COMPARATIVE STUDY OF BREEDING ECOLOGY AND
TIMING IN PLANKTON-FEEDING ALCIDS
(CYCHLORRHYNCHUS AND AETHIA SPP.)
ON ST. LAWRENCE ISLAND, ALASKA
BY
SPENCER GEORGE SEALY
B.Sc, University of Alberta, 1964
A THESIS SUBMITTED IN PARTIAL FULFILMENT OF
THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE
in the Department
of
Zoology
We accept this thesis as conforming to the
required standard
THE UNIVERSITY OF BRITISH COLUMBIA
April, 1968 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the
Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his represen•
tatives. It is understood that copying or publication of this thesis for
financial gain shall not be allowed without my written permission.
Department nf
The University of British Columbia Vancouver 8, Canada
Date ABSTRACT
A comparative study of breeding ecology in Parakeet
Auklets (Cychlorrhynchus psittacula (Pallas)), Crested
Auklets (Aethia cristatella (Pallas)), and Least Auklets
(A. pusilla (Pallas)) was conducted on St. Lawrence
Island, Alaska, in 1966 and 1967. Emphasis was placed upon the climatic conditions which prevailed throughout the breeding seasons and their effects on timing of breeding in auklets.
The pre-egg stage, egg-laying and incubation, hatching, growth of young, and departure of chicks were studied in both seasons; 1966 was a late year and
1967 was an early year.
It was found that (1) Parakeet Auklets appear to have a more extensive migration than Aethia spp. ,
(2) arrival of adults back on the breeding grounds in
spring occurs at approximately mid-May each year, (3) the pre-egg stage is prolonged but the post-breeding dispersal of adults and young from the nesting slope
is rapid, (4) breeding does not take place at the same
time each year, (5) Cychlorrhynchus breeds a few days
later than.Aethia spp., (6) a change in diet accompanies
the onset of the chick-rearing period in Aethia spp. but not in Cych1orrhynchus, (7) patterns and rates of growth of A. pusilla chicks and possibly chicks of
Cychlorrhynchus and A. cristatella differ according to time of hatching, (8) chicks of these auklets are well- adapted to early life, (9) predation upon auklets is low in the Sevuokuk colony, and (10) molt of adults overlaps the breeding effort in Aethia spp. but not in Cychlorrhynchus.
Ecological and behavioral specializations in the annual cycles of these auklets revealed close synchronization and shortening of breeding events necessary for breeding in the short Arctic summer.
It appears that these auklets are faced with two problems in timing their breeding cycles. Breeding must take place within a period which is largely dictated by climate and they must make best use of the food supply. iii
TABLE OF CONTENTS
Page
ABSTRACT i
TABLE OF CONTENTS iii
LIST OF FIGURES vi
LIST OF TABLES X
ACKNOWLEDGEMENTS xiii
INTRODUCTION • 1
A. Scope of Study and Previous Work 1
B. Study Area •••• • 4
C. Methods 16
D. Distribution of North Bering Sea Auklets 21
E. Migration, Dispersal and Winter Distribution of
North Bering Sea Auklets . 22
CHAPTER I. The pre-egg Stage 26
A. Arrival of auklets at the Breeding Colony 26
B. Effect of Snow Cover on the Onset of Nesting 28
C. Colony Structure 35
a. Pair-bond in auklets 36
b. Nest-site tenacity 37
c. Territoriality 39
d. Non-breeders 40
D. Copulation 40 iv
CHAPTER II. The Egg Stage 44
A. The Nests of Parakeet, Crested and Least Auklets ... 44
a. Description of the nesting environment 44
b. Segregation on the nesting slope 48
B. Egg-laying in Auklets 59
a. The seasonal pattern of egg-laying 59
b. The daily pattern of egg-laying 67
C. The Clutch in Parakeet, Crested and Least Auklets .. 68
a. Description of the eggs 68
b. Clutch size 75
c. Replacement of lost or destroyed eggs 76
D. Incubation in Parakeet, Crested and Least Auklets .. 80
a. Incubation periods in auklets . 80
b. Incubation temperatures in Parakeet, Crested
and Least auklets 83
1. Nest temperatures 83
2. Brood patches and brood patch temperatures . 87
c. Incubation rhythm in Parakeet, Crested and
Least auklets 91
CHAPTER III. The Chick Stage 94
A. The Nestling Period in Auklets 94
B. Feeding Habits of Auklets 97
a. Prey species 97
C. Growth of Chicks 102
D. Thermoregulation 122 V
a. Body temperatures and thermoregulation in
auklet chicks 124
E. Fledging of Chicks 136
CHAPTER IV. Predation 144
CHAPTER V. Molt of Adults and Juveniles 152
CHAPTER VI. Timing of the Breeding Cycles in North Bering
Sea Auklets • 157
A. Ultimate Factors 158
a. Nesting sites 158
b. Food and its availability 162
B. Proximate Factors 166
a. Temperature.during the pre-egg stage 166
b. Nest-sites 167
c. Day-length and internal factors 167
1. The testis cycle in adult male auklets 168
C. Additional Adaptations for Timing in Auklets 171
D. Summary of Timing 175
SUMMARY 177
REFERENCES 182
APPENDIX I 193 LIST OF FIGURES
Figure Facing Page
1 Outline map of St. Lawrence Island, Alaska,
showing locations of the Sevuokuk and Kongkok
auklet colonies, and the village of Gambell. 6
2 Map of Bering Sea and other waters inhabited
by Parakeet, Crested, and Least auklets during
winter and breeding seasons. 7
3 • Map of Sevuokuk Mountain and surrounding waters. 8
4 Pattern of snow-melt on Sevuokuk Mountain in
1966 and 1967. 29
5 Snow-cover on west slope of Sevuokuk Mountain,
St. Lawrence Island, 2 June 1967. 30
6 Sevuokuk Mountain, northeast slope, 23 June 1967. 30
7 Crested and Least auklets settled on rocks and
snow on the northeast slope of Sevuokuk Mountain,
25 June 1967. 32
8 Auklets (Aethia spp.) "sitting" on the snow at
the brow of the northeast slope of Sevuokuk
Mountain. 32
9 Cross^section of main nest types of Parakeet
Auklets on Sevuokuk Mountain, St. Lawrence Island. 49
10 Cross-sections of main nest types of Crested
Auklets on Sevuokuk Mountain, St. Lawrence Island. 50 Cross-sections of main nest types of Least
Auklets on Sevuokuk Mountain, St. Lawrence
Island.
Generalized model showing the segregation between Aethia cristatella and A. pusilla on the nesting slopes according to average rock diameter. Brom Bedard (1967:123).
Egg-laying in Parakeet Auklets on Sevuokuk
Mountain, St. Lawrence Island.
Egg-laying in Crested Auklets on Sevuokuk
Mountain, St. Lawrence Island.
Egg-laying in Least Auklets on Sevuokuk
Mountain, St. Lawrence Island.
Mean maximum and minimum air temperatures in a nest-site of A. cristatella during the latter half of the breeding season, 1966.
Mean maximum and minimum ambient temperatures for the same period are also included.
Relative importance (in volume) of various prey items of various size categories in the early summer diet of Aethia pusilla and
A. cristatella (food in gullets). From
Bedard (1967:46). Relative importance (in volume) of various prey- types of various size categories in the food brought to the chick during August and September
(food in neck-pouches). From Bedard (1967:47).
Growth of Parakeet Auklets.
Growth,of Crested and Least auklets.
Growth of the outer primary in Parakeet, Crested and Least auklets.
Growth in Least Auklets in relation to their hatching dates in 1966.
Growth curves of A. pusilla chick (#169) hatched 29 July 1966 and A. pusilla (#159) hatched 5 August 1966.
Body temperatures in nestling Parakeet, Crested and Least auklets after exposure to ambient temperatures about 11°C for 40 minutes.
Responses of Parakeet Auklet of ages 0 day to 6 days to ambient temperatures.
Responses of Crested Auklet of ages 0 day to
3 days to ambient temperatures.
Responses of Least Auklet of ages 0 day to 6 days to ambient temperatures.
Parakeet Auklet chick, 29 days old, 1 September
1967. Showing wound on its back.
Least Auklet chick, 28 days old, 31 August 1967.
Showing mutilated condition of left eye. IX
30 A generalized summary of breeding activities
and molt in Parakeet Auklets. 153
31 A generalized summary of breeding activities
and molt in Crested Auklets. 154
32 A generalized summary of breeding activities
and molt in Least Auklets. 155
33 Northeast slope of Sevuokuk Mountain showing
accumulation of snow on brow of Mountain, 5 June
1967. 161
34 Close-up view of brow of northeast slope of
Sevuokuk Mountain showing accumulation of snow,
5 June 1967. 161
35 Seasonal change in testis size (weight of left
testis) of Least Auklets in 1966. 169
36 Seasonal change in testis size (weight of left
testis) of "snow-sitting" and "rock-sitting"
Least Auklets in 1967. 170 X
LIST OF TABLES
Table Facing Page
1 Average temperatures at Gambell, Alaska, from 1943
through to 1952. 10
2 Monthly and seasonal snowfall at Gambell, Alaska
from 1942-1943 through to 195 2. 11
3 Air temperatures recorded at 8m contour and at
120m contour on the northeast slope of Sevuokuk
Mountain, 1966. 13
4 Air temperatures recorded at 8m contour and at
120m contour on the northeast slope of Sevuokuk
Mountain, 1967. 14
5 Arrival dates in May of auklets on St. Lawrence
Island during 1964 to 1967 seasons. 27
6 Banding and subsequent observations of A.
cristatella and A. pusilla in 1966 and 1967. 34
7 Nest perimaters, perch to nest-site distances and
time involved from landing on perch to entering
nest-site in auklets. 56
8 Egg-laying in Parakeet, Crested and Least auklets. 66
9 Dimensions of Parakeet Auklet eggs. 69
10 Dimensions of Crested and Least auklet eggs. 70
11 Weights of fresh and pipped eggs in eight species
of alcids. 72 Egg-weight in relation to body-weight in some alcids.
Period from laying egg until the chick is free o the shell in C. psittacula, A. cristatella and A pusilla.
Temperatures inside the nest-site of Aethia psuilla.
Temperatures of the fully developed brood patch compared to the body temperatures in auklets.
Temperatures of the fully developed brood patch compared to body temperatures in some alcids.
Nestling periods of Parakeet, Crested and Least auklets.
Growth in Parakeet Auklets, St. Lawrence Island,
1967.
Growth in the Crested and Least auklets, St.
Lawrence Island.
Growth in Least Auklets on St. Lawrence Island,
Alaska.
Body weights and measurements of young auklets at hatching and at time of sea-going.
Average daily instantaneous growth rates in
Parakeet, Crested and Least auklets.
Nestling periods of Least Auklets in relation to their hatching dates, 1966. xii
24 Esophageal temperatures in Cychlorrhynchus
psittacula, Aethia cristatella and A. pusilla
chicks in relation to age and burrow temperature. 125
25 Esophageal temperatures of Cychlorrhynchus
psittacula, Aethia cristatella and A. pusilla
during thermoregulation experiments. 126
26 Subcutaneous fat deposition in known-age chicks
of Parakeet, Crested and Least auklets from
hatching to sea-going. 134
27 Summary of relative chick body weights and
measurements to adult body weights and measurements
in auklets. 137
28 Weights and wing area ratios of auklets. 139
29 Sea-going dates of Parakeet, Crested and Least
auklets, St. Lawrence Island, 1966 and 1967. 143 ACKNOWLEDGEMENTS
I am grateful to Dr. M.D.F. Udvardy who supervised the initial stages of this work and provided financial support from his National Research Council of Canada grant.
I should like to express my sincere appreciation to Dr. F.G. Cooch, Dean I. McT. Cowan, Dr. H.D. Fisher,
Dr. W.S. Hoar, Dr. J.M. Taylor and Dr. M.D.F. Udvardy for their constructive criticism of the thesis.
Special thanks are extended to Dr. Jean Bedard who provided invaluable assistance and advice at all stages of this study. His constant encouragement during the planning stage, field-work and writing is much appreciated. He gave free access to unpublished data
in his files and critically read the manuscript. His unstinting help is most gratefully acknowledged.
While in the field, I was helped on numerous occasions by the Eskimos of Gambell. I benefited from discussions, scientific or otherwise, with Mr. Steve
Young.
Dr. V.J. Krajina and Dr. W. Schofield kindly
identified forbs and mosses collected on the nesting
slopes. I benefited from a discussion of growth with
Dr. H.C. Nordan. xiv
Much help, advice, and encouragement were provided by M. Aleksiuk, R.D. King, and K.W. Reid, and I wish to acknowledge their assistance and that of all others who aided in the preparation of this thesis. XV
Adult Parakeet Auklets on Sevuokuk Mountain, St. Lawrence
Island, Alaska.
Adult Crested Auklet (left) and adult Least Auklet (right)
on Sevuokuk Mountain, St. Lawrence Island, Alaska.
INTRODUCTION
A. Scope of Study and Previous Work
The majority of accurately-timed annual zoological events are closely connected with reproduction. If adult individuals over a wide area mature simultaneously, an adequate supply of mates of both sexes is likely to be ensured; and if maturation is further associated with congregating or mixing of individuals from adjacent populations it can be expected to produce a suitable measure of outbreeding (Wynne-Edwards, 1962). As in higher animals in general, reproduction in birds is intermittent. Some degree of intermittency is imposed by the temporal requirements of the reproductive processes
(Farner, 1967). More significant, however, in the evolution of intermittent reproductive function is the adaptive significance of control systems that so regulate reproduction that young are produced during the season in which the probability of survival tends to be maximal and stress on adults tends to be minimal (Aschoff, 1955; Farner,
1961, 1964; Immelmann, 1963; and others). Among species that inhabit the distinctly annually periodic environments of the mid and high latitudes reproductive activity
is characteristically annual and the reproductive seasons are clearly defined (Aschoff, 1955; Farner, 1959, 1961, 2
1964; Lack, 1950; and others). In discussing the factors that control breeding seasons it is helpful to distinguish between ultimate and proximate factors, as originally pointed out by Baker (1938) and restated by Snow and
Snow (1964). Ultimate factors are those which make breeding possible, or more likely to succeed, at one time of the year rather than another, and include especially,
for birds, weather and the food supply for the young.
These are the factors that ultimately determine at what time of the year breeding takes place. Proximate factors are those factors in the changing environment to which
the organism responds, and which act as timers of breeding
in the physiological sense. They need be themselves of no direct significance for breeding. The shorter
the period between the beginning of breeding activities
and the production of young, the more likely it is that ultimate and proximate factors will be closely related.
After spending six weeks in the Perry River
region, Northwest Territories, in 1965, I became more
aware of the sometimes very harsh conditions faced by
animals which breed in the Arctic and realized how important
it is for them to time their breeding events precisely
if their survival is to be ensured. It was my intention
to work with colonially-nesting sea-birds in a family
having a diverse breeding range which might give some 3
insight into adaptations for arctic-breeding shown by these birds. When I learned that Jean Bedard was completing a study on ecological segregation in Parakeet, Crested, and Least auklets on St. Lawrence Island, Alaska, and that a permanent field camp had been established there,
I found all my requirements satisfied. The occurrence of three closely related alcid species provided excellent material for comparative study which would supplement recent studies of other Pacific alcids (see Drent, 1961;
1965; Payne, 1965; Richardson, 1961; Thoresen, 1964; and others). Bedard's attention was directed primarily toward the social structure of these species during the pre-egg stage, their feeding ecology and segregation on the nesting slope. Only sporadic and miscellaneous observations on the breeding biology of these auklets had appeared in the literature prior to Bedard's work.
My programme was, therefore, to undertake a comparative study of the breeding ecology of Parakeet, Crested and
Least auklets emphasizing the onset, duration and termination of the pre-egg, egg-laying and incubation, and chick stages, and to: (1) study the climatic conditions throughout the breeding season and their effects if any on timing in auklets, and (2) elucidate the apparent adaptive significance of the timing which exists. Before describing the study area and methods, a word on the systematic position of the North Pacific plankton-feeding auklets is necessary. 4
The systematic position of the plankton-feeding alcids has not been studied in detail. It is apparent
from a perusal of the literature pertaining to the
Alcidae that much confusion existed during its early . classification (Coues, 1868; Shufeldt, 1891; and others), and the situation does not appear to be completely settled today (see Gysels and Rabaey, 1964). In his monograph on the Alcidae, Coues (1868) lists, up to 1868, no less
than five different generic names applied to the present- day Cychlorrhynchus. Using the type, by monotypy,
Alca psittacula Pallas (1769), Kaup described the present genus, Cychlorrhynchus Kaup (1829), while the original
specific name was retained (A.O.U. Check-list, 1957:
254). Similar confusion prevailed during the initial description of Aethia cristatella and A. pusilla.
Using the type, again by monotypy, Alca cr istatella
Pallas (1769), Merrem described the present genus,
Aethia Merrem (1788), while the original specific name
of the Crested Auklet has also been retained. A. pusilla
(Pallas) was originally described as Uria pusilla Pallas
(1811). Thus, the names, Parakeet Auklet, Cychlorrhynchus
psittacula (Pallas), Crested Auklet, Aethia cristatella
(Pallas), and Least Auklet, Aethia pusilla (Pallas), will be utilized throughout this thesis.
B. Study Area
The field-work was carried out on St. Lawrence 5
Island (figure 1) in the north-central sector of the
Bering Sea (figure 2); the study itself was limited to the colony on Sevuokuk Mountain and waters surrounding the Northwest Cape area of the Island (figure 3). The
Island, an arctic land mass of about 2,000 square miles, lies about 200 miles directly south of the Bering Strait.
The Northwest Cape is about 40 miles from the nearest
Siberian point, Chaplino, and the Northeast Cape is about 130 miles from the Alaskan Seward Peninsula.
The physiography of St. Lawrence Island has been described by Fay and Cade (1959) and supplemented by Thompson
(1967) for Northeast Cape and the Punuk Islands. The detailed description of the nesting slopes in the study area on Sevuokuk Mountain will be presented in Chapter II.
The climatic conditions of the Island have an important influence on auklets' breeding and will be demonstrated later in this thesis; however, it is necessary at this point to summarize available climatic data.
The Island has a typical arctic maritime climate even though it is about. 250 miles south of the Arctic Circle.
The following summary from the United States Weather-
Bureau (1953) depicts the windy, stormy and foggy nature of Gambell's climate (summary of data collected from 1943 to 1952): .
Temperatures at Gambell are moderately low, the mean yearly temperature being 24.2°F. Extreme low temperatures are rare, due in part to high surface winds, high frequency occurrence Outline map of St. Lawrence Island, Alaska, showing locations of the Sevuokuk and Kongkok auklet colonies, and the village of Gambell.
Legend for Figure 2
Map of the Bering Sea and other waters inhabited by Parakeet, Crested and Least auklets during winter and breeding seasons. 176 ° 8
Legend for Figure 3
Map of Sevuokuk Mountain and surrounding waters.
