 9-3 75 7NW 140 0 2 3 400 0 2 2 9-4 74 25NW 300 0 3 3 200 1 3 2 9-6 66 25NW 325 1 3 2 85 0 2 1 73 10NW 20 0 1 2 420 3 1 2 9-7 46 12N 700 1 3 3 10 0 2 1 76 5NE 0 - - - 600 2 2 2 9-8 65 5NE 550 0 3 3 10 0 2 2 75 7NE 60 1 1 2 570 3 1 3 9-9 62 2NW 275 1 2 2 20 1 0 1 9-10 75 0 0 --- 700 1 2 2 9-11 66 2N 1400 1 3 2 300 2 2 2 9-12 66 12E 700 1 3 3 0 --- 72 15NE 15 1 1 1 200 1 2 2 9-13 66 4SE 570 1 2 2 10 1 0 1 9-14 65 6S 540 1 2 2 470 2 1 1 71 0 1120 1 2 2 0 - - - 9-15 60 20NE 25 1 1 1 0 -- - 9-16 50 6NW 35 0 1 2 60 1 1 0 74 3NW 0 -- - 25 1 1 2 9-17 60 5NW 200 1 2 2 215 2 1 1 9-21 60 20E 50 1 0 2 0 --- 62 5NE 125 0 1 2 0 -- - 9-23 60 25NW 100 0 1 1 700 3 1 1 9-24 60 10N 260 1 1 2 250 2 0 1 68 10NW 300 0 1 2 40 1 1 1 9-26 55 6NW 310 2 0 2 1670 3 1 2 66 3NW 90 1 1 1 10 0 1 1 9-27 62 2N 1500 1 2 2 170 2 0 1 9-28 60 5NW 250 1 1 2 170 2 1 1 10-1 39 8NW 460 1 2 2 200 2 3 1 10-2 38 5SW 510 0 2 3 550 2 3 2 68 5W 0 -- - 25 1 1 1 10-3 56 5SE 2240 1 3 3 2275 3 3 2 68 20S 0 - -- 15 0 1 1 95
TABLE 1 (continued)
Morning Flights Evening Flights Date F° Wind North M F Y South M F Y F° Wind North M F Y South M F Y
10-4 63 5SW 160 1 2 1 125 2 2 1 10-5 48 25NW 4760 2 3 3 5230 3 3 3 10-7 48 15NW 50 0 1 2 5 1 0 1 10-10 49 25NW 450 1 3 3 90 1 1 2 10-11 48 25W 300 0 2 3 240 1 1 2 10-12 39 9NW 16400 1 3 3 1100 2 2 2 65 5N 25 1 1 2 5 1 0 0 10-13 58 10 SE 2330 0 3 3 60 1 1 2 10-14 58 15S 1670 1 3 3 930 1 2 2 70 20SW 25 1 1 1 220 1 2 1 10-16 40 25NW 250 1 3 2 560 1 2 2 50 20W 45 1 1 2 0 --- 10-17 55 12NW 150 0 2 3 400 2 2 3 10-18 43 5SE 1000 0 3 3 300 2 2 3 10-20 37 30NW 11470 1 3 3 4430 2 3 3 10-21 40. 10 SE 14630 2 3 3 3000 2 2 3 68 12SW 10 0 1 1 970 1 2 2 10-22 48 15S 380 0 3 3 550 1 2 3 10-23 50 7NW 11200 1 3 3 1070 2 3 3 10-24 45 6SW 3030 1 3 3 7260 3 3 3 50 6SW 0 --- 490 2 3 3 10-25 50 10NW 7725 0 3 3 220 1 2 3 10-30 40 8NW 17000 1 3 3 990 2 3 3 50 12SW 0 --- 2820 2 3 3 11-1 45. 10NW 930 0 3 3 50 1 1 2 11-3 33 25NW 5 0 0 1 80 2 1 1 11-4 32 15S 50 1 1 2 2000 3 3 3 35 30SW 0 --- 900 3 3 2 11-5 34 8W 20 0 0 2 400 3 2 2 37 3SW 40 1 0 1 1600 3 1 3 11-6 35 3SE 50 0 0 3 1270 3 3 2 40 6S 0 --- 1300 3 2 1 11-9 58 8SW 5 0 0 1 1800 3 3 3 11-14 34 10NW 10 0 0 1 5000 3 2 1 11-18 50 8NW 30 1 0 1 300 2 1 1 48 15NW 0 --- 20 1 0 1 11-23 45 5SE 0 --- 1400 3 0 2 11-26 32 8NW 0 --- 0 - - -