Solid arrow indicates northeast slope where nesting studies
were conducted; open arrow indicates location where birds
were collected on west slope. Contour levels are in feet.
Inset shows Sevuokuk Mountain in relation to the remainder
of the Island.
of low cloud, high average sky cover and proximity to the Bering Sea. The record low temperature of -30 occurred in February 1947. The all time high is 65 established in July of 1952. Mean yearly precipitation is fairly evenly distributed to all months. Precipitation occurs on approximately 300 days of each year. Total snowfall is not representative of depth of snow on ground as the greater part of snowfall is blown from the ground as prevailing winds are from seaward, NE, very little of the displaced snow is replaced. Mean average wind veolcities are high and storms with strong winds may be expected in each month. The all time high velocity recorded at this station is 100 mph from the south, which occurred in October, 1946. Average sky cover, sunrise to sunset, is high with approximately 32 days per year with clear sky.
Table 1 shows the average temperature and table
2 presents snowfall at Gambell from 1943 to 1952 (data from U.S. Weather Bureau, 1953). The climate during the auklets' breeding season, about 20 May to 10 September, is characterized by prevailing winds from the south and southwest often accompanied by fog and rain. From
April to November the Island's weather is affected by the northern edge of a major low pressure system, centered
in the Aleutian Islands (U.S. Navy, 1956). A primary track of storm centers., originating in the North Pacific
Ocean and southern Bering Sea, passes over or near the
Island during July and August resulting in high winds and intermittent rains which are believed by Fay and
Cade (1959:77) "to be prominent factors affecting brood
survival of many of the breeding birds," a point which 10
Legend for Table 1
Average temperatures at Gambell, Alaska, from 1943
through to 1952. Data from United States Weather Bureau
(1953) . Temperatures converted to °C. TABLE 1
Year Jan. Feb. Mar. Apr. May June Ju ly Aug. Sept. Oct. Nov. Dec. Annua!
1943 -15. 6 -17.4 -11. 3 -8.0 0.4 4. 3 7.8 7.4 3.8 0.9 -2.3 -13.4 -3.6
1 1944 -19.1 -14. 7 -15. 1 -11.4 -1. 7 2.8 6.4 6. 7 4.5 -0.4 -7.8 -12. 2 -5.6 1945 -15. 2 -18. 1 -20. 2 -6. 2 -2.6 2.3 8. 7 7.0 5.2 -2.3 -7.7 -14. 0 -5.3
1946 -14.6 -21.5 -18.6 -12.4 -2.3 3.0 6.4 5.7 3.8 0.2 -4. 3 -13. 8 -5.7 1947 -17. 6 -13.3 -16.8 -7.7 -0.4 2.6 6. 3 6.5 3.1 -1.5 -7.1 -16.5 -5.2
1948 -18. 3 -14.0 -13.0 -2.3 -1. 8 4.3 6.5 6.3 3.5 -1.8 -7.3 -11. 2 -4.1
1949 -12. 7 -14.6 -10. 6 -10. 2 -3.1 1.5 6.1 8.1 4. 7 1.3 -4. 1 -9.5 -3.6 1950 -5.0 -11. 7 -11.6 -8. 1 -2.8 2.6 7.0 8.0 4. 7 1.6 -6. 1 -6. 8 -2.2
1951 -17.5 -17. 7 -15.8 -8.3 -1.0 3.3 6.8 6.9 3.3 0.3 -3.3 -7.2 -4.2
1952 -13.3 -17. 8 -15. 3 -9.3 -2.2 2. 1 5.8 6.9 4. 9 0.8 -2.1 -12.0 -4. 3 11
Legend for Table 2
Monthly and seasonal snowfall at Gambell, Alaska,
from 1942-43 through to 1952. Data from United States
Weather Bureau (1953). Depth of snowfall converted to
cm. TABLE 2
Season Ju ly Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June Total
1942-43 „, 6.0 15.5 17. 6 10. 3 7.8 0. 0 1943-44 0. 0 0. 0 24.0 .16.7 13. 3 14.5 43.5 11. 3 20. 6 4. 8 T 148. 8 1944-45 0.0 T T 5.3 13.0 33. 3 22. 8 33. 8 6.5 7.8 3.0 2.0 127. 3 1945-46 0. 0 0.0 T 37.8 24.0 9.0 16. 3 5.3 4.3 21.5 6. 0 T 124. 0 1946-47 T T T 15. 3 7.3 15.0 12.0 16.5 1.5 2.5 6.0 0.0 76.0
1947-48 0.0 T 0.3 18. 8 9.5 29. 0 16. 3 12.5 43.5 3.3 0. 25 T 133. 3 1948-49 0.0 0.0 T 3.3 13.5 16. 3 13.5 11. 3 17.5 8. 3 16. 0 5.0 100. 0 1949-50 0. 0 T T 18. 0 45. 3 44. 0 80. 3 14. 8 121.3 137. 8 14. 3 T 475.5 1950-51 0.0 0.0 T 4.5 27.0 78. 3 10.5 121.5 42. 8 49. 0 24.5 3.3 358. 0
1951-52 0.0 0.0 5.0 30.0 45.5 22.5 38. 0 27.5 27.5 22. 3 15.5 3.3 235. 0
1952 0.0 0. 0 0. 0 7.8 67.5 82.5 _ _ — — — — —
*Trace • 12
will be mentioned later in this thesis. Tables 3 and
4 show weekly mean temperatures at the base of Sevuokuk
Mountain (8m or 25ft contour) and on the rim of that mountain (120m or 360ft contour) from 15 July to 13
September 1966 and 6 June to 7 September 1967. The occurrence of northeast gale force winds of 35 to 45 m.p.h. during the periods 28 August to 2 September,
7 to 10 September 1966, and 19 to 23 August, 28 August to 2 September 1967 adversely affected many chicks' departure for sea (see Chapter III) .
The marine environment inhabited by the auklets during the greater part of their life cycles has been described by Bedard (1967:29-33).
The avifauna of St. Lawrence Island has been
studied by Friedmann (1932), Fay and Cade (1959), and
supplemented by Sauer and Urban (1964), Thompson (1967)
and Sealy, Fay and Bedard (manuscript in preparation).
Fay and Cade (1959) divided the physical and vegetational
features of the Island into ten avian habitats; the
sea-cliff habitat, of which Sevuokuk Mountain is a
par_t, represents the type of nesting habitat most, densely
inhabited by birds on this Island. Bedard (personal
correspondence) estimated the total auklet population
on Sevuokuk Mountain to consist of about 183,000 Aethia
spp. and about 2,000 Cychlorrhynchus. Other avian species 13
Legend for Table 3
Air temperatures recorded at 8m contour and at 120m
contour on the northeast slope of Sevuokuk Mountain, 1966.
Temperatures measured in °C. TABLE 3
Mean Mean Period Maximum Minimum x Temperature
8 m Contour
July 15-21 12. 0 7.0 9.6 22-28 13.5 8. 2 10. 9 29-31 13. 3 8. 0 10. 6 August 1-7 12.4 9. 2 10.8 8-14 12.4 8.5 10.5 15-21 10.5 7.0 8.7 22-28 11.5 8.0 9.5 29-31 8.0 6.0 7.0 September 1-7 9. 2 6. 1 6. 2 8-13 9.3 7.5 8.3
120 m Contour
July 15-21 13. 8 7.8 10. 0 22-28 13.0 7.2 10.8 29-31 16.0 8. 6 12. 3 August 1-7 13.4 9. 2 11.0 8-14 12. 1 9.1 10.7 15-21 10. 2 6. 7 6.5 22-28 10.6 8.6 9.6 29-31 7.6 5.6 6. 7 September 1-7 9.4 5.7 7.5 8-13 8.5 6.0 7.2 14
Legend for Table 4
Air temperatures recorded at 8m contour and at 120m
contour on the northeast slope of Sevuokuk Mountain, 1967.
Temperatures measured in °C. TABLE 4
Mean Mean Period Maximum Min imum x Temperature
8 m Contour
June 6-7 7. 1 4. 2 5.6 8-14 7.8 4.5 6.1 15-21 8. 2 6. 7.9 22-28 9.3 6. 7.5 29-30 9.1 6. 7.4 July 1-7 12.8 8. 10.6 8-14 14. 8 9. 12.3 15-21 12.8 9. 11.6 22-28 29-31 10.3 8. 3 9.3 August 1-7 11. 2 10. 2 10.7 8-14 9. 6 8. 5 9.1 15-21 10. 5 6. 0 8.3 22-28 13. 4 8. 6 11.0 29-31 11. 2 7. 6 9.4 September 1-7 10. 1 7. 2 8.7
120 m Contour
June 6-7 7.0 4.0 5.5 8-14 14. 7 6. 3 10.5 15-21 15. 3 7.6 11.5 22-28 21.5 8. 7 15. 1 29-30 14.5 9. 0 11. 8 July 1-7 20. 1 10. 0 15.0 8-14 17. 2 11. 0 14. 1 15-21 16. 7 11.5 14. 1 22-28 18. 8 12. 0 15.4 29-31 14. 0 12. 3 13. 2 August 1-7 16.8 12. 6 14. 7 8-14 14. 7 11.5 13.1 15-21 13. 8 10. 7 12. 3 22-28 17.5 12. 7 15.5 29-31 14. 6 11. 3 12. 9 September 1-7 12.0 11. 2 11.6 which bred on the rock-pile cliffs of this mountain during the study, in approximate order of decreasing abundance, were:
Pigeon Guillemot (Cepphus columba) Horned Puffin (Fratercula corniculata) Snow Bunting (Plectrophanax nivalis) Tufted Puffin (Lunda cirrhata) White Wagtail (Motacilla alba) Raven (Corvus corax)
An account of the terrestial mammals of St.
Lawrence Island has been given by Rausch (195 7). Tundra shrews (Sorex tundrensis), arctic ground squirrels
(Citellus undulatus), red-backed voles (Clethrionomys rutilus) and tundra voles (Microtus oeconomus) live in juxtapostiion to the nesting auklets on Sevuokuk Mountain.
Arctic foxes (Alopex lagopus), fairly common residents in the Kongkok colony (Bedard, personal communication), were observed four times in the Sevuokuk colony during the study. Sledge dogs (Canis familiaris) frequently hunted in the colony and in 1967 three lived in the
Sevuokuk colony during the entire summer.
The vegetation of St. Lawrence Island, in general terms, is characteristic of the circumpolar tundra biome. Fay and Cade (1959) have summarized the sparse
literature on the flora of this Island and an ecological study of its vegetation is presently underway (S. Young, personal communication). The most predominant form of vegetation on the nesting slope was a low ground cover 16
composed of mosses and lichens; the most common genera of mosses were Ceratodon, Bryum, Camphylium, Drepanocladus and Pogonatum which grew on and among the rocks from about the 30m contour to the brow. Lichens were represented by Cladonia, Certraria and Alectoria. Shrubby species encountered were Rubus chamaemorus arid Salix spp. and the most common forbs were Sedum, Pedicularis and Saxifraga plus several genera of sedges.
C. Methods
In 1966 field-work commenced 13 May and ended on 14 September; in 1967 it began on 25 May and ended on 9 September. Nearly the entire period was spent in the Northwest Cape area of the Island, that is, on Sevuokuk Mountain and, in 1966, offshore on the Bering
Sea. Observations were made on 12 June 1967 in the
Kongkok colony on the southwest side of the Island
(figure 1) .
Permanent headquarters were established in
Gambell; temporary camp was set up on the northeast slope of Sevuokuk Mountain at Tategnak Point (figure 3) where observations and nesting studies were conducted.
The disappearance of snow and consequent exposure of nesting sites was quantitatively studied on the west slope of Sevuokuk Mountain by measuring the ratio of bare ground to snow-covered ground in each of five 17
plots on the west slope and three on the northeast slope,
14.2m to a side, at different elevations on the slope.
The plots were randomly selected in auklet nesting habitat. The dimension of 14.2m to a side was selected because it gave an area approximately 200 sq. m, a suitable area considering that the auklets' nesting habitat
in the talus slope is usually in the form of rock
"stripes." Birds "sitting" on a spcific area of the
snow were live-strapped using "noose carpets" (see Berger and Hammerstrom, 1962) and were banded and color-marked, using color combinations on each leg.
Samples of each auklet species were collected
at approximately weekly intervals during both seasons.
Samples of each auklet species were collected at sea with Jean Bedard usually between 1300 and 1700 hr (all
times in this thesis are Bering Sea Time) during the pre-egg, egg-laying and incubation stages. During the
chick-rearing and sea-going stages samples were taken on Sevuokuk Mountain. The stormy nature of the Bering
Sea climate largely dictated the intervals between successive
collecting trips at sea.. . The lack of water transportation
in-1967 necessitated sampling from the west slope of
Sevuokuk Mountain. A total of 45 psittacula (3 9 males,
6 females) was collected in 1966 and a total of 14
(7 males, 7 females) in 1967. A total of 212 cristatella (88 males, 104 females) was collected in 1966 and a total of 92 (53 males, 39 females) in 1967. A total of 223 pusilla (125 males, 98 females) was collected in 1966 and a total of 175 (101 males, 74 females) in
1967. Each bird was weighed to the nearest O.lg using a spring balance. Gonads were dissected; the length and greatest width of each testis or the diameter of the largest follicle were measured to the nearest 0.1mm with Kanon calipers, fixed in Bouin's picro-formol-acetic solution for 24 hours, and then preserved in 70% ethyl alcohol. The left testes were subsequently weighed to the nearest O.Olg on a Metier analytical balance.
Subcutaneous fat on each bird was quantitatively estimated using a scale of 0 to 4; 0 represents no subcutaneous fat and 4 refers to heavy fat depots. The presence and condition of brood patches were noted as well as body molt and molt of the remiges.
Egg-laying dates of each species were determined by dissection of adult females and by searching for
"potential" nest-sites among the rock interstices and then revisiting them until the single "egg appeared.
The latter method was successful provided that the nest-site was suitable, a condition rendered possible to assess only through experience and familiarity with an auklet's nest. A powerful flashlight proved essential in the search for nests. Scratch marks on the crevice
floor often indicated an auklet's egg would appear.
In 1967 the obtaining of egg-laying dates was simplified
by having a number of known nest-sites from 1966. Each
nest-site was numbered on a west-facing boulder (sheltered
from the northeast prevailing wind and rain) using
commercial red spray paint. Lengths and widths of
18 psittacula, 65 cristatella and 126 pusilla eggs were
measured to the nearest 0.1mm. Each egg was numbered
with the corresponding nest number. Nest entrance
perimeters were measured, by placing a length of string
around the entrance and subsequently determining the
distance on a measuring tape. The distance from the
perch to the nest entrance was measured with a meter
cha in.
Environmental temperatures were recorded to the
nearest 1.0°c using Bacharach continuous recording
thermometers. A thermometer was placed at the 8m or
25ft contour on the northeast slope of Sevuokuk Mountain
and a second thermometer was placed at the 120 m or
360ft contour near the rim of the mountain. Two
-thermometers with extension leads recorded the temperature
in a cristatella nest-site and a pusilla nest-site.
Wind velocity was measured using a "Florite" wind gauge.
Body temperatures were measured by means of a portable, 20
battery-powered, multi-channel thermister thermometer manufactured by the Yellow Springs Instrument Company,
Yellow Springs, Ohio. All thermisters were calibrated with a Bureau of Standards thermometer; temperatures were measured by gently inserting a vinyl-sheathed thermister probe down the esophagus to the stomach, and read after
120 seconds (testing showed that by this time "normal" temperatures were registered). Chicks were removed from their nest-site and measurements were taken within 30 seconds.
As Farner and Serventy (1959) pointed out, this type of temperature measurement admittedly involves bias (Udvardy,
1953) which could be eliminated using permanently installed thermocouples (Bartholomew and Dawson, 1954); however, such a procedure was not feasible here due to the high loss of chicks. Burrow temperatures were measured simultaneously with the chick body temperatures by placing a vinyl-sheathed thermister probe into the burrow after the chick was removed. Egg temperatures were obtained by slipping a vinyl-sheathed probe 3mm in diameter through.a small hole drilled through the shell.
Pipped egg temperatures were obtained by gently inserting this probe through the pip hole and placing the probe against the embryo.
Standard aluminum bands issued by the United
States Fish and Wildlife Service were applied to each nestling studied, no. 4 for psittacula and cristatella and no. 2 for pusilla, at four to five days of age for the former two species and at about three days of age for the latter. Each chick was weighed each day between
1000 and 1400 hr using a spring balance, accurate to the nearest O.lg. The culmen, tarsus, outer primary and number 1 rectrix were measured on each chick to the nearest
0.1mm using Kanon calipers for the culmen and tarsi and a plastic ruler for primaries and rectrices.
The methods involved in the collection and analyses of the food data are treated by Bedard (1967).
D. Distribution of North Bering Sea Auklets
Breeding colonies of the Parakeet, Crested and
Least auklets in Alaska and eastern U.S.S.R. have been described by Gabrielson and Lincoln (1959) and Kozlova
(1957), respectively. These distributions have been recently mapped and analysed by Udvardy (1963).
Cychlorrhynchus and A. cr istatella have identical general ranges (Udvardy, 1963); however, as seen in Gabrielson and Lincoln (1959) and Bedard (1967), the former species has the more ubiquitous distribution in the Bering Sea.
Cychlorrhynchus nests on the coast of the Chukotsk
Peninsula, on the Commander Islands, in the Sea of
Okhotsk at Ayan, and in Alaska on the islands in the
Bering Sea, and on the Aleutian Islands (Kozlova, .195 7).
A. cristatella breeds on the eastern end of the Chukotsk Peninsula, the Diomede Islands, Sakhalin, and the central
Kurile Islands, in eastern Siberia, and from the Pribilof and Aleutian Islands east to the Shumagin Islands,
Alaska (A.O.U. Chick-list, 1957:254). A. pusilla, exclusively endemic to the Bering Sea, shows a different breeding range than cristatella in that it does not breed on the Kurile Islands and south of the Aleutian
Islands. The fourth closely related auklet, A. pygmaea, would, according to Udvardy (p. 91), "fit into the range pattern of the other two Aethia auklets if we could credit Captain Cook's account as a worthy documentation of its former nesting on the Islands of the Bering Sea. "
This species is presently restricted to the east side of the Pacific Ocean.
E. Migration, Dispersal and Winter Distribution of
North Ber ing Sea Auklets
Migration, dispersal and winter distribution of Parakeet, Crested and Least auklets are poorly known due to their relative inaccessibility on their nesting grounds, the consequent lack of banded birds and the scarcity of observations on their wintering grounds.
The postbreeding dispersal of chicks and adults from the Sevuokuk colony is a matter for speculation. Whether they stay in the vicinity of St. Lawrence Island for any length of time is not known; small flocks of cristatel and pusilla have been seen, however, northwest of Gambell
in late fall by walrus hunters (L. Kulukhon, personal
communication) but it is impossible to be sure that
these are part of the St. Lawrence Island breeding
population. Tuck (1961) stated that for the next several
weeks after young and adult murres (Uria spp.) have gone
to sea they swim northwards against the currents.