*Recognized sex-age proportions (M, adult male; F, female; Y , first- year or juvenile male): 1-few individuals observed; 2-moderate numbers observed; 3-many observed 96
TABLE 2 MORNING AND EVENING FLIGHT TOTALS 1967
Morning Flights Evening Flights Date F° Wind North M*F*Y* South M F Y F° Wind North M F Y South M F Y
2-13 28 0 0 --- 0 --- 2-15 30 5W 0 -- - 0 - - - 2-17 27 8NW 0 - - - 0 --- 2-18 23 2N 0 - - - 0 - - - 2-19 33 5SW 10 1 0 0 0 - -- 40 5S 0 - - - 0 - - - 2-20 35 8SW 200 3 1 0 0 -- - 30 12W 0 -- - 10 1 0 0 2-21 19 20NW 0 - - - 0 --- 26 20NW 0 - - - 0 - -- 2-22 27 12 SW 0 - - - 0 - - - 36 10W 0 - -- 10 1 0 0 2*23- 18 12N 0 -- - 0 -- - 2-24 15 8NW 0 -- 0 - -- 2-27 32 6W 0 -- - 0 --- 2-28 ;■26 18NW 0 - - - 0 -- - 3-1 ‘ 12 5NW 0 -- - 0 - - - 3-2 33 12 SW 0 -- - 0 -- - 3-3 32 12 SW 200 2 0 0 0 - - - 35 6NW 1300 3 0 0 0 -- - 3-4 27 5N 20 2 0 0 0 --- 3-5 30 6NE 0 - - - 0 - -- 3-6 27 8N 0 - - - 0 -- - 3-7 20 12W 50 3 0 0 0 --- 28 ION 50 2 0 0 0 --- 3-9 20 6N 200 3 0 0 50 2 0 0 36 10SW 800 3 0 0 100 3 0 0 3-10 38 8SW 750 3 1 0 200 3 0 0 52 8SW 9000 3 1 0 200 3 0 0 3-11 49 12 SW 21000 3 0 0 200 3 0 0 45 8N 6000 3 0 0 200 2 0 0 3-12 30 15NE 18500 3 0 0 100 3 0 0 35 12NE 5500 3 0 0 200 2 0 0 3-13 34 4E 8500 3 0 0 100 3 0 0 45 5NE 600 3 0 0 500 2 0 0 3-14 33 3NE 16100 3 0 0 150 2 0 0 36 5E 3500 3 0 0 300 3 0 0 3-15 33 15NE 11200 3 1 0 200 2 0 .0 35 ION 1000 3 0 0 150 2 0 0 3-16 30 15NW 150 3 0 0 450 3 0 0 3-17 18 25NW 350 3 10 0 0 - -- 21 15NW 200 3 0 0 0 - -- 3-18 21 0 4300 3 2 0 1400 3 0 0 3-19 15 6SE 500 2 1 0 150 3 0 0 40 3S 5500 3 2 0 1100 3 1 0 3-20 33 8SE 300 3 1 0 2000 3 1 0 34 5SE 200 2 0 0 1200 3 0 0 3-21 36 15 SW 4000 3 1 0 250 3 0 0 39 12W 1500 3 1 0 450 2 1 0 3-22 42 5W 7200 3 2 0 100 2 1 0 3-23 37 10NW 32000 3 3 0 1000 3 2 0 36 4W 3500 3 2 0 0 - - - 3-24 30 5SE 34000 3 3 1 300 2 1 0 37 10E 4300 3 3 0 1000 3 2 0 3-25 36 10E 5000 3 3 0 0 -- - 40 4SE 1000 2 3 0 1200 3 2 0 3-26 40 0 8000 3 3 1 150 1 2 0 47 5W 6000 2 3 0 200 2 1 0 3-27 58 10SE 2000 2' 3 0 8200 3 2 0 50 10SW 1300 2 3 0 150 2 1 0 3-28 40 3E 3500 3 3 0 300 3 2 0 3-30 68 2SE 2000 2 2 0 600 3 1 0 3-31 75 2S 2500 3 3 1 1000 3 2 0 4-1 62 8NW 13300 2 3 1 1800 3 2 0 97
TABLE 2 (continued)
Morning Flights Evening Flights Date F° Wind North M F Y South MF Y F° Wind North M F Y South M F Y