Other workers, namely, Johnson (1940), Stechow (1938) ,
Landsborough-Thomson (1953) and Uspenski (1958) have
also demonstrated the rather wide dispersal of Uria,
especially young ones after the breeding season. Austin
(1932) found that young Black Guillemots (Cepphus grylle)
also dispersed widely after the breeding season and in
his study of Common Puffins (Fratercula arctica), Lockley
(1953:201) stated that "It is significant that juvenile
sea-birds, as we are discovering by ringing, may perform
the longest migrations of their lives in their first
winter. " The widespread movements of F. arctica have
also been discussed by Landsborough-Thomson (1953) while
the migrations of Razor-billed Auks (Alca torda) have
been studied by Lonnberg (1938), Solomonsen (1944) and
Thomson (1953) in the European Atlantic and by Bedard
- (1964) on the American side of the Atlantic Ocean.
The decreasing temperature in late fall in the
north Bering Sea area and the resulting advancing edge 24
of sea ice which forms is no doubt largely responsible for the southward movements of psittacula, cristatella and pusilla out of the St. Lawrence Island waters in winter. The. s.ea ice forms here about the end of
November (Fay and Cade, 1959); the southern limit of floating ice in the Bering Sea is usually in the vicinity of the Pribilof Islands (U.S. Weather Bureau, 1925).
The importance of ice as a causative factor in the movements of alcids in winter has been indicated for the following species: Alca torda (Bent, 1919), Uria spp. (Bailey, 1948; Bent, 1919; Salomonsen, 1944; Tuck,
1961; Uspenski, 1958; and others), Plautus alle (Bent,
1919; Uspenski, 1958), Cepphus grylle (Bailey, 1948;
Bent, 1919), C. columba (Bent, 1919), Cychlorrhynchus psittacula (Bent, 1919), Aethia cristatella (Bent, 1919;
Kozlova, 1957), Fratercula arctica (Bent, 1919) and
F. corniculata (Bent, 1919).
Cychlorrhynchus has been recorded throughout the winter around the Pribilof Islands (Preble and McAtee,
1923), at Dutch Harbor (Cahn, 1947) and near the Aleutian
Islands (Murie, 1959) contrary to Bent (1919) and Gabrielson and Lincoln (195 9). Along the American coast it has been reported off the states of Washington (Balmer, 1935) and California (Beck, 1910). On the Asiatic side of the
Pacific Ocean it has been reported in the Kurile Islands, Sakhalin and Hokkaido (Gizenko", 1955) and South Sakhalin
(Shuntov, 1965). A. cristatella and numbers of A. pusilla winter near the Pribilof Islands (Preble and McAtee,
1923) and are both abundant along the Aleutian chain
(Murie, 1959). Neither cristatella nor pusilla travels along the American coast, however, there is a report of an accidental occurrence of cristatella off Washington state (Nickelsen, 1942). Both the latter species are common in winter in the Kuriles (Gizenko, 1955), in the Sea of Japan (Shuntov, 1965) and along the shores of Sakhalin and Hokkaido (Gizenko, 1955). THE BREEDING SEASON
CHAPTER I. The Pre-Egg Stage
Bedard's (1964) concise definition of the pre-
egg stage in a sea-bird colony will be used here, viz.,
the period which extends from the time most of the birds have arrived back at the colony until the first egg
is laid.
A. Arrival of Auklets at the Breeding Colony
The arrival of Parakeet, Crested and Least auklet
in the St. Lawrence Island waters and on the nesting
slope on Sevuokuk Mountain in the springs of 1964, 1965
and 1966 have been discussed and tabulated by Bedard
(1967, table 1), To his table 1 I have added dates
of first occurrence of each species in the offshore
leads and on the nesting slopes in 1967 (see table 5,
dates obtained from C. Ray, personal communication).
Each species arrived earlier in 1967 than the previous
three years.' This is~in accordance with the earlier
spring phenology on St. Lawrence Island in 1967.
Temperature records for early May in each of the four
years are lacking. Legend for Table 5
Arrival dates in May of auklets on St. Lawrence
Island during 1964 to 1967 seasons. Data for 1964 and
1965 are from Bedard (1967), for 1966 from Bedard and this study, for 1967 from this study. TABLE 5
C. psittacula A. cristatella A. pusilla . 1964 1965 1966 1967 1964 1965 1966 1967 1964 1965 1966 1967
First seen in offshore leads 13 9 4 18 13 15 10
First seen from shore 15 18 20 15 18 20 15 18 21
First seen on slopes 19 21 24 20 22 24 18 20 22 24 20 28
B. Effect of Snow Cover on the Onset of Nesting
The extent and persistence of snow cover encountered by arriving and settling auklets on the nesting slope was considerately different in 1966 and 1967. In 1966, a late season, snow cover was about 95 percent on the date settling first occurred (figure 4); in 1967, an early season, it was about 60 percent. The mean temperature at Gambell, two miles west of the Sevuokuk colony, from
21 May to 15 June 1966 was -1.0°C and from 26 May to
15 June 1967 was 7.0°C. As will be seen later, however, despite this temperature difference snow cover at the time of egg-laying was the same in both years; snow was present only along the brow of the mountain (figure 6).
Snow melts at different rates on different parts of the slope depending upon exposure and elevation. This results in portions of the slope being covered with snow, particularly along the brow (figure 5), while the other portions of the slope are free of snow. Thus, at this stage of the breeding cycle, the auklet population is divided into those that are courting on the snow and those that are courting on the rocks and actually searching for nest-sites under them (figure 7). The pattern of egg-laying in different portions of the slope in relation to exposure to sunlight was not examined due to the inaccessibility of most nest-sites which rendered Legend for Figure 4
Pattern of snow-melt on Sevuokuk Mountain in 1966 and 1967. Five plots were selected at random at different elevations in auklet nesting habitat on the west slope and three on the northeast slope. Each point represents mean value of estimated snow-free nesting habitat from each plot. Value of 0 indicates snow and ice-free nesting crevices. Percent snow-cover on plots 30
Legend for Figure 5
Snow-cover on west slope of Sevuokuk Mountain, St.
Lawrence Island, 2 June 1967. Note presence of snow-free
and snow-covered slope.
Legend for Figure 6
Sevuokuk Mountain, northeast slope, 23 June 1967.
Note presence of snow only along the rim. quantitative data impossible to obtain. I will treat
A. pusilla in this analysis but A. cristatella is equally involved but C. psittacula, predominantly a cliff-nester is effected by snow cover to a lesser extent.
In 1966 and 1967 snow persisted along the brow of the northeast slope of Sevuokuk Mountain until about
12 July despite the difference in snow melt in these two years. Comparing egg-laying of A. pusilla (Chapter II in 1966 and 1967, an interesting situation is evident.
As may be seen in figure 8, this snow on the brow covers much auklet nesting habitat. Egg-laying in 1966 spanned the period 24 June to 7 July in those nests studied; those auklets "sitting" on the snow on the brow had access to snow-free nesting habitat a few days later and were thus able to lay their eggs almost immediately after those on the snow-free lower portions of the slope.
In 1967, a different pattern of egg-laying existed; the slope and crevices were completely free of snow by 8 June (figure 4) except for that which persisted on the brow until about 12 July. Higher temperatures during the pre-egg stage in 1967 resulted in nesting crevices being cleared of snow earlier which permitted those auklets on the snow-free areas to commence egg- laying while the persisting brow-snow prevented those birds on it from reaching the nesting crevices. Egg-layin Legend for Figure 7
Crested and Least auklets settled on rocks and snow on the northeast slope of Sevuokuk Mountain, 25 June 1967.
Note fidelity of birds to snow-covered rocks despite proximal snow-free rocks.
Legend for Figure 8
Auklets (Aethia spp.) "sitting" on the snow at the brow of the northeast slope of Sevuokuk Mountain, 25
June 1967. Note the nonrandom distribution of birds on the slope. in 1967 spanned the period 13 June to 25 June in those nests studied on the lower snow-free part of the slope; however, the persisting snow on the brow resulted in nesting failure of those birds faithful to that part of the slope. On 22 June eggs began to be laid on the brow snow and were subsequently destroyed because they rolled down the snow and broke or were taken by gulls.
Observations of auklets settled on the snow- covered slope revealed that the scattering of the birds was not random (figure 8). It appeared that these birds, unclassified as to experienced or inexperienced breeders, were familiar with the nesting slope and possessed a high degree of location for apparently nesting would occur among the boulders below them when the snow melted.
This apparent sense of location was exhibited by Plautus alle, Cepphus columba, C. psittacula, Aethia spp., and
Fratercula arctica on St. Lawrence Island and was borne out in A. cristatella and A. pusilla using banded and color-marked adults captured on the snow. Table 6 presents banding data and subsequent observations of these birds; four retraps of incubating adults (two
each of cristatella and pus ilia) provide positive evidence
that they are capable of finding their nest-sites even when snow covers them. Legend for Table 6
Banding and subsequent observations of A. cristatella and A. pusilla in 1966 and 1967. Each adult was live- trapped on top of the snow at about the 20m contour on the northeast slope of Sevuokuk Mountain. The subsequent observations were made in or near the nesting habitat which was covered by snow when they were banded. TABLE 6
Activity When Species Date Banded Date Observed Observed
A. pusilla 15 July 1966 5 July 1966 Incubating egg* A. pusilla 15 June 1966 9 July 1966 Incubating egg* A. pusilla 19 June 1966 3 August 1966 Carrying food to chick A. cristatella 15 June 1966 4 August 1966 Carrying food to chick A. pusilla 19 June 1966 10 August 1966 Carrying food to chick A. cristatella 12 July 1967 15 July 1967 Incubating egg* A. cristatella 12 June 1967 3 August 1967 Incubating egg* A. cristatella 12 June 1967 16 August 1967 Flying A. cristatella 12 June 1967 21 August 1967 Carrying food to chick
Observations supporting the apparent sense of location possessed by these species. C. Colony Structure
Drent (1961) pointed out that the apparent
"disorderly mobs" in a sea-bird colony actually represent
a well-organized system. Various descriptions of Crested
and Least auklet colonies illustrate the apparent chaotic
situation which exists on the nesting slopes. On the
Pribilof Islands, Gabrielson and Lincoln (1959:506) described the auklets which "had been swirling like
swarms of insects, the air over the village was filled with hurrying flocks, " and later (p. 508) "As evening
advanced, the flocks of Least Auklets increased in size
until the clouds of individuals were like the great black-bird swarms of the Gulf Coast. These flocks circled
and swirled as ribbons and drifts of black or occasionally white, smoke on the skyline or shadows over the water,
twisting and turning in fantastic figures." Nelson
(1887) portrayed Big Diomede Island as only to be likened
to a vast beehive, with the swarm of bees (auklets)
hovering above it.
The careful observer soon realizes that "order
out of chaos" does prevail in an auklet colony. However,
only a sketch of the social structure in Parakeet, Crested,
and Least auklets can be offered since marked non-breeders
and adults were unavailable or too few to allow meaningful
observations to be made. It appears from the limited data available that year-to-year stability within the colony exists; the mated pairs remain intact in successive years and use the same nest-sites as long; as they remain undisturbed. Yearling birds are present in the colony but it is not known if they return to their birthplace.
Two-year-old birds are also present, however, it appears that they do not breed; whether auklets first breed in their third year is uncertain (Bedard, 1967) .
a. Pair-bond in auklets
The small sample of banded and recaptured adults
incubating eggs provides evidence that mafce-retention occurs but does not allow one to say that .it is the general rule in the auklets. Three pairs iof A. pus ilia
(nests #37, 82, and 151) and one pair of M.. cristatella
(nest #19) were banded in 1966. Two pairs of A. pusilla
(nests #3 7 and 151) and the pair of A. cristatella were recaptured in 1967 in the same nest—sites. One of the third pair of A. pusilla (nest #82)) was caught
in 1967. The immense number of breeding auklets in this colony precluded the discovery (without Im site changes or "divorce" cases (see Dremtt, 1965). _C. psittacula probably retains the same mates more than one season, however, since none was bandexd in 1966 it is not possible to be sure. Capture of adults on accessible nests was the method of banding, and is facilitated by the nature of some of the nest-sites which generally confine the adult and enable one to catch it by hand. Recapture was by the same method. In the other auks, mate retention has been recorded in Uria aalge and U. lomvia (Tuck, 1961), Cepphus columba (Drent, 1965) and Cerorhinca monocerata (Richardson, 1961). The situation mentioned in C_. columba, where the birds generally pair for several years but divorce may occur (Drent, 1965), has also been reported in U. lomvia (Uspenski, 1958) . b. Nest-site tenacity From the preceding section it was found that Crested and Least auklets use the same nest-sites of the previous year. Three pairs of A. pusilla (nests #37, 82 and 151) and one adult from each of two pairs (nests #32 and 57) were banded in 1966; one pair of A. cr istatella (nest #19) was also banded that year. Recaptures in 1967 showed the following results: h.- pusilla: Nest #37 - pair present Nest #82 - one adult present Nest #151- pair present Nest #32 - present Nest #57 - nest crevice destroyed A. cristatella: Nest #19 - pair present Observations of auklets on the snow during the pre-egg stage lead me to conclude that nest-site tenacity is highly developed in Parakeet, Crested and Least auklets. As discussed earlier in this chapter, auklets arrive on the slopes and distribute themselves on top of the snow. This distribution and subsequent behavior (pairing had occurred in most cases by this time) indicated that they possessed a high degree of location. The adaptive value of this nest-site tenacity becomes apparent when the pattern of snow melt from the slope is studied. Snow disappears from the slope at different rates in different portions of the slope which results in areas of snow-free and snow-covered nesting habitat adjacent to each other (figure 7). Egg-laying in relation to snow melt was studied in several nest-sites in 1967 and was found to occur in many cases within a few days after the crevice was free of snow. The following observations illustrate this point more clearly: _C. psittacula nest #14, elevation approximately 120m, northeast slope; pair displaying on snow directly over nest crevice at 0300 hr on 3 July. At 0100 hr on 6 July the crevice was devoid of snow and occupied by the pair. On 7 July at 1830 hr an egg was present. A. cristatella nest #32, elevation approximately 30m, northeast slope; covered with snow on 22 June. Egg present at 0230 hr on 25 June. A. pusilla nest #29, elevation approximately 75m, northeast slope; covered with snow on 22 June. At 0100 hr on 24 June an egg was present in the nest-site. These observations show that despite the fact that snow melt may occur at different times each year (three weeks earlier in 1967 compared to 1966), there is reduced competition for nest-sites which could be time consuming and critical if all birds competed for nest-sites at the first available snow-free areas as in the case of Brant (Branta bernicla) (Barry, 1962) . As pointed out by Drent (1965), all species of auk studied show a pronounced nest-site tenacity: Alca torda (Landsborough-Thomson, 1953; Kartaschew, 1960), Uria aalge (Storer, 1952; Landsborough-Thomson, 1953; Tschanz, 1959; Kartaschew, 1960; Tuck, 1961), U. lomvia (Uspenski, 1958; Kartaschew, 1960), Cepphus grylle (Storer, 1952), C. columba (Drent, 1965), Fratercula arctica (Landsborough-Thomson, 1953) and Cerorhinca monocerata (Richardson, 1961). c. Territoriality As suggested by Bedard (1967), these auklets are presumed to be territorial and to defend a single interstice or nest-site (Type "C" territory of Hinde, 1956). The effectiveness of this nest-site defence is indicated by the fact that, despite the immense number of nesting auklets in this colony, they utilize the same nest year after year. Evidence for this territoriality was, however, difficult to obtain for it is impossible to observe the birds' behavior on their nests. This difficulty also precluded determining whether, during 40 the chick-rearing stage, this intolerance declined as is the case in F_. arctica (Lockley, 1953) . Other alcids exhibit a similar type of territoriality (Drent, 1965 in C_. columba; Lockley, 1953 in F. arctica; Thoresen, 1964 in Ptychoramphus aleutica), and defend the approach to their respective nest-sites (Bedard, 1964 in A. torda). d. Non-breeders Observations on non-breeding auklets are in conformance with those of Bedard (1967) and do not add significantly to his description (p. 14-16) . D. Copulation Copulation or attempted copulation in auklets was observed only once at sea (Bedard, personal correspondence) and never on the surface of the nesting slopes (Bedard, 1967; this study). Bedard felt that it would be surprising if it could occur in such places owing to the peculiar intruding system involving non-breeders and to the fact that immature birds would quickly disrupt and prevent efficient copulation in such situations. Except in one .instance, observations in this study support Bedard who found copulation to probably occur in the nest-site. As discussed earlier, many auklets laid eggs on top of the snow in 1967; internal examination of several of these Aethia eggs revealed the presence of a blastodisc in three cristatella and two pusilla eggs which indicates that copulation and fertilization had taken place. Several other Aethia eggs laid on the snow were infertile This copulation possibly took place at sea for about 55 hr of observations of auklets on the snow showed no copulatory acts carried out there. Copulation, as well as other behavior on the nest was usually impossible to observe because it occurred in the dark recesses of the nest-site and in the three instances where it was briefly observed this was accomplished by accident while searching for active nests with a flashlight. In each case the presumed male was mounted on the back of the female in a manner similar to that described for Cepphus (Drent, 1965). In each of these observations, two of cristatella and one of pusilla, the birds "froze" immediately upon being struck by the light and ceased all forms of sexual behavior. Observations presented in the section on pair-bond show the apparent short time involved between snow melt and egg-laying in some pairs; copulation probably occurs within this period. Drent (1965) observed copulation in C. columba up to 28 days prior to laying the first egg; the rate of copulation jumped to a maximum in approximately the last 12 days prior to egg-laying. The time elapsing between copulation and the first fertil egg obtained in chickens has been reported by many investigators (see review by Parker, 1949) . The time averages about 72 hours, but may be as low as 19.5 hours, according to one report. The latter figure, if correct, means that the egg may be fertilized while it is in the magnum or isthmus (Sturkie, 1965). Provided that auklets possess similar capabilities regarding fertilization and laying, it would be possible for eggs to be fertilized and laid in nest-sites that have been free of snow for only three or four days. The lack of observations of the sequence of events preceding, during and following copulation in auklets precludes a general comparison with other auks; however, a few points are of interest. Copulation in Alca and Cepphus, which takes place on land, has been described by Bedard (1964) and Drent (1965), respectively. The former species copulates in their nest-sites while the latter species utilizes their beach perch-sites. In Uria spp. copulation also occurs on the nest-site (Storer, 1952; Tuck, 1961) and only in rare cases does it occur on water (Tuck, 1961) ; the latter site provides the site for copulation in _F. arctica (Fisher and Lockley, 1954; Myrberget, 1962). Nothing is known about the vocalizations, if any occur, uttered by auklets during copulation as is common in some alcids, e.g. Cepphus (Drent, 1965), Uria spp. (Tuck, 1961) and Alca (Bedard, 1964). CHAPTER II. The Egg Stage A. The Nests of Parakeet, Crested and Least Auklets a. Description of the nesting environment The plankton-feeding alcids are intimately associated with talus slopes during the breeding season on St. Lawrence Island. Here, rock, in varying degrees of disintegration and position on the slope, provides through physical contact with each other the crevices and interstices utilized by auklets as nesting sites. Talus slopes or scree are produced mainly by weathering of cliffs which is aided by mass-wasting, the bulk transfer of masses of rock debris down slopes under the direct influence of gravity. Talus may be formed by frost action, a form of weathering, which acts on a cliff-face resulting in rock breaking at the level of the joints. Upon breaking away from the parent rock the loose particle tumbles down the slope due to the gravitational pull and comes to rest at the bottom of the slope. Continued accumulation of rock debris at the bottom of the slope, provided wave action or ice scouring do not remove the particles, results in the talus creeping or retreating upwards. Eventually, if the rock waste accumulates more rapidly than it can be destroyed or removed, even the upper cliffs become buried, and the growth of the talus ceases. The slope angle of the talus varies with the size and shape of the rock fragments (Leet and Judson, 1965); the angle of the talus slope on Sevuokuk Mountain is about 30 degrees, depending upon where the measurement was made. For a detailed description of the nesting slopes on" Sevuokuk Mountain the reader is referred to Bedard (1967). The micro-environment utilized by Aethia spp. for nesting purposes is the mantle of rock debris that covers entire slopes or parts of slopes. The mantle, according to Bedard (1967), is the covering of cobbles and boulders on talus slopes. It is limited in thickness by the inter-face air-slope on one hand, and by the "floor" on the other and does not generally exceed five meters in thickness. The floor or lower limit of the mantle is made of the unfractured parent rock or, more often, is the result of the accumulation and settling of fine particles with the production of a relatively flat or uniform surface (Bedard, 1967). It is necessary at this stage to point out that it was impossible to have access to all nests of Aethia spp. in the rock mantle or even a given sector of the mantle. Without manipulating and consequently destroying nesting habitat, one was unable to reach and observe most of the nests. Consequently, those nests studied 46 were accessible because of their marginal location or their nearness to the surface of the mantle. It was found that nests would be deserted if adjacent rocks were removed to provide access for study purposes even though they were replaced as closely to their original position as possible. This precluded obtaining much important information such as: differential egg-laying on different parts of the slope, the effects of social stimulation on egg-laying, production statistics, impact of predation, pre-sea-going mortality, etc. On Walrus Island, Bent (1919) found Parakeet, Crested and Least auklets nesting under loose piles of water-worn boulders which were piled up in a great ridge . in the beachlike centre of the Island, connecting the higher extremities. On the Pribilofs, Parakeet Auklets usually lay their eggs beneath large boulders or in practically inaccessible cavities in the cliffs; in some cases the eggs are deposited in burrows apparently excavated in the loose soil topping the volcanic cliffs (Preble and McAtee, 1923). Murie (1959) described Parakeet's nesting habitat in the Aleutians as being among large boulders on the beach, in crevices in rocky cliffs and on slopes where rocks are partly covered by vegetation. Cade (1952) found a single pair inhabiting a burrow under loose rocks which had fallen down from the cliffs and piled up in a mass at the water's edge on Sledge Island. On the Commander Islands, Stejneger (1885) found Parakeet Auklets breeding in steep, cracked and inaccessible rocks. Turning to the Crested Auklet, according to Preble and McAtee (1923), on the Pribilofs this species usually nests about the high cliffs. The single white egg is deposited in deep and usually inaccessible recesses; occasionally the birds lay their eggs in the depths of boulder beaches. On the Aleutian Islands, they nest deep in crevices among boulders on the beach, in cavities in cliffs or among jumbled lava rock on high slopes (Murie, 195 9) . Kozlova (195 7) stated that Cresteds nest among cliffs and stone heaps on the sea- coast, frequently in company of Parakeet Auklets; the single white egg is laid between stones, without lining, or inside a deep crevice of a cliff. Nesting of Least Auklets on the Aleutians and west coast of U.S.S.R. has been described by Murie (1959) and Kozlova (1957) , respectively as being similar to Crested Auklets. During this study.about 800 nests of Aethia spp. and about 60 nests of Cychlorrhynchus were examined. Despite the fact that the percentage of nests in each nest-type category cannot be given due to their general inaccessibility it is felt that all existing nest-types for each species in the Sevuokuk colony have been observed. 48 Cychlorrhynchus occupies the same general nesting habitat on St. Lawrence Island as described by the above writers; however, Aethia spp. will be shown to have a more complex nesting distribution than one is led to believe by their descriptions. Neither Crested nor Least auklets accumulate nesting material but instead lay their eggs under the boulders on the floor of the mantle or in a crevice formed at the angle created by contact of two or more boulders. Cychlorrhynchus also does not accumulate nesting material. Most eggs of each species were laid on dirt but in some nests small pebbles accumulated on the floors upon which the eggs were deposited. Figures 9, 10 and 11 illustrate the types of Parakeet, Crested and Least auklet nests, respectively, encountered in the Sevuokuk colony. In every nest examined the egg was in near total darkness and always under a rock or peat. b. Segregation on the nesting slope During a study of ecological segregation among Cychlorrhyrichus and Aethia spp., Bedard (1967) demonstrated that segregation on the nesting slope is complete between the two genera, Cychlorrhynchus being primarily a scarp- face nester while Aethia spp. occupy the talus slopes. In the latter habitat, Bedard (1967) looked at one aspect of the relations between auklets and the nesting environment. Using concepts of slope morphology and slope 49 Legend for Figure 9 Cross-sections of main nest types of Parakeet Auklets on Sevuokuk Mountain, St. Lawrence Island. Stippling indicates soil; clear portions indicate rock. A B A crack in a scarp B in mantle covered by vegetation C under large boulder D crevice among splintered parent rock 50 Legend for Figure 10 Cross-sections of main nest types of Crested Auklets on Sevuokuk Mountain, St. Lawrence Island. Stippling indicates soil; clear portions incidate rock. A under stones B in mantle covered by vegetation C in interstices (top view) Legend for Figure 11 Cross-sections of main nest types of Least Auklets on Sevuokuk Mountain, St. Lawrence Island. Stippling indicates soil; clear portions indicate rock. A B processes, he showed the patterns of segregation between the two species of Aethia and gave some evidence to the effect that broad-scale geomorphic processes can affect the overall abundance and relative proportions of these two species in various parts of their breeding ranges. He demonstrated that the marked difference in body size between A. cristatella and A. pus ilia is responsible for segregation, acting through one principal factor, the average rock diameter on the slopes. His thesis is that the density of cristatella increases linearly with increasing boulder size; the density of pus ilia decreases both with decreasing boulder size and with decreasing abundance of its larger congener. To illustrate this segregation I have utilized figure 38 of Bedard (my figure 12) and his discussion of it. The left part of the curve for pusilla falls very abruptly after reaching a maximum rock-size diameter of about 3.0dcm. This part of the curve has not been documented but rather has been drawn from qualitative observations. A decrease in the average size of the particles is general accompanied by clogging of the interstices, soil formation and vegetation development; such conditions develop rather rapidly between mean values of 3.0 and 2.0dcm. At the other extreme of the graph, in the domain of cristatella, there is an obvious limit to talus slope formation with particles exceeding an average diameter bf lO.Odcm; 53 Legend for Figure 12 Generalized model showing the segregation between Aethia cristatella and A. pus ilia on the nesting slopes according to average rock diameter. From Bedard (1967:123). 54 this may occur in some areas but in the Sevuokuk colony such large blocks accumulated at the base of the talus slope to form the "rubble". If these blocks are large enough, they will resist removal by wave and ice action while the finer particles will be removed between them. At any rate, this habitat is usually occupied by other alcids such as Cepphus and often, Fratercula. Furthermore, the increase in particle size above a certain limit brings about a direct decrease in the possible number of interstices and this probably accounts for much of the drop that occurs in the density of cristatella between values of average rock diameter of 7.0 to lO.Odcm As pointed out by Bedard and observed in this study, it becomes possible even after short field experience in this alcid colony to recognize fairly accurately the regions on the slope where one is likely to encounter one or the other genus of Alcidae. Six species of alcids breed in the Sevuokuk colony, each species at one time or another is associated with one another to varying degrees. Cepphus nests predominantly among the "rubble" at the base of the slope but may also be found elsewhere on the slopes where very large boulders exist and in lesser numbers on scarp-faces. Lunda and Fratercula, primarily burrow-nesters throughout most of their range, are also encountered nesting among the "rubble" and cliffs. It is difficult to describe in quantitative terms just what a Cepphus nest is that makes it different from, for example, the nest of Lunda. This difficulty was also encountered during the present study for, despite the general segregation of Cychlorrhynchus and Aethia spp. on the nesting slopes, many instances of overlap in nesting among these species were found. On numerous occasions nests of cr istatella and pusilla, cristatella and psittacula, and sometimes all three species were found within about a meter of each other and in some instances within a few centimeters of each other. It was apparent upon examination of the perimeters of the nest-site entrances of each species (table 7) that the great differences in body size between pusilla and cristatella on one hand, and between pusilla and psittacula on the other accounted for nest-site segregation where pusilla overlapped with the other two species. A. pus ilia nests in crevices too small for either psittacula or cristatella to "squeeze" into, whereas the difference between a psittacula and cristatella nest was not as obvious. I feel that the overlap in nesting among these species, .when it exists, occurs in the following manner: pusilla overlaps cristatella and to a lesser degree, psittacula, and cristatella overlaps psittacula. A. pusilla is often encountered nesting in "typical" cristatella habitat, but it utilizes the smaller and obviously less numerous crevices in the Legend for Table 7 Mean measurements of nest entrance perimeters, perch to nest entrance distances and time elapsed from landing on perches to entering mantle or nest-sites in Parakeet, Crested and Least auklets on St. Lawrence Island, 1967. The first number in parentheses is the sample size followed by the range of values. TABLE 7 Species Perimeter of Distance from Time Elapsed from Nest Entrance Perch to Nest Landing on Perch (cm) Entrance to Entering Mantle (m) or Nest-sites * (minutes) c. psittacula 38. 4 (16:25.4-48.6) 2.4 (22:0.6-4. 7) 20(11:12-35) A. cristatella 40. 3 (5:31. 6-48.4) 0.9 (5:0.3-2.1) 3(17:1-6) A. pusilla 23. 9 (7:16.1-28.2) 0.5(8:0.2-1.1) 2(21:0.5-5) . * Measurements taken during chick-rearing period, adults carrying food to their chicks. 57 large particles. These smaller crevices are unavailable to the larger cristatella and thus, nesting segregation is still complete. The reverse situation does not occur, in other words, cristatella is absent in areas where particles down to 2.0dcm exist and hence pusilla abounds exclusively. In the Sevuokuk colony, Cychlorrhynchus appeared to nest equally on the talus slope where weakly weathered outcrops appear at the surface in the form of ridges (primarily along the brow of the mountain) and where partially fractured parent rock comes to the surface. Cych1orrhynchus was never found nesting amid rounded boulders, as appears to be the case on the Pribilof Islands (Bent, 1919) , which support the bulk of the Aethia spp. breeding population. However, pusilla and cr istatella, particularly the latter, were often encountered nesting in areas occupied by Cych1orrhyn chu s. What differentiates between a cristatella and a psittacula nest-site in areas of overlap posed a problem which I have by no means solved. However, some observations are interesting. Bedard (1967) suggested that hypothetical factors of the micro-habitat may influence nest-site selection, the habits of the two Aethia may be effected by the condition of the substrate or the differential use they make of the mantle. These possibilities were considered in this study and it will be shown that the latter may be of particular importance. 58 From table 7 we see, as is to be expected by their equal body size, that nest entrance perimeters of psittacula and cristatella are similar. Recordings of nest-site temperatures of these species (tables 14 and 24 and figure 16) revealed no gross differences that might influence nest-site selection. A more subtle factor or factors appeared to operate. Differences in behavior of Cychlorrhynchus and Aethia adults during the chick-rearing period may be important. On their perches, Cychlorrhynchus is lethargic and inactive compared to Aethia, even though the former is equally agile on rocks and can scale vertical rock faces. Upon alighting on its perch which is usually some distance from its nest-site (table 7), Cychlorrhynchus is very slow in approaching its nest. Much time is spent sitting on the perch and peering around before attempting to walk over the rocks to the nest. The walk from the perch to the nest is usually interrupted by several stops. Finally, the mantle in which the nest is located is reached, a final stop occurs and then the adult slips into the nest. The time involved from landing on the perch to entering the nest may be up to 35 minutes but averages 20 minutes (table 7). Crested and Least auklets, however, are much more active on the rocks, their perches are less distant from their nests and a short time is involved between landing on their perches and entering their nests (table 7). Weather probably affects this time period but most of the observations were made simultaneously and are thus considered to be comparable. Every Crested and Least auklet nest examined was entered from below or at an angle similar to that of the nest floor, usually a distance being traversed in the mantle before the nest-site was reached. Only in cristatella nest-type B and pusilla nest type C were the nests entered directly from the outer surface of the mantle; the nests were still entered from the side or from below. Out of 47 nests of Cychlorrhynchus studied on the talus slopes, 39 or 73 percent were entered directly from above, a situation never encountered with Aethia nests. The remaining 17 percent were entered from the side directly from the outer surface of the mantle. Thus, innate nest-site preferences may operate within these species at the individual level of segregation. B. Egg-laying in Auklets , a. The seasonal pattern of egg-laying Egg-laying dates-are available - for C. psittacula, A. cristatella and A. pusilla in 1966 and 1967. The date when each clutch was laid is plotted in figures 13, 14 and 15. Dates of egg-laying were obtained by direct observations (the solid squares) and are accurate to within about six hours; those dates obtained by dissection of 60 Legend for Figure 13 Egg-laying in Parakeet Auklets on Sevuokuk Mountain, St. Lawrence Island. Solid squares indicate positive egg-laying dates obtained by direct observation; open squares indicate dates obtained from dissection of fully- shelled eggs in the oviduct. 0 certain D fully-shelled egg in oviduct 61 Legend for Figure 14 Egg-laying in Crested Auklets on Sevuokuk Mountain, St. Lawrence Island. Solid squares indicate positive egg-laying dates obtained by direct observation; open squares indicate dates obtained from dissection of fully- shelled eggs in the oviduct. 62 Legend for Figure 15 Egg-laying in Least Auklets on Sevuokuk Mountain, St. Lawrence Island. Solid squares indicate positive egg-laying dates obtained by direct observation; open squares indicate dates obtained from dissection of fully- shelled eggs in the oviduct. 63 fully shelled eggs from oviducts of females (the open squares) are considered to be accurate to within one day. Only those dates where error was apparently impossible were plotted in these figures. The same nests were checked again in 1967 which facilitated obtaining accurate egg- laying dates, often difficult when only one egg is laid. Extreme dates for the two years in cr istatella nests studied are 30 June (1966) and 14 June (1967), and 14 July (1966) and 3 July (1967); in pusilla, 24 June (1966) and 12 June (1967), and 5 July (1966) and 4 July (1967). One date in 1966 for psittacula shows 5 July (fully shelled egg in oviduct) and extremes in 1967 are 21 June and 7 July in nests studied. Bedard (personal correspondence) found fully shelled eggs in oviducts of cristatella in the Sevuokuk colony on 1 July 1964 and extremes of 29 June to 15 July 1965. In pusilla, he found extremes of 26 June to 9 July 1964 and 29 June to 21 July 1965, the late extreme for 1965 may possibly be a re-laying attempt (see Chapter II, C). Clutch commencement dates for these species are few in the literature; most reports are for eggs whose stage of incubation is unknown. In psittacula, Friedmann (1935) reported that Fisher collected seven eggs on Kodiak Island on 19 June 1884. Bailey (1948) found fresh eggs on the Diomede Islands on 3 July 1941 and stated (Bailey, 1925) that although they nest on King Island they had not yet begun to lay on 27 June 1921. There are eggs in the Thayer collection taken on Sledge Island on 22 August 1910 (Gabrielson and Lincoln, 1959), where Cade (1952) found a pair inhabiting a burrow on 9 June 1950, but no egg was present. Bent (1919) gives three dates for the "northern Bering Sea" as 20 July, 22 and 26 August. On the Pribilofs, egg dates range from 13 June 1890 to 1 July 1873 and 1 July 1914 (Preble and McAtee, 1923) and 8 June and 7, 16 July (Bent, 1919). On the Commander Islands "fresh eggs" have been found on 10 June (Kozlova, 195 7) . Bailey (1943) and Brooks (1953) reported egg- laying in cristatella started in early June on the Diomedes while J.J. Burns (personal correspondence) found eggs on 10 June but most commonly around 25 June on Little Diomede. On King Island, Burns (personal correspondence) found a freshly broken cristatella egg which was near hatching on 19 July 1963. Preble and McAtee (1923) reported the following egg dates from the Pribilof Islands: St. George Island, 19,. 