4-2 70 20NW 1000 2 3 0 3600 3 3 0 4-3 42 10NW 1000 2 3 2 800 2 0 0 47 20NW 200 2 3 2 0 -- - 4-4 28 12 SE 800 2 3 0 500 3 2 1 54 10SW 350 2 2 2 2100 3 3 1 4-5 52 2SW 2000 3 3 1 500 3 3 1 54 10 SE 450 3 3 2 200 3 2 1 4-6 50 8NW 5500 3 3 3 100 2 2 1 40 20NE 200 1 2 1 0 - - - 4-8 30 8NW 5800 2 2 3 200 2 2 0 4-10 40 25NW 9800 3 3 3 600 2 3 1 40 15NE 300 2 2 2 500 1 1 1 4-11 30 20NE 2000 2 2 3 300 1 2 1 36 8NE 1200 3 3 3 800 1 2 2 4-12 30 15NE 1500 2 2 3 500 3 2 2 39 2 ONE 150 2 2 2 200 1 2 1 4-13 47 8SW 100 1 1 1 0 - - - 60 4SE 1200 2 2 2 700 2 3 2 4-14 64 6SE 2400 1 2 2 8700 2 3 3 70 8S 500 1 2 1 5000 2 3 3 4-15 60 4S 3500 2 2 3 11200 3 3 3 4-16 61 10NE 1250 2 2 3 1000 1 2 1 4-17 66 8SE 3200 1 3 3 6000 3 3 3 58 30W 0 --- 700 2 2 2 4-18 46 30NW 3500 2 3 3 1500 2 3 2 40 20NW 100 1 1 2 0 --- 4-19 40 15N 8100 3 3 3 1500 1 2 2 47 5NE 1900 2 3 3 200 1 2 1 4-20 39 8NE 4000 3 3 3 0 --- 45 2 ONE 800 2 2 3 500 1 2 2 4-21 56 3E 200 1 2 3 200 1 2 1 4-22 56 20W 15300 1 3 3 1800 2 3 3 4-23 36 20NW 4100 0 3 3 2000 1 2 2 47 8NW 700 1 2 2 50 0 1 2 4-24 37 20NW 100 0 1 2 0 - - - 4-25 32 8NW 9100 1 3 3 0 --- 45 6SE 400 0 2 1 900 1 3 3 4-26 43 20E 3200 1 3 3 1000 2 2 3 4-27 39 15NW 8000 2 3 3 0 -- - 48 2NW 1000 1 2 3 200 2 2 2 4-28 39 0 11000 1 3 3 0 --- 55 0 1100 1 3 3 150 2 2 1 4-29 45 5SE 2000 0 3 3 3500 2 3 3 56 0 500 1 2 3 100 1 1 2 4-30 51 5SE 800 1 3 3 2500 2 2 3 64 8S 50 0 2 2 300 2 2 3 5-1 61 10SW 500 1 2 3 1100 3 2 3 70 2SE 100 0 1 2 0 - -- 5-2 50 15NW 1500 1 2 3 50~ 1 1 1 5-3 42 8NW 600 1 3 2 2000 2 3 3 52 5NW 500 1 1 2 50 1 1 1 5-4 43 10NE 3400 2 3 3 1000 2 3 2 5-5 43 15N 4600 2 3 3 2000 1 2 2 47 7E 900 0 2 2 0 - -- 5-6 40 12E 1000 1 2 2 150 0 1 1 52 10NE 1600 1 2 3 0 -- - 5-7 42 2 ONE 1000 1 3 3 0 - - - 5-8 43 4E 800 1 2 2 200 1 1 2 50 25NW 1500 1 2 3 0 --- 5-9 43 20NW 7500 1 3 3 500 2 2 2 5-10 42 25NW 7000 2 3 2 350 2 3 2 51 4E 1000 1 1 3 500 2 2 2 5-12 42 16NE 1600 1 2 3 200 1 2 1 5-13 45 10NE 1500 1 3 3 150 1 2 2 57 7E 1500 2 3 3 100 1 2 2 5-14 50 8SE 500 0 2 2 2200 2 3 3 59 2E 1000 2 2 3 800 1 2 1 5-15 55 4NW 1800 1 3 3 150 0 2 1 5-16 40 9NW 2500 2 3 3 300 1 2 1 59 10SW 200 0 2 2 100 1 2 1 5-17 47 10SW 50 0 2 1 400 2 3 1 5-18 51 10SW 100 1 2 2 150 1 2 2 67 20 SW 80 0 1 2 50 1 1 1 98
TABLE 2 (continued)
Morning Flights Evening Flights Date F° Wind North M F Y South M F Y F° Wind North M F Y South M F Y
5-19 60 18SW 100 1 1 3 200 1 3 1 5-22 52 10NE 50 1 1 2 50 1 1 1 5-23 55 15NE 10 1 0 1 100 1 0 2 5-24 53 10 SE 140 . 1 1 2 60 1 1 1 5-29 58 16NE 50 1 0 2 30 0 0 1 60 18NE 0 --- 20 1 0 1 6-2 60 5NW 80 2 0 2 15 0 0 1 6-6 75 2SE 0 --- 100 2 1 2 6-7. 68 5SE 250 2 0 2 0 --- 6-9 66 7E 100 2 0 2 20 1 0 1 6-12 80 10 SE 0 --- 200 2 1 2 6-15 67 6SW 170 1 0 2 75 0 0 2 6-22 68 6SE 25 0 0 1 150 2 1 1 6-23 68 2SW 1200 2 1 3 50 1 0 1 6-26 74 0 70 1 1 2 0 --- 6-28 68 15 SE 50 0 1 2 300 1 2 2 6-29 73 5NW 50 1 0 1 100 1 1 1 7-1 68 8NW 2500 3 3 2 80 1 2 2 7-3 69 6N 1200 3 2 2 100 1 1 1 7-7 72 9NE 200 1 2 2 250 1 1 2 7-8 70 6SE 1500 2 2 2 200 1 1 1 78 10E 500 2 2 2 400 2 0 1 7-9 70 2E 6500 3 2 3 500 1 1 2 7-10 70 0 1700 3 1 2 150 0 1 1 7-12 71 10NW 7000 3 3 3 200 0 1 2 68 25NW 50 1 0 2 100 1 0 1 7-13 65 12NW 3400 3 3 3 100 0 0 2 7-16 60 12NW 18000 3 2 3 200 1 1 2 7-17 64 3SE 12000 3 3 3 150 0 1 1 70 15SE 900 2 2 3 200 3 0 1 7-18 65 4SE 6000 2 3 3 150 0 1 2 68 5SW 25 1 1 2 50 2 1 1 7-20 65 0 6500 2 3 3 200 1 1 1 7-21 72 7NE 200 2 2 2 50 2 0 1 7-22 70 4SE 4500 2 3 3 150 0 2 2 7-24 75 15NW 2500 3 3 3 250 1 2 2 76 10NW 25 1 1 2 50 2 0 1 7-25 62 10NW 4000 3 3 3 200 2 2 3 7-26 68 10NW 5100 3 3 3 100 1 1 1 74 12 SW 50 2 1 1 100 3 0 1 7-27 72 12SW 10 0 1 1 300 3 2 1 7-29 72 0 7000 3 3 3 500 1 1 3 7-30 70 6SW 0 --- 200 3 1 2 7-31 67 3SE 2600 0 2 2 0 - -- 8-2 68 8SE 2200 1 2 2 50 0 0 2 8-3 68 6SW 1500 0 2 3 50 0 1 1 8-4 65 12NW 1200 1 3 3 0 --- 8-8 70 5NW 3600 1 2 3 100 0 1 1 8-11 58 15N 800 0 2 3 50 0 1 1 70 7NE 150 1 1 2 100 1 2 2 8-12 60 6NE 3000 1 3 3 50 0 1 2 8-14 55 4SW 3000 1 2 2 100 1 1 1 99
TABLE 2 (continued)
Morning Flights Evening Flights Date F° Wind North H F Y South M F Y F° Wind North M F Y South M F Y
8-15 63 4SW 2600 1 2 3 150 0 1 1 8-16 65 7SW 1500 0 3 3 120 1 1 2 8-20 63 8N 250 0 2 3 50 0 1 1 8-21 65 5NW 3500 1 3 3 300 0 2 2 8-22 62 10 NE 200 0 2 3 0 - -- 8-23 58 15NE 1200 1 3 3 100 0 1 2 8-24 62 15NE 1200 2 3 3 200 0 1 1 8-25 67 3SE 1400 0 2 3 500 1 2 3 8-28 74 4NW 0 -----250 2 2 3 8-29 55 5NW 1000 1 2 3 25 0 1 1 80 15NW 0 -----500 2 2 3 8-31 53 25NE 400 1 1 3 0 --- 9-2 52 7NW 800 1 2 3 0 --- 9-3 54 3E 600 0 2 3 0 --- 9-5 56 0 200 0 1 2 0 - -- 9-6 74 2NE 0 -----0 - - - 9-8 62 3SE 100 0 1 2 150 1 1 2 9-11 54 20SE 70 0 1 1 100 0 2 2 9-12 40 12 SE 20 1 1 1 160 0 1 2 9-13 50 8SE 50 0 1 1 1000 