20 June and 4 July 1873; St. Paul Island, 10 July 1895; Otter Island, 20,22 June 1884; Walrus Island, 16 June 1910. Brooks (1953) found pusilla eggs on Little Diomede Island on 25 June 1953 and Bent (1919) gave two egg dates for "northern Bering Sea" area as 20 June and 26 August, and in the Aleutian Islands, one egg date, 1 July. A. pusilla lays its eggs usually in June on the Pribilofs with dates for this locality ranging from 24 May 1890 to 2 July 1914 (Preble and McAtee, 1923). M.C. Thompson (personal correspondence) stated that pusilla were laying "and have been for over a week" on 13 June 1966 on St. George Island. Bedard (personal correspondence) observed adult Least Auklets carrying food to their chicks on St. Paul Island on 28 June 1967; this would give approximate egg dates of 29 or 30 May based on the 31 day incubation period for this species on St. Lawrence Island. Table 8 summarizes egg-laying in Parakeet, Crested and Least auklets on St. Lawrence Island in 1966 and 1967. Bedard (1967) presented estimated dates of hatching and fledging of cristatella and pusilla in the Sevuokuk colony in 1964, 1965 and 1966. From my data on incubation periods in these species (about 35 days in cristatella and 31 days in pusilla) Bedard's figures may be post• dated to obtain an approximate picture of egg-laying in 1964 and 1965; thus a comparison over four seasons is possible, 1964 to 1967. The two seasons in this study represent the extremes, 1966 being the latest and 1967 the earliest. Observations on psittacula chicks indicate a similarly late egg-laying in 1966 and direct 66 Legend for Table 8 Egg-laying in Parakeet, Crested, and Least auklets. Analysis from two seasons on St. Lawrence Island, Alaska. TABLE 8 C. psittacula Year 1966 1967 Sample size 1 13 Mean date July 5 June 23.2 Standard deviation 2.0 days Range 21 June - 7 July A. cristatella Year 1966 1967 Sample size 20 22 Mean date July 3.4 June 21.8 Standard deviation 4.1 days 6.3 days Range 30 June - 14 July 14 June - 3 July A. pusilla Year 1966 1967 Sample size 36 28 Mean date July 1.4 June 18.0 Standard deviation 3.1 days 4.4 days Range 24 June - 5 July 12 June - 4 July 67 observations on egg-laying in this species showed early egg-laying in 1967. I feel that there is a significant biological reason for this differential timing of egg- alying in these species in 1966 and 1967 and will discuss it in Chapter VI. b. The daily pattern of egg-laying The few data that I have on the time of day when auklets lay their eggs suggest that laying is concentrated during the early morning hours. Nest-sites were checked between 0200 and 0800 hr each morning during the egg- laying period. No eggs in nests studied appeared between 0800 and 0200 hr. However, since the majority of nest- sites were inaccessible it is possible that some eggs were laid during the latter period. Considering the circadian rhythm of the auklets in this colony (see Bedard, 1967), one might suspect laying to be concentrated during the early morning hours (as Drent (1961) and Winn (1950) suggested for Cepphus). The following observations strengthen this suggestion: At 0235 hr on 25 June 1967 walked along the snow on brow of Sevuokuk Mountain checking for auklet eggs laid on the snow. Returned by same route at 0305 hr and found one pusilla egg, laid between 0235 and 0305 hr. At 0410 hr on 18 June 1967 pusilla nest #16 was visited but found to be unoccupied. At 0440 hr I looked into this nest and found an adult with an egg. Using a temperature recorder placed in nests where the females were banded on Mandarte Island, British Columbia, Drent (1961:98) obtained two observations showing that Cepphus laid eggs between 0705 and 0730 hr and "almost certainly between 0810 and 0910 hr". C. The Clutch in Parakeet, Crested and Least Auklets a. Description of the eggs . The single egg of C. psittacula is generally ovate in shape with a tendency in some toward elliptical ovate forms. The egg is finely granulated, rough and without lustre. Its color is dull white with a very subtle bluish tinge; however, none was found to be "decidedly bluish, about the color of heron's eggs" (Bent, 1919:118). The single eggs of A. cristatella and A. pusilla are dull white and without lustre but do not show the bluish tinge or feel as rough as those of psittacula. Each species' eggs often become stained from moist earth on the nest floor as incubation progresses. Crested and Least auklet eggs vary in shape from ovate to pointed ovate. Table 9 gives dimensions of Parakeet Auklet eggs and table 10 gives those of Crested and Least on St. Lawrence Island; comparative measurements from the literature are also given. It is apparent that psittacula 69 Legend for Table 9 Dimensions of Parakeet Auklet eggs. TABLE 9 No. of Extremes Mean Locality Measurements (mm) (mm) Source Bering Sea area 33 58.0 x 33.5 54.3 x 37.3 Bent (1919) 5 7.5 x 40. 0. 51.5 x 37.0 52.5 x 33.0 Asian Seacoast ? 51.5 to 58.0 long ? Kozlova (1957) 33.0 to 40.0 wide St. Lawrence island 18 58.7 x 37.2 53.3 x 37.3 This study 53.0 x 39.5 50.0 x 39.5 51.4 x 33.4 70 Legend for Table 10 Dimensions of Crested and Least auklet eggs. TABLE 10 No. of Extremes Mean Source Locality Measurements (mm) (mm) CRESTED AUKLET Bering Sea 30 60. 0 x 41.0 54. 2 X 37. 9 Bent (1919) area 59.0 x 42.5 50. 0 x 38.5 55. 0 x 32.5 Asian Seacoast ? 5 0 to 60 long ? Kozlova (1957) 32.5 to 42.5 wide St. Lawrence 65 58.3 x 38.4 56. 8 X 37. 2 This study Island 53.4 x 38.9 50. 0 x 36.1 51.6 x 31.8 LEAST AUKLET Bering Sea 57 43. 0 x 28.5 39. 5 X 28. 5 Bent (1919) area 40. 0 x 33.5 33.5 x 29.0 40.0 x 27.0 Asian Seacoast p 33.5 to 43.0 long •> Kozlova (1957) 27.0 to 33.5 wide St. Lawrence 126 44.5 x 27.0 39. 8 X 28. 3 This .study Island 42. 8 x 32.9 35. 8 x 28.2 39.5 x 26.5 and cristatella eggs are indistinguishable from each other based on size, however, pusilla eggs are readily identified without observing the adult on the nest. Tables 11 and 12 record changes in weight of some alcid eggs during incubation and these egg-weights expressed as percentages of adult body-weights, respectively. The egg and adult weights of Alca, Uria, Cepphus and Fratercula arctica in table 11 are from Johnson (1944); the eggs weighed by Johnson irregardless of their stage in incubation, have been entered under the "fresh-egg" column for our purposes. It may be seen from table 12 that the weight of the egg in proportion to the body weight of the adult varies among these alcids, ranging from 9o7 percent in F. corniculata to 19.0 percent in pusilla for "fresh eggs". This is in agreement with the general trend of variation found within each family of birds, that is, for smaller species to have proportionately larger eggs (Heinroth, 1922). Lack (1967) showed that clutch size and the relative size of eggs in waterfowl are inversely related. He stated (p. 126) that "it is reasonable to suggest that the clutch size and the size of eggs have been evolved in relation to the average availability of food for the female around the time of laying". Lack also suggests (p. 126) "the female has limited food reserves which can be used to form either a few large 72 Legend for Table 11 Weights of fresh and pipped eggs in eight species of alcids. Data for Alca torda, Uria aalge, Cepphus grylle, and Fratercula arctica are from Johnson (1940). Data for F_. corniculata from Sealy, unpublished data. The value outside the parentheses is the mean value; the first number inside the parentheses is the sample size, the last two numbers are the extremes. Adult body-weights included for comparison. TABLE 11 Species Fresh Eggs* Pipped Eggs * Adults Alca torda 85.4 (38:73.5-100) 686 (7:608-740) Ur ia aalge 103.4 (15:83-117) 964.7 (89:815-1150) Cepphus grylle 49. 2 (23:42-65) 419 (69: ) Cy ch1orrhynchu s 37.5 (3 :36. 6-39. 1) 34. 8 (4:28.4-34.5) 280.6 (17:224. 7-316.2) ps ittacula Aethia cristatella 40.5 (10:37.6-42.8) 32.8 (3 :31. 2-33.6) 286.6 (192:25 0.5-324.6) Aethia pusilla 17.5 (14:14.2-19.8) 13.7 (7:12.3-14.9) 92. 0 (125 :70. 2-113.1) Fratercula arctica 55. 9 (30:54.5-73. 2) 476.1 (29:407-542) F. corniculata 57.1 (2 :56. 1-58. 1) 587.1 (15:499.6-690.9) * Weights in grams 73 Legend for Table 12 Egg-weight in relation to body-weight in some alcids (weights in grams). Egg and body-weights of Alca torda, Uria aalge, Cepphus grylle, and Fratercula arctica are from Johnson (1940) , the weights of F_. corniculata are from Sealy, unpublished data. Johnson's egg-weights are considered to be fresh eggs. TABLE 12 Species Fresh Eggs Pipped Eggs Alca torda 12. 4% -- •- Uria aalge 10. 1% — •-• Cepphus grylle 11. 1% — •- Cychlorrhynchus psittacula 13. 3% 12. 4% Aethia cristatella 14. 2% 11. 5% Aethia pusilla 19. 0% 14. 6% Fratercula arctica 11. 1% '-- •- F. corniculata 9. 1% — •— 74 eggs or more smaller ones". Examination of the shape and coloration of aleid eggs relative to their nesting habits reveals certain apparent adaptive features. The egg-form varies.from elliptical in puffins, ovate in auklets to pyriform in murres. Belopolskii (1961) and Tuck (1961) demonstrated the adaptive significance of pyriform-shaped eggs of murres which are laid on open, rocky ledges. Here a dislodged egg rotates on its axis in a manner governed by its state of incubation (Tuck, 1961) and therefore curtails the chance of rolling off the smooth surface. Puffin and auklet eggs, which are usually laid in burrows and crevices, respectively, are in less danger of rolling. The color of auk eggs also varies apparently according to the type of nest-site utilized by the particular species. Those which nest in open or semi-open situations have cryptically colored eggs, e.g., the extinct Pinguinus, Alca, Ur ia spp., Cepphus, and those nesting in concealed situations, e.g., Plautus, Cychlorrhynchus, Aethia, are dull white or bluish. Belopolskii (1961) stated that faint markings on some puffin eggs, which are laid in burrows, are superficial. An exception are the spotted eggs of Endomychura and Synthliboramphus, which are also laid in burrows. This may indicate these latter two species acquired the burrow-nesting habit late in the history of the Alcidae, however, Dawson (1920:14) stated that the submerged markings on the eggs of these species "indicate a considerable antiquity, but there is no evidence of actual loss of color through troglodytic habit, unless, possibly in the lighter ground shades of S. antiquus". Tschanz (1959) demonstrated that the capacity to learn the individual characteristics of an egg is well developed in Common Murres. He found that they have a strong inhibition against retrieving an egg of another bird, unless it closely resembles their own. b. Clutch size Cychlorrhynchus, A. cristatella and A. pusilla lay one egg to a clutch. There is one record in the literature of Cychlorrhynchus and Aethia laying "two unmarked eggs (Storer, 1945:455) but this is apparently in error for he earlier stated (p. 453) that "In shape of the hind limb and pelvis and the single white, ovate egg the Auklets (Ptychoramphus, Cychlorrhynchus and Aethia) form a very homogeneous group". One-egg clutches is the general rule in the Alcidae, except Cepphus (Wynne-Edwards, 1955) where two eggs are most common (Drent, 1965), Endomychura (Bent, 1919) and Synthliboramphus (Drent and Guiguet, 1961). One-egg clutches have been recorded in Cepphus (Drent, 1965; Thoresen and Booth, 1958; Winn, 1950) as well as three-egg clutches (Winri, 1950), but the latter is considered by Drent (1965) to be probably the work of two females or possibly replacement laying. Rare instances of two-egg clutches in puffins (F. arctica) have been reported (Kaftanowskii, 1951) and Alca (Fisher and Lockley, 1954). Storer (1945) described Cerorhinca, Fratercula and Lunda as laying two eggs which are usually faintly marked. According to Bent (1919), Dawson and Bowles (1909), Kozlova (195 7) and Richardson (1961) , Cerorhinca lays only one egg, however, "Apparently a second egg may be laid if the first is destroyed (Richardson, 1961:463). Lunda also lays only one egg (Bent, 1919; Kozlova, 1957; Drent and Guiguet, 1961; Drent, et a_l, 1964) . c. Replacement of lost or destroyed eggs It is known that most birds are capable of laying successive clutches, provided the first clutch is lost soon after laying (Sleptsov, 1948). The family Alcidae is no exception for repeat clutches have been reported for most auks studied. Despite adequate sampling and examination of ovaries, Bedard (1967) observed only one apparent instance (A. pusilla in 1966) of repeat laying in Cychlorrhynchus and Aethia. In 1967 I observed an irrefutable case of renesting in Cychlorrhynchus and two possible instances of renesting in each of A. cristatella and A. pusilla. 77 On 26 June 1967 an adult Parakeet Auklet was captured by hand in an empty nest-site on Sevuokuk Mountain and banded no. 514-38109; a fully shelled egg in its oviduct could be felt. Oh 27 June the egg was present and on 29 June it was accidentally broken by me and removed. On 4 August this nest was revisited and the same female was found incubating an egg; it hatched on 18 August but the chick was killed by a microtine rodent by 19 August. I do not know if the same male was involved in this renesting; however, the maintenance of the pair-bond throughout the breeding season and probably over a number of years would suggest that the same male was involved. Considering the hatching date of the second egg, 18 August, and the 35-day incubation period of Cychlorrhynchus on St. Lawrence Island, the second egg must have been laid about 14 July or about 16 days after the first one was destroyed. On 17 June in pusilla nest #5, an egg was being incubated in about two cm of water. On 14 July the original egg was still present in the nest but pushed aside, and an adult was incubating another egg. This egg was being incubated on 20 July but was abandoned-by 25 July; it was addled. Neither adult from nest #5 was marked making it impossible to be sure renesting occurred. On 17 July a pus ilia nest containing two eggs, one being incubated in about one cm of water and the other', broken and pushed aside, was found. The egg being incubated showed no 78 embryonal development and the "original" egg was addled. The adult female was collected and its ovaries were dissected and examined; only one postovulated follicle was evident, a second or previously ovulated follicle if present, was not discernable. On 26 June the egg in cristatella nest #36 was laid; on 20 July it was found that egg #36 was pushed aside and a second egg was being incubated. Neither adult in nest #36 was banded. Desertion occurred about 25 July and neither egg showed embryonal development. Run-off water was deemed the cause of the first egg being abandoned. A second possible renesting attempt in cristatella was found on 5 August on the west slope of Sevuokuk Mountain; two eggs were present, one was pushed aside and the other was being incubated. The egg being incubated contained a we11-developed embryo but the "first" egg was addled. It appears, although the evidence regarding cristatella and pusilla is circumstantial, that renesting may occur in these auklets, particularly in an early season. The fact that renesting in psittacula nest #6 is irrefutable may support the possibility of its occurrence in Aethia. The adaptive significance of renesting in auklets in an early season like 1967 is apparent when snow-melt is considered. Evidentally the cause of egg 79 rejection in the above pusilla and one cristatella nests was submergence in run-off water which flows down the slope in small streamlets among the rocks when snow melts. As this brow-snow continued to melt it produced continuous run-off which no doubt found.its way to numerous auklet nests. It is probable that auklets can successfully hatch an egg that has been temporarily submerged in water, as has been found in Brant (Barry, 1962), but continued submergence in cold water would probably kill an embryo. The temperature inside a pus ilia egg which was being incubated in water on 17 July 1967 (the second pusilla nest mentioned above) was 11.2°C compared to about 38°C in eggs under "normal" incubation. In a. later season the brow-snow melts shortly after egg-laying commences throughout the colony and auklet eggs are exposed to minimal run-off water. Thus, loss of eggs in an early season may be compensated for by abandoning the first egg and laying a second. Drent (1965) found in C. columba that no replacements were noted if only one of a two-clutch was lost, but if the entire clutch was lost a repeat clutch appeared in approximately 13 days in about half of the cases. For C. grylle Winn (1950) recorded two repeat clutches in 15 days or less and Uspenski (1958) recorded one 18-day interval. For C. columba Thoresen and Booth (1958) estimated two cases of 18 days. Alca, Ur ia spp. 80 and Fratercula arctica are also known to renest if their eggs are removed early in incubation (Paluden, 1947; Uspenski, 1958; Tschanz,. 1959; Kartaschew, 1960) . D. Incubation in Parakeet, Crested and Least Auklets a. Incubation periods in auklets Assuming normal, undisturbed incubation, the average time interval between laying an egg and emergence of the young bird represents the incubation period (Heinroth, 1922). However, according to Tucker (1943) and Swanberg (1950), a bird can sit on an egg without heating it, thus, for practical purposes a species' incubation period may be defined as the interval between laying the last egg of a clutch and hatching of the last egg (assuming that all eggs hatch). Observations on auklets on St. Lawrence Island showed that adults continually sat on the one-egg clutches immediately after they were laid but these observations are not accompanied by temperature data to show exactly when' the eggs were first heated. For purposes of this study it is assumed that eggs in undisturbed nests are heated from the time they were laid until they hatched. Drent (1965) emphasized the importance of stating clearly the obvious intervals between laying and hatching. The 24-hour photoperiod which prevails throughout most of the breeding season on this Island enabled laying dates obtained by direct observation (as opposed to those obtained Legend for Table 13 Period from laying egg until the chick is free of the shell in C. psittacula, A. cristatella, and A. pusilla. Data from 1966 and 1967 combined. TABLE 13 C. psittacula cristatella A. pusilla 35 days 3 34 days 2 28 days 1 36 days 1 36 days 2 29 days 6 3 7 days 2 32 days 4 33 days 1 34 days 1 36 days 2 Number 6 15 of cases 4 35.6 days 31.. 2 days Mean 35.2 days 82 by dissection of egg-laying females) to be accurate to within about six hours. Nest-sites were checked between 0200 and 0800 hr each morning during the egg-laying period, eggs present on the second visit of the morning were counted as being laid on that day. The hatching date of each chick is accurate to the nearest day, the nests being checked in the same sequence each day between 1000 and 1400 hr; the maximum error in the determination of the incubation periods of these auklets is thus about 30 hours but in most cases is probably less than 24 hours. Data from four nests of psittacula in 1967, six nests of cristatella and 15 nests of pusilla in 1966 and 1967 are shown in table 13. My hatching data may be summarized as follows: the interval between the occurrence of the first cracks on the egg and emergence of the chick from the shell was variable. This time interval in four eggs of psittacula in 1967 was 2 to 4 days (mean, 3.0 days), in 8 eggs of cristatella in both seasons was 2 to 6 days (mean, 3.3 days), and in 27 eggs of pusilla in both seasons was 1 to 7 days (mean, 3.2 days). About two days prior to hatching in psittacula and cristatella and one day in pus ilia a definite hole (the "pipped" condition) appeared on the egg. The voice of the unhatched chick was a hoarse cheeping which, according to Drent (1961), is no doubt important in preparing the parents for feeding, etc. 83 to come. He also stated that the chicks' voices may function directly in ensuring continuous incubation, since the pipped egg must not dry out, and further possibly plays a role along with tactile stimuli in altering the stance of the adults on the eggs. There are no incubation periods of C. psittacula, A. cristatella and A. pusilla in the literature. Incubation periods of other plankton-feeding alcids are 24 days for Plautus (Faber _in Uspenski, 1958) and "at least 37 days" in Ptychoramphus (Thoresen, 1964). b. Incubation temperatures in Parakeet, Crested and Least auklets From 20 July to 12 September 1966 ambient temperatures in the Sevuokuk colony and a continuous recording of air temperatures in a cristatella nest-site were obtained. In 1967 ambient temperatures were recorded from 6 June to 7 September and sporadic continuous recordings on the floor of a pusilla nest were obtained. After 15 July 1967 a telethermometer was available and was used in thermoregulatory studies (reported in Chapter III) . Several "spot" measurements of nest-site air temperatures in each species were obtained during the thermoregulation studies and are shown in table 24. 1. Nest temperatures Since inclement weather, particularly chilling 84 winds, is a common feature of St. Lawrence Island's summer climate, it was deemed important to see what stabilizing and sheltering effects if any were afforded by the nest micro-environment, among the interstices of the rocks. Figure 16 compares the air temperature in a cristatella nest-site to the ambient temperatures from about 20 July to 13 September 1966 (table 3) It is seen that temperatures in this nest-site were fairly stable despite higher or lower ambient temperatures. This nest- site never reached the general minimum, a fact possibly explained by the slow cooling of the surrounding rock (Drent, 1961). The nest temperature was greater than the ambient temperature throughout most of the period of measurement. This is most likely due to the chilling effect of the ocean on the air above the slope (Trewartha, 1954), in this case at the 8m contour. The chilling effects of this air inside the nests is possibly great but was not measured. Table 14 shows sporadic temperature recordings in one pusilla nest at the 55m contour on the northeast slope of Sevuokuk Mountain and one pus ilia nest on the west slope of the Mountain at the 100m contour. Probes were placed on the nest floor, prior to egg-laying in the known nest-site on the west slope and after the egg had been laid in the northeast slope nest-site, in a manner whereby the probe was not influenced by the adult. The higher nest floor temperatures obtained during the 85 Legend for Figure 16 Mean maximum and minimum air temperatures in a nest- site of A. cristatella during the latter half of the breeding season, 1966, St. Lawrence Island. Mean maximum and minimum ambient temperatures for the same period are also given. Temperatures recorded at the 8m contour on the slope. I 8-14 15-21 22-28 29-31 1-7 8-14 15-21 22-28 29-31 1-7 8-14 15-21 July | August I September nest temperature @ @ air temperature Legend for Table 14 Temperatures inside the nest-site of Aethia pusilla, St. Lawrence Island, Alaska, 1967. Temperatures measured in °C. TABLE 14 Mean Mean Period Maximum Minimum . x Temperature June 2-8 * 14.7 10.0 12.4 9-11* 16.7 11.7 14.2 July 21-28** 8.3 7.2 7.7 August 11-19** 5.2 6.0 5.6 * One nest-site on west slope of Sevuokuk Mountain ** One nest-site on northeast slope of Sevuokuk Mountain 87 two periods in June (June 2-8, 9-11) may be accounted for by the fact this nest was located on the west slope of the Mountain where direct sunlight, which is more prevalent in this month, would apparently be felt. The July and August recordings are from the northeast slope which is generally shaded. The lower nest floor temperatures obtained during the latter readings as compared to ambient temperatures from the same slope may be due to the damp soil on the nest floor. It appears that auklets' nest-temperature regimes have the following significance: (1) the eggs and chicks are subjected to low but stable nest micro-environmental temperatures despite wide ranges of ambient temperatures and chilling winds, (2) the nest-site temperatures do not reach the minimum ambient temperatures, and (3) nest-site temperatures are greater than the air temperatures above the slope possibly due to the absence of the chilling factor from the ocean. 2. Brood patches and brood patch temperatures Two brood patches are present on C. psittacula, A. Cristatella and A. pusilla; each is located on the flanks under each wing. The average brood patch .dimensions in five psittacula was 44 x 27mm, in four cristatella 43 x 27mm, and six pusilla 25 x 15mm. According to Bailey (1952) and Kozlova (1957) brood patches are present in all alcids. The varying number and location of these brood patches in alcids has been studied in several species (see Payne, 1966). The absence of a brood patch or patches in Ptychoramphus aleutica and its apparent significance has been discussed by Payne (1966). I feel that observations gained in the present study do not fully support Payne's arguments. Payne stated (p. 209) that "The absence of a brood patch in Cassin Auklets may be related to the small size of these sea-birds. The body surface-volume ratio is larger in small birds, and the presence of a relatively large unfeathered area on the body might bring on excess loss of heat to the cold ocean". He later pointed out that only those alcids reported having brood patches, except for Plautus, are larger than Ptychor amphu s. The presence of brood patches in Aethia pusilla, which weighs about 90g compared to about 172g for Ptychor amphu s (Thoresen, 1964), appears to support this objection to Payne, at least regarding this point. It is also interesting to note that the temperature of the Bering Sea in summer in the vicinity of St. Lawrence Island varies around 0-10°C (Goodman, et al, 1942; this study) while the ocean temperature near South Farallon Island, California (where Payne's work was done), is about 11-15°C in the summer (Sverdrup, et al, 1942). The average body temperature of six Ptychoramphus was 41.5°C and the temperature of the skin 89 beneath their wings was 39.7°C (Payne, 1966). Similar measurements of 13 pusilla were 40.7°C and 38.0°C (table 15), respectively, on St. Lawrence Island. Drent (1965), working with Cepphus, obtained data on temperature at the interface between the upper egg surface and brood patch (termed "incubation temperature" following Farner, 1958) which showed that the definitive level of this temperature is not reached until the second egg has been laid, or soon thereafter. By using a telethermometer and probes taped to the shell of the egg in such a way as to be in contact with the adult's brood patch, he was able to secure these temperature readings. In the present study only "spot" measurements of brood patch temperatures in adult auklets near the end of incubation were obtained. The results, presented with body temperatures for comparison in table 15,.cannot be accurately compared to Drent's data for his brood patch temperatures were measured directly from adults sitting on and presumably applying heat to their eggs. My readings measured within 15 minutes after removing the auklets from their nests, involved excited, "handled" birds where bias is imminent (Udvardy, 1953). Howell and Bartholomew (1961), however, used this latter method with apparent success in Diomedea. Drent (1961) summarized the role of incubation patches in birds, emphasizing their special modification Legend for Table 15 Temperatures of the fully developed brood patch compared to the body temperatures in auklets. Body temperatures are esophageal and measured in °C. TABLE 15 Sample Description Size Mean C. psittacula incubating egg 9 40.4 C. psittacula brood patch 12 36. 9 A. cristatella incubating egg 2 40. 1 A. cristatella brood patch 3 38. 1 A. pusilla incubating egg 13 40. 7 Pusilla brood patch 12 38. 0 91 to apply temperatures to egg-surfaces that is almost as high as the parent's body temperature. An examination of table 15 reveals that the brood patch temperature of psittacula is about 4°C less than the body temperature and about 1-2°C lower in cristatella and pusilla. Table 16 summarizes available information on brood patch and body temperatures in alcids. Considering tables 15 and 16, it is seen that auklet body temperatures on St. Lawrence Island are comparable to each other and to within one or two degrees of body temperatures of alcids in other localities. The brood patch temperatures of auklets are lower than those of other alcids except for Cepphus grylle. The three readings for F_. corniculata were obtained in an identical manner to that of the auklets, but the techniques involved with the other species, except C. columba, are unknown; it is thus unwise to base conclusions on these differences. c. Incubation rhythm in Parakeet, Crested and Least auklets The few available reports in the literature indicate that both sexes in Parakeet, Crested and Least auklets incubate (Bedard, 1967, for all three species; Bent, 1919, and Gabrielson and Lincoln, 1959, for cristatella; Gabrielson and Lincoln, 1959, for pusilla), but notes on attentiveness, incubation shifts and the time when steady incubation actually sets in are lacking. Except 92 Legend for Table 16 Temperatures of the fully developed brood patch compared to body temperature in some alcids. Temperatures are o measured in C. TABLE 16 Brood Patch Body Species Temperature Temperature Author ity Ur ia lomv ia 41. 0 39.0 Kartaschew (1960) U. lomvia 41.5 41.5 Uspenski (1958) Cepphus grylle 35 - 37 — Kartaschew (1960) C. columba 40. 6 39.4 Drent (1965); rectal* Fratercula arctica 42. 3 42. 3 Lockley (1953); rectal* F. corniculata** 40. 1 38. 0 Sealy (unpublished data) ; esophageal* Method of obtaining body temperature Three in sample for Bedard, the knowledge that both sexes in these auklets incubate appears to be unqualified, possibly based on the pretext that both sexes in many other alcids are known to share incubation duties. The presence of brood patches on male auklets is indicative of their participation in incubation, however, the sexes are not sexually dimorphic with respect to external morphology, and it is necessary to capture and dissect incubating adults before a set incubation pattern, if one could be determined, exists. The concealed nature of the nest-sites precluded direct observations of incubation and a temperature recorder was not available to overcome this difficulty, or to determine the exact onset of incubation. Five incubating auklets, three cr istatella and two pus ilia, were collected during both the evening and mid-day periods in the incubation stage; dissection revealed males and females incubate during either period. The sample is too small for a pattern, if one exists, concerning the role of the sexes in incubation to be discerned. In the literature, so-called evening and morning shifts in incubation have been described, the changing of these shifts providing a spectacular bird display (described in Bent, 1919; Gabrielson and Lincoln, 1959). According to Bedard (personal correspondence) the change of.shifts is not the cause of the spectacular display observed by the former authors; he feels that .this change is related to their circadian rhythm and is independent of incubating partners. 94 CHAPTER III. The Chick Stage A discussion of the manner of raising young within the auk family is given by Drent (1965). He stated (p. 134) that auks raise their young "by three drastically different methods". The first group includes Endomychura and Synth1iboramphus whose chicks scramble to sea within a couple of days after hatching. In the second group, consisting of the open-nesters, Uria spp., and the semi- open-nester, Alca, the chicks are fed at the nest-site for about 20 days before they go to sea. In the last group the chicks are fed at the nest-sites until they are fully developed or about one month of age before fluttering out to sea to assume an independent existence. Making up this third group are many nocturnal and diurnal burrow-nesters, e.g., Cepphus, Ptychoramphus, Cerorhinca, Fratercula, Lunda, and the crevice and cliff-nesters, e.g., Plautus, Cychlorrhynchus, Aethia. A. The Nestling Period in Auklets The nestling periods of C. psittacula, A. cr istatella and A. pusilla have not been previously determined. Bent (1919) described young Crested Auklets as remaining in the nesting cavity until they are fully developed and able to fly. Similar observations on this 95 species were made by Kozlova (1957). Table 17 summarizes the nestling periods of psittacula, cr istatella and pusilla on St. Lawrence Island. In each case the chick was last seen in the nest-site between 1300 and 1800 hr on the previous afternoon, and as is shown"later most of the chicks departed for sea in the early morning (of the day given in table 17). It becomes apparent upon examination of table 17 that the average time spent in the nest by the chicks may be longer or shorter from one year to the next. Before considering possible causes of shortening the nestling period in different years it is necessary to examine the growth of chicks and the factors controlling growth and its rate; this will be done later in this chapter and summarized in Chapter VI. There is considerable evidence to show that there is a shorter nestling period in arctic-breeding birds as compared to temperate or tropic-breeders (Armstrong, 1954; Irving, 1960; Oakeson, 1954; and others). In the Alcidae only Ptychor amphu s may be compared to the Bering Sea auklets regarding the duration of their nestling periods. Ptychor amphu s, whose size is intermediate between the smaller A. pusilla and larger A. cristatella and C. psittacula, has a nestling period of 41 to 50 days in southern Oregon and northern California (Thoresen, 1964). 96 Legend for Table 17 Nestling periods of Parakeet, Crested and Least auklets on St. Lawrence Island, Alaska, in 1966 and 1967. TABLE 17 Nestling Period 1966 1967 1966 and 1967 Parakeet Auklet 34 days — 1 — 35 days — 3 — 36 days — 1 — 37 days — 1 — MEAN 35.3 days — — Crested Auklet 30 days 2 — 2 32 days 1 — 1 33 days — 1 1 34 days 3 6 9 35 days 1 2 3 MEAN 32.0 days 34.1 days 33.5 days Least Auklet 25 days 1 — 1 27 days 1 — 1 28 days 3 1 4 29 days 3 2 5 30 days 1 4 5 31 days 2 1 3 32 days 1 — 1 MEAN 28.9 days 29.6 days 29.2 days 97 B. Feeding Habits of Auklets a. Prey species In the manner characteristic of plankton-feeding (as distinct from fish-feeding) alcids, Parakeet, Crested and Least auklet parents carry food to their chicks in a neck-pouch, a special diverticulum of the buccal cavity (Bedard, 1967). The parents carrying food to their chicks are easily recognized by the swollen condition of the neck. The food habits of these auklets were extensively studied on St. Lawrence Island by Bedard (1967) in the summers of 1964, 1965 and 1966 and a functional interpretation of the existing feeding patterns was presented. In 1966 I assisted Bedard in collecting birds on their feeding grounds from May to July; during the latter part of July, 1967, food samples were obtained from adults on the nesting slope during the mid-day feeding period, approximately two hours between 1400 and 1600 hr. Inclement weather immediately prior to hatching in 1967 prevented collecting birds on their feeding grounds at sea at this time. Sampling techniques, analytical techniques, sources of error, etc, have been discussed by Bedard (1967:33-50), and will not be repeated. In this section Bedard1s findings regarding the food items of adult auklets and that which is brought to the chicks, that is, samples collected from adults foraging at sea 98 during the pre-egg and incubation stages and parents on the nesting slope during the chick-rearing period are summarized. According to Bedard, preliminary examination of food samples revealed no difference between the diet of adult birds themselves and the diet they selected for their chicks. The apparent significance of the diet changes that occurs throughout the breeding season in Aethia spp. but not in Cychlorrhynchus will be discussed in Chapter VI. Figure 17 (figure 20 of Bedard, 1967) presents prey items and their relative importance in the early summer diet of A. cristatella and A. pusilla (food in their gullets). Figure 18 (figure 21 of Bedard, 1967) summarizes prey items and their relative importance in the food brought to the chicks during August and September (food in neck-pouch) for Aethia spp. and Cychlorrhynchus. Bedard sorted the food items which appear in these figures according to type and size. The size was determined on overall length (tip of rostrum or cephalothorax to tip of telson), excluding long appendages such as the antennae of some gammarids. The size categories were as follows: Size I (0.1 to 7.0mm); Size II (7.1 to 15.0mm); Size III (15.1mm and over). The following summary of the seasonal feeding patterns of Cychlorrhynchus and Aethia spp. are from Bedard (1967:155-156): 99 Legend for Figure 17 Relative importance (in volume) of various prey- items of various size categories in the early summer diet of Aethia pusilla and Aethia cristatella (food in gullets). Samples from 1964, 1965 and 1966 and both sexes combined. From, Bedard (1967:46, figure 20). Code for size categories discussed in text of the present thesis. i n m Size categories 100 Legend for Figure 18 Relative importance (in volume) of various prey types of various size categories in the food brought to the chick during August and September (food in neck-pouches). Samples from 1964, 1965 and 1966 and both sexes combined. From, Bedard (1967:47, figure 21). Code for size categories as in figure 17. Relative importance (% of total volume) — ro cn o o o o O o O Calanus finmarchicus Calanus cristatus Eucalanus bungii HYPERIIDEA • EUPHAUSIACEA • MYSIDACEA > o CD CARIDEA 1 —«- a 101 (1) The two species of Aethia exhibit rather similar patterns of dependence upon the food source; both show during early summer a diversified diet consisting of mysids, hyperiids, gammarids, etc., but restrict themselves largely to one principal prey during the chick-rearing period. Then, A. pusilla eats mostly Calanus finmarchicus while, A. cristatella eats Thysanoessa spp. (2) This sharp reversal to monophagy during the chick-rearing period apparently reflects a sudden increase in the availability of these prey items in the surrounding waters. Available evidence indicates that the food carried to the chick does not differ from the food used by adult birds themselves. In all years, hatching coincided closely with the appearance of these prey items in the environment and it is believed that the breeding season has been adjusted to their cyclical abundance. (3) Cychlorrhynchus occupies a slightly higher position in the trophic pyramid. This is indicated by its eating a higher proportion of carnivorous zooplankton (such as hyperiids, fish, pteropods, cephalopods, etc.) than either species of Aethia. (4) Although sampling is less adequate in the case of Cychlorrhynchus, there is no sign that this species reverts to one principal type of prey during the period of rearing their chicks. They seem rather to show a 102 preference for numerous types of prey during that period. C. Growth of Chicks Growth of body weight and certain body parts was studied in the Crested and Least auklets in both seasons and in Parakeet Auklets in 1967. There are no previous studies of growth in these species. Tables 18, 19 and 20, and figures 19 and 20 summarize body weight records for each species obtained during the study. The number of chicks of known hatching date in v. accessible nests did not remain constant during the study due in part to microtine predation; also, many chicks, particularly cristatella, became impossible to reach in the nest^-sites as they became older and more aware of danger for they often retreated to the inner recesses of the rock crevices out of reach. Table 21 compares weights and measurements of the outer primary, tarsus, culmen and first rectrix in young auklets at hatching (day 0) and point of departure with those of the adults. In each case the body weight of young at the time of departure represents my last record for that chick - it had departed by the time of my last nest-check the following day. When young auklets leave the nest to take up apparently independent existences, they have attained, on the average, 79.3%, 79.6% and 87.5% of the adult body weights in psittacula, cristatella Legend for Table 18 Growth in Parakeet Auklets, St. Lawrence Island, 1967. TABLE 18 Age in Mean Range Days Sample Size (g) (g) 0 4 28. 