2 3 3 75 10 SE 0 -----0 --- 9-14 56 3SE 100 0 1 1 1800 2 3 3 9-15 50 10SE 0 --- 2000 2 3 3 9-17 60 3W 50 0 1 1 150 0 1 2 9-19 56 0 0 - -- 100 1 1 2 9-20 58 6SW 0 --- 150 1 1 2 9-21 66 15 SW 0 --- 100 2 1 2 9-22 50 20NW 0 --- 0 --- 9-23 58 10NW 0 -----100 2 0 1 9-25 50 5NW 0 --- 500 1 1 2 58 3NW 0 -----30 1 0 1 9-27 56 10NW 0 - - - 220 0 1 1 9-30 50 18SW 0 - -- 150 2 1 2 CO §5 io-2 60 6SE 1500 1 3 2 3200 3 3 3 76 0 ----- 100 1 0 2 10-3 58 5SW 2300 1 3 3 2200 3 3 3 10-4 65 10 SW 5800 2 3 3 6500 3 3 3 10-5 68 10NW 1200 1 3 2 1800 2 0 2 10-6 55 2 ONE 200 2 2 2 100 1 0 1 10-7 50 18NE 400 1 2 3 50 0 0 1 60 20NE 0 ----- 150 1 1 1 10-9 50 15NW 600 1 3 3 200 1 0 1 10-10 48 10 SW 2000 1 3 2 1000 2 1 2 10-11 40 20NW 600 0 2 3 5000 2 1 2 10-12 43 10NW 5D0 1 2 3 300 0 0 1 10-13 44 15 SW 350 0 2 2 1400 2 3 1 10-15 52 12SE 5000 1 3 2 9400 2 3 2 10-16 60 3SW 2000 0 2 2 300 1 2 2 10-18 49 25NW 0 --- 5000 1 2 2 100
TABLE 2 (continued)
Morning Flights Evening Flights Date F° Wind North M F Y South M F Y F° Wind North M F Y South M F Y
10-19 42 30NW 0 _. 2000 1 1 2 10-20 34 6SE 1400 1 3 3 1100 2 3 2 10-22 38 0 0 -- - 2000 0 2 1 10-23 45 6SE 6200 1 3 3 8500 2 3 3 10-24 46 8SE 500 1 3 3 2000 3 3 3 68 15SE 0 -- - 1000 3 2 3 10-25 47 25NW 150 1 2 3 50 1 1 1 10-26 45 20NW 0 - - - 8000 1 2 1 10-28 36 15NW 200 1 2 3 6000 3 2 2 10-29 33 15SE 40 0 1 1 2000 1 2 1 10-30 48' 8SE 100 0 1 2 3200 3 3 3 10-31 60 20NW 100 0 1 2 1300 2 3 2 11-1 58 6SE 10 0 1 1 50 2 2 1 11-2 60 5SW 25 0 1 1 1000 3 3 1 65 4S 0 -- - 100 3 3 1 11-3 46 3S 100 1 2 2 9000 3 2 2 48 8SW 0 -- - 150 3 2 1 11-4 36 20NW 0 - - - 12000 3 3 1 11-5 30 20NW 0 - -- 4500 3 3 1 40 20NW 20 1 0 1 1400 2 2 2 11-7 45 7NW 0 - - - 6000 2 3 1 11-8 23 10 SW 0 - - - 30000 3 3 2 11-9 45 20NW 0 - - - 0 - - - 45 8SW 0 --- 500 3 3 2 11-10 50 6SW 0 -- - 16000 3 2 1 11-11 50 15SW 0 - -- 2000 3 2 2 11-14 30 20 SW 0 - - - 1000 3 3 3 11-15 28 20NW 0 - -- 5000 3 2 3 26 8W 0 - - - 1500 3 2 2 11-16 23 10SW 0 -- - 3000 3 1 2 11-20 31 10NW 0 - - - 2000 3 1 2 11-25 34 8W 0 - - - 200 2 0 2 11-28 29 10NW 0 -- - 80 2 0 1 12-10 34 5SW 0 - - - 0 - --