1 25.6-34.4 1 4 32. 9 27.5-38.9 2 4 39.5 31.9-45.5 3 5 45. 2 37.9-51.2 4 6 56.5 48.2-62.3 5 6 63.0 52.4-71.2 6 6 73. 7 61.7-79.8 7 5 87.4 68.4-114.3 8 6 94.8 _ 73.3-108.7 9 6 100.3 84.7-118.9 10 6 108. 2 93.2-141.2 11 6 117. 7 94.4-149.2 12 6 127. 0 111.1-153.3 13 6 140. 6 110.4-169.4 14 6 154.8 134.5-182.6 15 5 166.5 152.2-195.8 16 6 175. 2 153.3-220.6 17 5 184. 7 169.2-214.1 18 5 191.3 171.4-217.1 19 6 191. 7 180.1-214.2 20 6 195.4 183.4-212.9 21 6 203. 2 182.7-234.7 22 6 207.5 185.1-250.9 23 5 206. 8 187.4-259.4 24 6 215. 7 169.7-263.4 25 4 222. 0 191.1-271. 7 26 4 249.0 207.2-276.6 27 5 237.9 205.5-265.4 28 5 249.1 230.1-278.9 29 4 251. 0 232.7-280.9 30 4 238. 7 225.1-251.2 31 4 238.4 217.7-256.7 32 4 219.2 203.6-244.4 33 4 227. 3 205.0-248.6 34 5 236. 1 206.1-264.4 35 2 218. 1 194.1-242.1 36 1 241.1 37 1 235. 6 104 Legend for Table 19 Growth in the Crested Auklets, St. Lawrence Island. Data for 1966 and 1967 combined. TABLE 19 Age in Mean Range Days Sample Size (g) (g) 0 13 29.5 24.1-34. .1 1 12 33. 9 30.1-35.8 2 10 39.6 35.3-43.0 3 12 48. 6 40.6-56.4 4 14 55.1 48.4-61.0 5 13 63. 9 57.6-74.2 6 15 74. 2 54.9-83.4 7 14 83.4 70.8-94.5 8 15 93.6 83.3-102.4 9 14 107.6 91.6-113.5 10 12 120. 0 105.6-135.6 11 12 133. 8 117.1-142.3 12 12 148.4 139.8-160.0 13 13 159. 7 149.4-175.1 14 12 172.4 157.8-185.6 15 14 182. 0 175.4-210.6 16 12 186. 8 166.2-198.7 17 13 194. 2 159.5-217.1 18 11 207. 2 155.6-238.8 19 12 214.4 170.8-237.1 20 12 221. 3 186.2-253.6 21 13 238. 2 196.6-271.8 22 11 250.0 207.6-290.6 23 12 240.8 215.7-274.1 24 12 256.9 221.7-279.7 25 10 249. 3 211.2-268.7 26 12 252. 3 222.8-287.1 27 12 260. 2 203.7-294.3 28 11 254.4 214.3-295.6 29 11 254. 3 209.3-284.1 30 9 252. 1 238.8-281.6 31 9 240.6 225.3-262.5 32 7 233. 5 217.3-248.4 33 7 218. 9 203.6-241.7 34 3 221.1 212.2-235.6 35 1 215.6 105 Legend for Table 20 Growth in Least Auklets on St. Lawrence Island, Alaska. Data for 1966 and 1967 presented separately. TABLE 20 1966 1967 Age in Sample Mean Range Age in Sample Mean Range Days Size (g) (q) Days Size (q) (q) 0 17 12. 3 9.5-14.6 0 15 12.4 9.9-15.9 1 18 15.4 10.9-18.1 1 16 14.5 10.9-17.9 2 17 18. 1 14.8-21.1 2 14 17.5 11.2-20.8 3 14 21. 9 14.2-27.9 3 14 21. 8 16.1-27.7 4 15 26. 1 14.9-32.6 4 13 26.4 22.0-27.7 5 17 29. 2 16.2-36.5 5 11 29. 1 23.7-33.2 6 17 34.4 18.5-47.3 6 11 35. 0 29.3-45.2 7 13 39. 3 27.6-56.2 7 10 40. 0 31.7-51.9 8 12 41. 2 26.7-56.2 8 10 46.1 35.8-55.2 9 15 45. 9 26.4-59.3 9 7 50.3 39. 1-57. 1 10 14 51. 8 30.2-76.4 10 8 57.2 47.6-62.9 11 13 54. 8 31.1-69.7 11 6 58. 9 51.7-67.8 12 14 59. 3 38.9-75.1 12 10 62. 7 53.9-71.3 13 14 65. 8 40.6-79.5 13 9 67. 7 57.4-76.6 14 .14 68.0 43.2-79.6 14 10 71. 7 63.0-78.9 15 13 73. 0 55.6-84.0 15 9 74. 7 69.2-82.2 16 12 74.1 52.7-92.9 16 8 79. 0 69.8-88.9 17 13 82. 6 64.4-101.4 17 7 81.4 73.1-86.4 18 13 ' 81. 3 62.7-97.2 18 6 84. 8 77.2-89.6 19 14 85.5 68.1-109.8 19 6 86,5 77,2-91,3 20 13 89.8 72.5-109.8 20 8 85.3 79.5=94.1 21 12 89.0 71.7-114.2 21 8 87. 0 79.4-95.6 22 13 89.8 72.5-109.8 22 7 85. 2 77.4-92.6 23 13 90.0 64.0-108.2 23 7 84.4 79.2-91.2 24 12 92. 3 66.3-111.4 24 8 84..2 79.5-96.9 25 10 94. 7 78.9-110.2 25 7 86.8 74.4-95.2 26 11 89.3 73.8-106.8 26 8 85. 2 73.9-101.1 27 9 88. 9 64.1-105.5 27 7 82. 6 73.8-91.1 28 7 87. 2 74.5-102.6 28 6 78. 0 70.8-84.3 29 4 89.6 82.2-97.6 29 5 78.4 70.5-83.1 30 3 88.1 84.8-91.7 30 1 81. 2 31 1 88. 2 106 Legend for Table 21 Body-weights and measurements of young auklets at hatching and at time of sea-going, St. Lawrence Island, Alaska. Weights and measurements are for 1966 and 1967 combined. The number outside the parentheses is the mean value; the number inside the parentheses is the sample size followed by the extreme values. Adult body-weights and measurements are included for comparison. TABLE 21 At Hatching At Sea-going Adults _C. psittacula weight (g) 28.1 (4:25. 6-34.4) 222.6 (6:194.1-259.1) 280.6 (17:224. 7-316. 2) outer primary (mm) 65.3 (6:61.1-68.1) 84. 0 (3 :81.1-85. 8) tarsus (mm) 17. 9 (4:17. 0-18. 9) 27.2 (4:23.7-33.2) 29.6 (3 :29. 2-30.6) culmen (mm) 8.6 (5:7. 9-8.8) 13.3 (4:13.1-13.6) 14.2 (3:13.2-15.7) #1 rectrix (mm) 27.6 (6:25.1-31.3) 36. 1 (3 :31.5-39.3) A. cristatella weight (g) 29.3 (13:24.1-34.1) 228. 2 (15 .-203.6-251. 1) 286.6 (192:250.5-324.6) outer primary (mm) 63. 8 (14:58. 7-70. 1) 75.5 (5 :74.6-76.8) tarsus (mm) 16.9(9:15.6-18.9) 29.4(11:27.6-30.7) 32.7 (11:30.3-36.1) culmen (mm) 7.6 (10:7.3-8.2). 10.1 (14:10.7-11.6) •12.0(9:10.6-13.5) #1 rectrix 25.3 (5 :24.8-27.3) 31.7(5 :27.6-34.4) A. pusilla weight (g) 12.6(22:9.9-15.9) 80.5 (25:64.1-101.6) 92. 0 (125 :70.2-113. 1) outer primary (mm) 46. 1.(19:36. 2-53. 1) 51.9 (3:51. 2-52.7) tarsus (mm) 13.1 (16:11.2-15.5) 19.6 (12:18.9-20.1) 22. .9 (13 :20.7-24.8) culmen (mm) 5.4(20:4.8-5.9) 8.4 (13:8.1-9.0) 9.9 (15:9.0-12.0) #1 rectrix (mm) 17.8 (7:16.5-19. 2) 26. 6 (3 :25. 9-27. 7) 107 Legend for Figure 19 Growth of Parakeet Auklets. Means of 1967 data. o o o o o o o m o in o 10 c\j CM - - (SLUDJ6) m&jaM 108 Legend for Figure 20 Growth of Crested and Least auklets. Means of 1966 and 1967 data. 109 and pusilla, respectively (table 27). The outer primary, tarsus, culmen and first rectrix also average slightly less than adult dimensions at this time (tables 21 and 27). It is not known whether these dimensions are maintained as yearlings or whether adult size is assumed soon after departure for sea. Storer (1952) determined that there was a significant difference in wing-length between yearling and older Cepphus and Uria. Brody (1945:508) has advocated use of the instantaneous growth rate in growth comparisons; the figures are usually given as a percentage gain per day. Instantaneous dialy percentage growth rates were calculated using his method for Parakeet, Crested and Least auklets and presented in averages in table 22; these instantaneous growth rates are from pooled data and the breakdown into age classes corresponds to that used by Drent (1965:144). Included in table 22 are comparative values of the instantaneous growth rates calculated by Drent (1965:144) for Cepphus columba from his study, Ptychoramphus from Thoresen (1964) and Fratercula arctica from Myrberget (1962). The rate of growth of auklet chicks during their nestling stage is treated using the definition provided by Brant (1951:346) who stated "early rate of growth in the progressive augmentation of the body as measured by the change in weight per unit of time". By comparing the slopes of the growth curves in figures 19 and 20 and from table 22 110 Legend for Table 22 Average daily instantaneous growth rates in the Parakeet, Crested and Least auklets. Data are calculated from mean body-weights of several chicks of known age. Comparative data for the Pigeon Guillemot, Cassin Auklet, and Puffin from Table 9 of Drent (1965:144), are also given. TABLE 22 Days after Parakeet Crested Least Pigeon Cass in hatching Auklet Auklet Auklet Guillemot Auklet Puffin 1-6 15.7 15.7 16.1 14.0 11.1 6.3 7-12 9.1 10.8 9.1 11.1 9.5 10.5 13-18 6.8 5.4 5.3 6.3 7.3 4.7 19-24 1.8 3.6 1.6 2.6 4.5 4.6 25-30 0.3 -0.01 -1.7 2.6 1.6 2.6 31-36 -2.5 -2.7 - 1.3 1.5 0.7 it is evident that growth in Parakeet and Crested auklets, the adults of which have similar body weights (about 300g), proceeds at a similar rate until about the seventh day when the rate of growth of the former species lags behind until about the 20th day. It is also seen that in these auklets a significant weight loss occurs immediately prior to sea-going. Parakeet chicks reach 89.4% of the average adult body weight at about 29 days of age and then lose about 10% before departing to sea; Crested chicks reach 90.8% of the average adult weight at about 27 days of age and then lose about 11% of the adult weight before sea-going; Leasts attain 98.0% of the average adult weight at about 25 days of age and then lose 10.5% of the adult weight before going to sea. Thus, the chicks of the congeners, A. cristatella and A. pusilla, show nearly identical patterns and rates of growth while growth of. Cychlorrhynchus chicks differs only slightly. The proportionately more rapid growth rate of pusilla, the adults which weigh only about 90g, may possibly be due to the size difference between it and the 300-gram cristatella (Belopolskii, 1961; Brody, 1945); smaller species have less overall body mass to initially accumulate. It is not possible at this time to provide an adequate or conclusive explanation for the pronounced pre-sea-going weight loss exhibited by these auklets, 112 however, some possibilities come to mind. In Fratercula, a starvation period of 5-11 days exists; the nestling is abandoned by its parents at about 39 days (Myrberget, 1962). This most certainly accounts for the considerable weight loss shown by this species prior to sea-going. In the present study, food was found in the neck-pouch of two Cychlorrhynchus chicks on the day immediately prior to their departure to sea and it is suspected that chicks of Aethia spp. are similarly fed. An observation on 17 August 1967 is of interest; upon visiting pus ilia nest number 10 at about 13 00 hr it was found that the chick had departed since my last visit, the previous afternoon, at an age of 30 days. An adult pusilla with food in its neck-pouch, possibly one of the parents of this chick, was in the nest; however, since neither parents was banded it is not possible to be sure it was this chick's parent. Drent (1965) found that Cepphus parents returned to their nesting ground after their young had fledged, but in the case of Aethia I have no observations to suggest this. I feel, however, that this is probably not the case in auklets for once the chicks begin to leave for sea there is a noticeable thinning out of adults in the colony. I have no data on feeding rates which might suggest a reduction in the amount of food being brought to the chicks at this time as compared to the feeding rate earlier in the chick-rearing stage. A weight loss prior to sea-going 113 was also shown in U. aalge (Johnson, 1944) and U. lomvia (Tuck, 1961) but no attempt was made by either author to account for this loss. Table 22 shows Cepphus and Ptychoramphus exhibit merely retarded growth prior to sea-going. Data for the puffin was calculated only for the period of active feeding by the parents (Drent, 1965) „ It has been noted in many species of birds that the weight of growing young increases to a peak above normal adult weight and then decreases before fledging (Ricklefs, 1968). Edson (1930) has attributed this phenomenon of weight recession to various causes (e.g., drying out of the feathers, high energy demands with rapid feather growth, starvation periods, decrease in the size of the digestive organs) but pointed out that little evidence has been sought to support any of these hypotheses. Ricklefs (1968) attributed this weight recession in nestling Barn Swallows (Hirunda rustica) to be due to the high water content of embryonic tissues, especially feathers, and the loss of water during the maturation of these tissues. Such a situation may be operative in these auklets. Many chicks, particularly pusilla, were observed exercising their wings at the entrances to their nest- sites just prior to sea-going. This increased activity at this time may result in increased energy demands resulting in a consequent drop in body weight. This raises 114 the question of the development of the feather coat which is at this time rapidly approaching completion in these species. According to Belopolskii (1961), the extra energy expended on growth and formation of transitional feathers in murres curtails the general weight increase of the fledglings. It is interesting to note that these auklets have no transitional feather coat or "mesoptile" plumage (see Grasse, 1950) but acquire their juvenal plumage directly. Kaftanowski (1951) also suggested that the energy drain imposed by the development of the mesoptile plumage reduced the general overall weight gain in Uria and Alca, however, the growth patterns in auklets differ such that the interpretations for Uria and Alca are not generally applicable. Growth of the outer primary of each auklet species is shown in figure 21. This primary begins to protrude through the skin on about the fifth day in psittacula, sixth day in cristatella and third day in pusilla. Growth is rapid and similar in each species; this primary reaches 11.1%, 84.5% and 88.8% of the adult primary lengths (table 27) in psittacula, cr istatella and pus ilia, respectively, before going to sea. Bent (1919:130) stated of pus ilia that the "wings begin to sprout when the young bird is about half grown". It is possible that he aged these chicks incorrectly as is the case in his description of plumage development in Ptychoramphus where he indicated 115 Legend for Figure 21 Growth of the outer primary in Parakeet, Crested and Least auklets. Means of 1966 and 1967 data. 70 Age (days) 116 (p. 113) that "pinfeathers begin to show at the base of the down when the chick is but 2 or 3 days old". The validity of Bent's observation is questioned by Thoresen (1964) who found primaries to protrude through the skin between the twelfth and sixteenth day after hatching. Referring to Gabrielson and Lincoln (1959) who cited the above statement of Bent, Thoresen (1964:467) accounted for the apparent discrepancy in these observations when he stated "However, 10- to 12-day-old chicks are still quite small, soft, and downy and when compared to many other species may easily be mistaken for two- to three- day-old chicks". As mentioned in Chapter III, the length of the nestling periods apparently may differ from one year to the next. This has been found by Belopolskii (1961) to exist when various points in a species' range are considered and also according to the time when the particular chicks hatch. To illustrate this, Belopolskii (1961:228) plotted the growth curves of two puffin nestlings which hatched at an interval of 15 days in northern Russia. He found a certain slowing down of the weight increase of the late-hatched chick compared to the earlier hatched one, a condition he attributed due to the fact that the growth of its feathers was faster than those of the first nestling. He found that the remiges appeared on the first nestling on the 13th day while on the second chick they 117 appeared on the 11th day. Toward the 45th day the primaries on the first nestling reached 82mm and on the 35th day they were 70mm on the second chick. The rate of development of the primaries was 2.6mm per day in the first chick and 2.9mm per day in the second. This differential pattern of growth according to time of hatching was also shown to exist in Redheads (Aythya americana) (Smart, 1965:535), where "not only did the primaries of the late-hatched group mature faster than did those of the early hatched birds, but also their tenth primaries generally matured when shorter than those of the early-hatched group". A similar disparity in growth of Least Auklet chicks in relation to their times of hatching in 1966 was found. Figure 22 presents average growth curves of Least Auklet chicks in relation to their hatching dates in 1966; the duration of these chicks' nestling period appears in table 23 (sample size in figure 22 same as in table 23). Figure 23 shows the growth curves of two pusilla chicks hatched seven days apart on St. Lawrence Island in 1966. Growth in each nestling proceeded at the same rate until about the 12th day when the growth of the first chick (#169) began to proceed at a greater rate. The abrupt increases in weight of chick #15 9 on days 10 and 20 may be explained by the presence of food in its neck-pouch at. the time of weighing. The first chick, hatched on 29 July, showed a steady weight increase until r 118 Legend for Figure 22 Growth in Least Auklets in relation to their hatching dates in 1966. Growth curve of chicks hatched between 28-31 July 1966 computed from means of five chicks; growth curve of chicks hatched between 5-6 August 1966 computed from means of three chicks. Age (days) 119 Legend for Figure 23 * Growth curves of A. pusilla chick (#169) hatched 29 July 1966 and A. pusilla chich (#159) hatched 5 August 1966. I20-. 100 - sea - going (no. 169) 80 - sea - going E (no. 159) 60 - sz 'co 40 - hatching dates : 29 July 1966 20 - 5 August 1966 0 20 25 30 35 (days) 120 Legend for Table 23 Nestling periods of Least Auklets in relation to their hatching dates, 1966, St. Lawrence Island, Alaska. TABLE 23 Periods of Hatching 28-31 July 5-6 August Hatching Date Nestling Period Hatching Date Nestling Period 28 July 31 days 5 August 29 days 29 July 3 2 days 6 August 27 days 30 July 28 days 6 August 25 days 31 July 30 days 31 July 31 days MEAN 30.4 days 27.0 days 121 about the 20th day of life; the second nestling, hatched on 5 August, increased in weight until about the 15th day. When the first nestling reached its 20th day of life, its weight had already reached its maximum; on the 32nd day of life, when it flew to sea, its weight had considerably decreased. On its 20th day of life, the second chick was much smaller but continued to grow for three or four more days, though more slowly, and flew to sea at 29 days of age and weighed less. The growth of the outer primaries in these two pus ilia chicks did not exhibit patterns completely similar to those demonstrated by Belopolskii and Smart. The primaries appeared on the first chick at 5 days of age while on the second they appeared on the 4th day; however, on the 3 2nd day when the first chick flew out to sea, its outer primary measured 53.1mm while the second chick's primary was 44.1mm when it flew out at 29 days of age. The rate of development of the primaries was 2.1mm per day in the first chick and 1.8mm per day in the second. In other words, the rate of primary growth was slower in the second chick. Considering the development of the outer primaries of five pus ilia chicks which hatched between 28 and 31 July and three chicks which hatched between 5 and 6 August 1966 the rate of development of this primary was 2.1mm and 1.8mm per day, respectively. From the limited data available it appears that pusilla chicks of later-hatchings develop 122 their plumage slightly more slowly but at an appreciable sacrifice in body weight. Due to high chick loss in 1967 these differential growth patterns were not studied. D. Thermoregulation Nestlings of birds are divided into two groups - those able to maintain more or less constant body temperatures shortly after hatching (precocial) , and those that are unable to do this, so that their body temperatures vary with the ambient temperatures (altricial). In the Alcidae (except Endomychura and Synthliboramphus whose chicks go to sea a couple of days after hatching) we find a condition where the chick is fairly well developed, alert and covered with down at hatching (precocial attributes), but remains in the nest and is fed by the parents until, in many cases, it is nearly fully grown. Although much information has been accumulated on body temperatures and thermoregulation in birds (see Baldwin and Kendeigh, 1932; Scholander, et aJL, 1950a, b and c; Smith, 1958; King and Farner, 1961; and others ) our knowledge of the ontogeny of thermoregulation is not extensive, particularly in birds which breed in an arctic environment. In this environment the development of efficient thermoregulation appears to be a critical period in the chicks' lives for cold resistence in birds is not fully developed at hatching and the chicks are often exposed to low temperatures upon hatching. 