Recognized sex-age proportions (M, adult male; F, female; Y, first- year or juvenile male): 1-few individuals observed; 2-moderate numbers observed; 3-many observed 1967 1966 p.May Apr. 176 70 2 0 6 8 3 m 1 4 13 145 18 11 0 0 0 0 1 June 0 - 954 uyAug. July 250 35 62 19 23 26 222 22 37 0 5 9 4 5 8 10 9 28 6 RESIDENT FEMALES - 1966 AND 1967 AND 1966 - FEMALES RESIDENT 862 9 171 497 6 24 167 109 43 44 68 71 53 55 11 27 ISLAND BANDING PROGRAM BANDING ISLAND Sept. 47 37 29 75 63 212 22 12 5 9 TABLE 3 TABLE 978 Oct. 88 20 11
0 1 Birds Staying 9-15 Days 9-15 Staying Birds 1 0 5 0 0 "Residents" (Over 16Days) (Over "Residents" 0 0 - Nov. 167 Total Banded Total 167
20 3 3 wm 2 Birds Staying 2-8 Days 2-8 Staying Birds 2 Recovered Total 8 vrg "eiet ty (Days) Stay "Resident" Average vrg Rsdn"Sa (Days) Stay "Resident" Average Total Banded Total Total Recovered Total Birds Staying 9-15 Days 9-15 Staying Birds "Residents” (Over 16Days) (Over "Residents” Birds Staying 2-8 Days 2-8 Staying Birds Juvenile Adult p. a Jn Jl Ag Sp. c. Nov. Oct. Sept. Aug. July June May Apr. 4 4 143 144 343 361 107 221 52 834 28 93 19 425 22 14 23 928 29 3 7 RESIDENT MALES - 1966 AND 1967 AND 1966 - MALES RESIDENT 773 283 045 80 65 2 2 2 ISLAM) BANDING PROGRAM BANDING ISLAM) 2 1351 326 1 6. 76 360. . 312 34 32 14 36 .5 . 60 63 29 14 4 7 TABLE 4 TABLE 319 820 58 27 028 20 716 27 25
8 8 197 111
43 24 7 3 6 vrg "eiet Sa (Days) Stay "Resident" Average Total Banded Total Total Banded Total Birds Staying 2-8 Days 2-8 Staying Birds Recovered Total vrg "eiet Sa (Days) Stay "Resident" Average Days 9-15 Staying Birds Recovered Total Days 9-15 Staying Birds 1966 Birds Staying 2-8 Days 2-8 Staying Birds "Residents" (Over 16 Days)16 (Over "Residents" Rsdns (vr 16Days) (Over "Residents"
o N> TABLE 4 (continued)
Apr. May June July Aug. Sept. Oct. Nov. 1967
120 17 49 1051 264 44 75 40 Total Banded
40 11 13 119 76 28 18 11 Total Recovered
10 1 1 64 36 9 5 1 Birds Staying 2-8 Days
14 2 1 19 16 3 2 1 Birds Staying 9-15 Days
2 6 ' 5 16 17 7 10 4 "Residents11 (Over 16 Days)
47 39 43 31 27 21 30 20 Average "Resident" Stay (Days)
0) 350 106 198 1490 1736 179 305 153 Total Banded •h a <0 60 30 37 268 807 252 114 58 Total Recovered § 21 5 6 85 298 59 23 25 Birds Staying 2-8 Days
W 9 4 3 49 171 . 54 21 8 Birds Staying 9-15 Days £ 1 •u to 8 10 10 63 261 66 23 14 "Residents" (Over 16 Days) S-i •H 29 43 33 32 29 28 28 23 Average "Resident1- Stay (Days) TABLE 5 ISLAND BANDING PROGRAM: SUMMER AND FALL TRANSIENTS 1966 AND 1967
June July Aug. Sept. Oct. Nov.
MM 41-9 110-3 25-1 7-3 MM 1966 Juveniles-Adults Leaving 3-4 58-10 86-2 22-0 MM MM 1967 For Over 30 Days
60 49 39 33 MM' 1966 Mean Absence Before CQ 83 54 48 45 — MM 1967 Returning (Days) W >4 -- MM 11-5 55-1 103-6 13-4 1966 Juveniles-Adults Returning << MM — 13-5 83-6 60-4 16-1 1967 After Over 30 Days %
MM MM 38 41 56 52 1966 Mean Absence Before
-• — 36 45 64 66 1967 Returning (Days)
— 10 26 —— — 1966 Females Leaving For — 11 13 M M MM -- 1967 Over 30 Days (0 __ 50 43 MM MM MM 1966 Mean Absence Before w MM 36 38 — MM — 1967 Returning (Days) >4 < M M -- 4 16 16 MM 1966 Females Returning After A MM MM 11 8 5 MM 1967 Over 30 Days w Pm MM M M 31 40 54 MM 1966 Mean Absence Before MM 30 31 62 1967 Returning (Days) TABLE 6 ISLAND BANDING PROGRAM MAJOR REPEATING GROUPS
Number of Birds Present in Islands (between) Next Recorded in Islands (between)
13 juvenile males July 8 & August 28, 1966 (3 R) April 13 & June 19, 1967 2 adult males July 7 & 9, 1966 June 19 & 25, 1967 25 juvenile males July 14 & August 15, 1967 April 1 & 29, 1968(3 R)
13 juvenile males July 7 & August 30, 1966 (5 R*) June 12 & July 23, 1967 4 adult males July 7 & 30, 1966 June 19 & July 7, 1967 3 females July 8 & August 21, 1966 (1 R) June 26 & July 14, 1967
22 juvenile males September 2 & October 24, 1966 April 13 & May 10, 1967 (5 R) 11 adult males September 30 & November 3, 1966 April 13 & 28, 1967 (2 R) 6 females August 1 & October 12, 1966 April 17 & May 18, 1967
3 adult males September 23 & October 26; 1967 (1 R)April 1, 1968 (1 R) 2 juvenile males September 23 & October 26, 1967 (2 R)April 1 & 29, 1968 (1 R)
12 juvenile males. September 14 & October 14, 1966 (4 R)July 8 & 20, 1967 2 adult males October 30 & November 3, 1966 July 18 & August 4, 1967
7 juvenile males September 1 & October 3, 1966 (4 R) August 8 & September 15, 1967 4 adult males September 24 & October 30, 1966 September 23 & October 17, 1967 1 female November 3, 1966 November 7, 1967 TABLE 6 (continued)
Number of Birds Present in Islands (between) Next Recorded in Islands (between)
20 first-year males March 31 & May 10, 1967 (all R) May 25 & July 17, 1967 13 adult males April 13 & May 18, 1967 (all R) June 12 & July 14, 1967 2 females April 22 & May 18, 1967 (all R) June 26 & July 19, 1967
7 adult males April 17 & June 21, 1967 (4 R) September 15 & November 7, 1967 (2 R) 3 first-year males April 22 & July 10, 1967 (all R) September 15 & October 31, 1967 (1 R)
8 first-year males April 17 & June 28, 1967 (6 R) April 1 & 15, 1968 (2 R) 12 adult males April 8 & June 21, 1967 (8 R) March 27 & April 29, 1968 (5 R) 1 female April 22 & June 26, 1967 (R). April 10, 1968
*Resident Birds TABLE 7 ISLAM) BANDING PROGRAM RELATED BAND RECOVERIES
Band Number & Age Location I DateI Location II Date II
562-84721 juvenile) Paincourt, Ontario Aug. 10, 1966 Bass Islands Oct. 20, 1966 712-21248 juvenile) Paincourt, Ontario Aug. 24, 1966 Bass Islands Oct. 24, 1966
67-145457 female) South of Sandusky Bay July 21, 1966 Ottawa Refuge Aug. 21, 1966 682-94196 juvenile) South of Sandusky Bay Aug. 10, 1966 Ottawa Refuge Sept . 5, 1966
682-58558 juvenile) South of Sandusky Bay July 13, 1966 Bass Islands Aug. 25, 1966 682-94004 juvenile) South of Sandusky Bay July 22, 1966 Bass Islands Aug. 14, 1966 682-53230 juvenile) Sputh of Sandusky Bay July 22, 1966 Bass Islands Aug. 17, 1966 682-94406 juvenile) South of Sandusky Bay Aug. 18, 1966 Bass Islands Oct. 14, 1966 712-40898 juvenile) South of Sandusky Bay Sept 20 , 1966 Bass Islands Oct. 20, 1966
682-95549 juvenile) Bass Islands July 30, 1966 South of Sandusky Bay Aug. 27, 1966 682-97605 juvenile) Bass Islands Aug. 31, 1966 South of Sandusky Bay Oct. 1, 1966 682-97946 juvenile) Bass Islands Oct. 17, 1966 South of Sandusky Bay Oct. 26, 1966 682-98290; juvenile) Bass Islands July 20, 1967 South of Sandusky Bay Oct. 23, 1967
682-94939 juvenile) Bass Islands Sept 30 , 1966 Kingsville, Ontario May 13, 1967 682-96902 juvenile) Bass Islands Oct. 17, 1966 Kingsville, Ontario May 13, 1967
682-97272 juvenile) Bass Islands July 13, 1967 Kingsville, Ontario Aug. , 1967
712-21031 juvenile) Paincourt, Ontario Aug. 24, 1966 Bass Islands Apr. 8, 1967
712-40124 juvenile) Ottawa Refuge Sept 5, 1966 Bass Islands Oct. 24, 1966 712-49290 juvenile) Ottawa Refuge Aug. 16, 1967 Bass Islands Oct. 31, 1967 TABLE 7 (continued)
Band Number & Age Location I Date I Location II Date II
682-58988 (first-year) South of Sandusky Bay Mar. 29, 1966 South of Sandusky Bay Mar. 24, 1967 682-58501 (first-year) South of Sandusky Bay May 28, 1966 South of Sandusky Bay Mar. 24, 1967 682-89730 (adult) South of Sandusky Bay May 3, 1966 South of Sandusky Bay Apr. 6, 1967 682-89652 (first-year) South of Sandusky Bay Apr. 11, 1966 South of Sandusky Bay Apr. 13, 1967 67-145421 (first-year) South of Sandusky Bay May 17, 1966 South of Sandusky Bay Apr. 20, 1967
692-27076 (juvenile) Columbus, Ohio Nov. 28, 1964 Ottawa Refuge July 16, 1966 712-16873 (juvenile) Columbus, Ohio Nov. 8, 1965 Bass Islands Oct. 17, 1966 662-79129 (juvenile) Columbus, Ohio Nov. 13, 1965 Bass Islands Oct. 6, 1967 662-79308 (first-year) Columbus, Ohio Mar. 6, 1966 Bass Islands Oct. 6, 1967 109
MAP I. THE WESTERN LAKE ERIE BASIN
Leamington
tester
Pa lee ' Island North Bass Is
Middle Island South Bass Is Catawba folleys Island
vCedar Point Sandusky
/Huron, River Fremont OHIO 10 Mi Lakeside y t a s t x ^ (^ Marblehead Harbor
Cedar Point H.Y.C. >. Railroad \ Bridge Sandusky Bay Ill
GRAPH I SPRING FLIGHTS AT CATAWBA (Three-Day Totals)
— 1966 ------1967
10 V -\
March April 20 23 26 r ~ \ m IQ
?20 22 112
ORAPH II, SOMMER FLIGHTS AT CATAWBA (Three-Day Totals) —:------1966 ------1967
Jane August 25 28 31 ___ Thousands of Redwings South Thousands of Redwings North yyUUiMMNNlOH H M H M H M M J O Oft O
Afts
to TO M 0\ IH vnTO • o to CD 113 GRAPH 17,
Mean Dally Ambers of Redwings Banded In The Lake Islands July Through November 1?66 -Adult Males * Juvenile Males ’ Females 95 90 85 80 75 70 65 60 55 50 U5 1*0 35 30 25
20 Dally Banded Redwings Mean 15
5 8 11 lit 17 2023 25 29 1 U 7 10 13 36192225 28 31 3 6 9 1235 18 21 2b27 30 3 6. 9 12 $18 2121*2730 2 5 8 U S * 17 2323 26 July August September October November 1966 GRAPH T, Mean Daily Numbers of Redwings Sanded In The Lake Islands Spring 1967 Adult Hales First-Tear Males Females
April 115 1967 Mean Redwings Banded Daily 125 315 120 105 110 . 2C 100
3 6 91215 182L2ii27 91215 30 6 3 3 June 6 9 121518ZL2US? 302 5 8 UlltH 2023* 29 1 U 7 D 1316192225 28 1 1316192225 D 7 U 29 1 2023* UlltH 8 5 302 9 121518ZL2US? August Mean Mean Daily Hbmbers of Redwings Balidad In TheLake Islands Summer 1967 GRAPH VI, Females Juvenile Males — — Adult Males — First-Tear Males — September ORAPH vn, Mean Dally Humbers of Redwings Banded In The Lake Islands Fall 1967 Adult Males Juvenile Males — -- Females
• 13
2 It 6 8 1012 3l|l6 IB 2022 & 2628 30 2 1( 6 8 10 12U» 161820 223(26 3 33 1 3 5 9 1113153719 21 September October
1967 7 1 1 I
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