123 Previous investigations on temperature control and its ontogeny in the Alcidae have been carried out in the Russian Arctic by Kaftanowski (1951) and Rolnik (1948). These.authors placed newly hatched chicks in coolers of c. 10°C air temperature and recorded their body temperatures for several hours using thermocouples. Their observations indicate adequate development of thermoregulation at about three days in Uria aalge, three to four days in Alca torda, three to four days in Cepphus grylle and six to seven days in Fratercula arctica. They found that once thermoregulation had developed, the body temperatures of older chicks subjected to prolonged cooling (14-16 hours) remained almost unchanged as' compared to that before the beginning of the experiment. Working oh Cepphus in a temperate area, Drent (1965) found that chicks were about one day old before they could maintain stable body temperatures even at moderate ambient temperatures; their metabolic responses to environmental temperatures, however, were already homiothermous on the day of hatching. Richardson (1961) noted that temperatures of young Cerorhinca were rather variable but indicated well-established temperature control at hatching or soon after. On St. Lawrence Island, Cychlorrhynchus and Aethia show slight differences in timing of breeding and in nest-site selection, but there is much overlap in both 124 of these aspects of their breeding cycles. They are similar in the physiological characteristics that I was able to study, and I could not detect any significant differences in adaptations influencing temperature control and its development under natural conditions. Each species lays its eggs among the rocks or in a cliff crevice which have a remarkably stable temperature regime (see tables 14 and 24, figure 16). The time of hatching and of early life as nestlings on this Island coincides with the maximum summer temperatures for this arctic island (see tables 1, 3 and 4). However, since the nest-site temperatures apparently remain nearly constant throughout the nesting season, the environmental temperatures did not appear to affect the chicks directly. An attempt will be made here to elucidate the adaptations for survival by chicks during their early lives in a nest micro-environment of about ll°c. a> Body temperatures and thermoregulation in auklet chicks Tables 24 and 25 and figures 24 to 27, inclusive, reveal that within three or four days chicks of psittacula and cr istatella have sufficiently adequate thermoregulation to maintain essentially adult body temperatures or a little lower in the nest-site micro-environment of about 11°C. A. pusilla chicks are capable of maintaining steady body temperatures about five days after hatching. The 125 Legend for Table 24 Esophageal temperatures in Cychlorrhynchus psittacula, Aethia cristatella, and A. pusilla chicks in relation to age and burrow temperature. Temperatures are in °C. TABLE 24 Age Sample Brooded Mean Mean Burrow Difference (days) Size by Adult Esophageal Temperature Between Chick Temperature and Burrow Temperature Cychlorrhynchus psittacula 0 4 yes 36. 7 11. 1 25.6 1 4 yes 38.4 10. 6 27.8 2 5 yes 39.0 10.6 28.4 3 5 yes 38. 8 10. 0 28. 0 4 3 no 39. 2 11.5 27. 7 5 3 no 39.4 11.4 28. 0 Aethia cristatella 0 2 yes 37.5 10. 1 27.4 1 2 yes 38. 1 11.5 26. 6 2 2 yes 38. 3 10. 1 28. 2 3 1 yes 38. 3 11. 3 27. 0 4 1 yes 39.0 11.5 27.5 5 1 no 39. 0 11.1 27.. 9 6 1 no 39. 1 11. 6 27.5 Aethia pusilla 0 14 yes 37.0 11. 2 25. 8 1 14 yes 37.8 11. 2 26.6 2 12 yes 38. 0 11.4 26. 6 3 12 yes 38. 2 11.1 27.1 4 12 yes 38.4 11. 2 27. 2 5 9 yes 38.4 11.5 26. 9 6 8 no 38.4 11.2 27. 2 7 6 no 38.5 11. 2 27. 3 8 4 no 38. 7 11. 2 27.5 9 3 no 38. 8 11. 3 27.5 10 2 no 39. 0 11. 3 27. 7 126. Legend for Table 25 Esophageal temperatures of Cychlorrhynchus psittacula, Aethia cristatella, and A. pusilla during thermoregulation experiments. Temperatures are measured in °C. One chick was used for each experiment. TABLE 25 Esophageal Temperature Age Brooded At Start After 40 minutes in Change Shivering (days) Ambient Temperature about 10°C Cychlorrhynchus psittacula 0 yes 37.6 33.5 -4.1 yes 2 yes 39.1 36. 2 -2.9 yes 4 yes 39. 9 38. 1 -1.8 yes 6 no 38. 9 38.8 -0.1 no Aethia cristatella 0 yes 37.1 31. 6 -5.5 yes 1 yes 38. 2 37.1 -1.1 yes 3 yes 38. 3 37.4 -0.9 yes Aethia pusilla 0 yes 38.1 30.9 -7. 2 yes 1 yes 38. 2 30. 8 -7.4 yes 2 yes 39.8 35. 1 -4. 7 yes 3 yes 38. 3 37.0 -1.3 yes 4 yes 38.4 37. 1 -1.3 yes 5 yes 39. 0 38.8 -0. 2 yes 6 no 39. 3 39. 1 -0.2 yes 127 Legend for Figure 24 Body temperatures in nestling Parakeet, Crested and Least auklets after exposure to ambient temperatures about 11°C for 40 minutes. Plotted with respect to body weight. 40 -i O O O O Parakeet auklet © Crested auklet .9 © Least auklet 3 r 1 1 1 1 1 10 20 30 40 50 60 70 Body weight (grams) 128 Legend for Figure 25 Responses of Parakeet Auklet of ages 0 day to 6 days to ambient temperatures. The same chick was used throughout the experiment. August, 1967, St. Lawrence Island, Alaska. 129 Legend for Figure 26 Responses of Crested Auklet of ages 0 day to 3 days to ambient temperatures. The same chick was used throughout the experiment. August, 1967, St. Lawrence Island, Alaska. Temperature (°C) 130 Legend for Figure 27 Responses of Least Auklet of ages 0 day to 6 days to ambient temperatures. The same chick was used on each successive day. July, 1967, St. Lawrence Island, Alaska. Temperature (PC) ages at which these auklets are able to thermoregulate appear to coincide with the cessation of continuous brooding by adults, at least during the day. Bedard (1964) and Drent (1961) showed that older chicks of Alca and Cepphus, respectively, were brooded by the parents even though the ability to thermoregulate had been established. The nature of the auklet nest-sites precluded direct observations of brooding adults and the observations presented in table 25 were obtained by nest visitations throughout the chick- rearing period. Steady brooding occurred up to the time indicated in table 25 and subsequent to that brooding parents were never encountered during the daytime visitation period. It is possible that brooding of older chicks took place during the night but this was not checked. Thoresen (1964:467) found a similar situation in Ptychor amphu s where "Apparently the adults normally stay with the chick during the day until it is three or four days old at which stage the chick is able to maintain its own body temperature". Temperatures of sea-going chicks showed that adult temperatures were attained by each species. The average body temperature of four sea-going psittacula chicks was 40.1°C, of six cristatella was 40.0°C and of 11 pusilla was 40.3°C. Thus, there appears to be an early attainment.of thermoregulatory ability and a subsequent 132 attainment of adult body temperatures before the chicks depart for sea. Table 25 and figure 24 show that the body temperature of a zero-day-old psittacula chick weighing 26.3g, dropped from 37.6°C to 33.5°C within 40 minutes subjected to ambient temperatures of 11.0-11.8°C. Under equal conditions, a similar drop in temperature of a day-0 cr istatella chick weighing 28.9g was observed. In contrast, a 10.6g, day-0 pusilla chick took only about 30 minutes to reach a body temperature of 32.2°C. The small size of pusilla chicks may account for their most rapid decline in body temperature under similar conditions. A similar conclusion was drawn by Howell (195 9) who found Least Terns (Sterna albifrons) cooled more rapidly than heavier, young Kittiwakes (Rissa tridactyla) studied by Rolnik (1948) under similar conditions. Figure 24 shows the body temperatures of psittacula, cristatella and pus ilia after exposure to ambient temperatures ,c. 11°C for 40 minutes plotted with respect to body weight. There is an increase in thermoregulatory ability from hatching to approximate weights of 50g, 45g and 30g in psittacula, cristatella and pusilla, corresponding to ages of 3-4 days, 3-4 days and five days, respectively. The slower rate of development of temperature control in pusilla chicks compared to psittacula and cristatella chicks may possibly be accounted for by their smaller size; newly hatched pusilla chicks weigh 43.8 percent and 41.7 percent of the average weight of newly hatched psittacula and cristatella chicks, respectively. The surface:mass ratio of newly hatched pusilla chicks is thus greater than either psittacula or cristatella, thus facilitating greater heat loss in pusilla. The sequence of subcutaneous fat, an efficient insulator, deposition in chicks of known age was studied in 1967 and is presented in table 26. Even though sample sizes are small it may be seen that initial deposits of fat, on the abdomen and anterior part of the back, occur at about three days in psittacula and cristatella and about five days in pusilla; this corresponds closely to the onset of thermoregulation in thes*e species but it is not known the degree of importance to be attached to this relationship. In view of the apparent demands by the arctic environment on newly hatched auklets, it is useful to review some aspects of behavior and biology of chicks and adults which appear to reduce the effects of a cold but constant nest-site micro-environment and facilitate survival during the development of thermoregulation. The problem of heat conservation appears to be met by the following adaptations during the early life of auklet chicks: 134 Legend for Table 26 Subcutaneous fat deposition in chicks of C. psittacula, A. cristatella and A. pus ilia from hatching to sea-going. A scale of 5 (0-4) is used. TABLE 26 Age of chick C. psittacula A. cristatella A. pusilla in days 0 0 (2)* 0 (3) 0 (2) 3 1 (2) 1 (1) 0 (2) 5 1 (1) 1 (2) 1 (2) 14 2 (1) 2 (1) 2 (1) 24 3 (2) 3 (2) 4 (3) 28 4 (1) 4 (3) 3** (4) 33 4 (2) 4 (2) 35 3** (3) ' 3** (2) Sample size in parenthesis Sea-going age 135 (1) Chicks are covered with fine, long down at the time of hatching, and this down is retained until gradually replaced by the juvenal plumage; thus, the chicks are well insulated at all stages of growth. The length of the down on parts of the body, measured in millimeters, of one-day-old chicks of psittacula, cristatella and pusilla, respectively, were as follows: crown, 7; dorsum, 16; ventor, 8; wings, 13. Crown, 8; dorsum, 14; ventor, 8; wings, 11. Crown, 6; dorsum, 13; ventor, 7; wings, 7. (2) Auklets lay their eggs and raise their young in nest-sites which have a very stable micro-environmental temperature. (3) The chick is continually brooded by the parents after hatching for about three days in psittacula, about four days in cristatella and about five days in pus ilia; this period of brooding coincides with the age at which these species' are capable of maintaining constant body temperatures. It is not known to what extent if any older chicks are brooded and night brooding takes place. (4) Young, semi-precocial auklet chicks remain in the nest-site and are fed by the parents; consequently more energy can be used for more rapid growth and for more rapid development of efficient thermoregulation. This point is discussed by Koskimies and Lahti (1964). (5) Shivering, an important means of extra heat production in birds (West, 1965), occurred in each species 136 soon after exposure to temperatures c. 11 C during their early life. (6) Subcutaneous fat, an efficient insulator, was deposited within the first few days of life in chicks of each species. (7) The rate of cooling of a hot body depends on its surface area and modifications in the effective area are achieved by alterations in posture (Davson, 1964). The typical posture of a newly hatched auklet chick is a huddled position usually in a corner of the nest crevice. ' (8) The development of the feather coat, initially composed largely of blood-quills which increase the surface area through which blood is flowing and consequently the area through which heat may be lost, develops after essentially adequate thermoregulation sets in. E- Fledging of Chicks Parakeet, Crested and Least auklet chicks depart for sea, on the average, at 35, 34 and 29 days of age, respectively, when they are fully feathered in the juvenal plumage and with homiothermy comparable to that of the adults. Table 27 reveals the slightly smaller sizes of the chicks at sea-going compared to adults. Despite the fact that chicks are smaller at sea-going than adults, their wing areas relative to their body weights are high, 137 Legend for Table 27 Summary of relative chick body-weights and measurements to adult body-weights and measurements in C_. psittacula, A. cristatella, and A. pusilla. TABLE 27 _C. psittacula A. cristatella A. pusilla we ight 79. 3% 79. 6% 87.5% outer primary- 77. 7% 84.5% 88. 8% tarsus 91. 8% 89. 9% 85.5% culmen 93.6% 84. 1% 84.8% #1 rectrix 76.4% 79.8% 76. 9% 138 in fact, in cristatella they are higher than that of the adults (table 28). An explanation for the fact that wing loading in adults versus chicks is smaller in cristatella and larger in the other two species is not obvious. The larger wing area of adult psittacula may possibly be accounted for by its apparent more extensive migrations, however, information in this regard is scanty. The feeding methods and patterns of pursuit of prey may also be important here when considering wing loading. Sea-going by auklet chicks, which takes place primarily at night and early morning, was observed on numerous occasions in 1967. Many chicks were also observed exercising their wings at the entrances of their nest-sites during daylight hours. Several cristatella and pusilla chicks flew out singly to sea at mid-day but none was observed leaving at dusk as is common in Uria spp. (Tuck, 1961) and C. grylle (Winn, 1950). Bedard (1967) presumed that most auklet chicks left for sea during the night and early morning and Drent (1965) felt that _C. columba chicks also departed at this time. According to Lockley (1953), puffin chicks also leave their burrows at night and go to sea as do chicks of Syn th1ibor amphu s (Drent and Guiguet, 1961) . Upon becoming air-borne, auklet chicks fly directly to sea at right angles to the slope depending upon the 139 Legend for Table 28 Body-weights and wing area ratios of auklets (method of calculation follows Poole, 1938). TABLE 28 Species Mean Body Wing Area Wing Area Weight in (cm2) Per 9"ram (g) c. psittacula (adults) 280. 6 (17) * 415. 4 1. 480 c. psittacula (sea-going chicks) 222. 6(6) 249. 7 1. 121 A. cristatella (adults) 286. 6 (192) 254. 8 o. 889 A. cristatella (sea-going chicks) 228. 2(15) 229. 2 1. 004 A. pusilla (adults) 92. 0(125) 132. 9 1. 444 A. pusilla (sea-going chicks) 80. 5 (25) 96. 4 1. 197 * Body-weight sample size in parenthesis 140 direction of the wind. Their flight appeared to be fairly strong and direct with landing on the water occurring about one-half km from shore, a few instances within 100m from shore. The adults are not directly involved with the flying out of the chicks and it appears that the chicks are completely independent once at sea. Winn (1950) and Thoresen and Booth (1958) stated that juvenile Cepphus are coaxed out of the nest by the parents which dangle fish in front of them. According to Bedard (1964) Alca chicks, which leave for sea at dusk, are coaxed by one parent to leave the nest-site and flutter to sea. On 21 August 1967 a pusilla chick, 28 days of age, was released at 0400 hr from about 100m elevation on the nesting slope. It flew directly toward the water and alighted about one km from shore where it began to swim out to sea and dive within 10 minutes after alighting. On 24 August a young psittacula was observed flying out to sea at 0300 hr during a moderate wind. It remained air-borne for about three minutes before dropping down to nearly water-level then alighted. On 2 September two young cr istatella were observed about 200m from shore at 1330 hr; many dives of 25 to 35 seconds duration were undertaken. No adults were seen on the water with these chicks. Inclement weather adversely affected the survival of many sea-going chicks during both seasons. During high winds which prevailed intermittently during the sea-going periods in each year, many chicks were blown "off course" when attempting to fly out to sea. Several pusilla chicks were found dead from one-half to three km back on the tundra on top of Sevuokuk Mountain; they had been blown there by strong wind. On 1 September 1966 at 1130 hr I observed one pusilla chick attempting to fly out from the top of the Mountain. Soon after it became air-borne it was caught by wind and swept back on to the tundra about one km away. It is doubtful that many of these chicks would survive for jaegers commonly patrol this area at this time. On 1 September 1967 a cristatella chick was found running on the gravel near Gambell, probably blown there during its descent to sea from the west slope of the Mountain. On six occasions in 1966 single pusilla chicks were found dead on the nesting slope huddled against a rock with feet drawn under them. The severe chilling force of the wind had evidentally caused their deaths. As also pointed out by Bedard (1967), many fledglings which go to sea on stormy days seem unable to escape the strong tide rips and currents that prevail at the base of Sevuokuk Mountain and many were found dying on near-by beaches. The impact of such mortality is impossible to assess because larids remove the carcasses before the observer has a chance to obtain a quantitative sample 142 (Bedard, 1967; this study) and the inaccessible nature of the nest-sites precluded determining the number of chicks initially produced in the colony. On 13 September 1966 wind-blown snow fell on the nesting slope, however, it was light, did not fill auklet nesting crevices and was apparently not harmful to auklets. Table 29 summarizes sea-going dates of Parakeet, Crested and Least auklets in nests studied in 1966 and 1967. 143 Legend for Table 29 Sea-going dates of C. psittacula, A. cr istatella, and A., pusilla on St. Lawrence Island, Alaska, in 1966 and 1967 TABLE 29 1966 1967 Date of Date of Number Sea-going Number Sea-going C. psittacula 11 September .2 29 August 1 31 August 2 1 September 1 2 September 2 3 September 1 4 September 1 7 September Number of cases 10 Mean September 2.1 A. cristatella 1 5 September 5 September 1 7 September 1 September 3 8 September 2 September 1 9 September .1 September 1 10 September 1 September 1 11 September 1 12 September 1 13 September 1 14 September Number of cases 11 I'O Mean September 9.8 September 3.0 A. pusilla 3 28 August 1 15 August 6 30 August '2 17 August 4 31 August 1 18 August 1 1 September 4 19 August 1 2 September 1 21 August 1 3 September .1 23 August 1 7 September 1 25 August 2 26 August Number of cases 17 13 Mean September 1.1 August 20.5 144 CHAPTER IV. Predation As pointed out by Bedard (1967), predation upon auklets was low on St. Lawrence Island. The reason for this is not obvious for qualitative observations made at various other alcid colonies show that they are generally plagued by a host of predators (Larson, 1960; Salomonsen, 1951; Tuck, 1961; and others). Austin (1932) stated that the main requisite today for a successful colony of puffins is that it should be inaccessible to man and predatory animals. The nocturnal breeding habits pf many low arctic and boreal Pacific alcids (e.g., Synth1iboramphus, Endomychura, Ptychor amphu s, Cerorhinca) probably developed to curtail aerial predation (Bedard (1967). This cannot hold entirely true on St. Lawrence Island and other arctic alcid colonies for a 24-hour photoperiod prevails during the greater portion of the breeding season. Aerial predators were few, however, in the Sevuokuk colony. Peregrine Falcons (Falco peregrinus), deemed important aerial predators on alcids (Gabrielson and Lincoln, 1959; Murie, 1959), are represented in this Island's avifauna by only two isolated records (Bailey, 1956; Sealy, Fay and Bedard, manuscript in preparation). Its congener, the Gyrfalcon, is also relatively uncommon on St. Lawrence Island (Fay and Cade, 195 9). In 1966 I observed four 145 Gyrfalcons in the vicinity of the Sevuofouk colony; one seen on 17 June pursuing an adult A. cristatella was lost before the outcome of the chase could be ascertained. Rough-legged Hawks (Buteo lagopus) whicln were not observed during the study have been recorded taking Cychlorrhynchus and Aethia. (Fay and Cade, 1959). It is difficult to account for the paucity of these opportunistic predators on St. Lawrence Island. Bedard (1967) feels th\at fog, a prevalent climatic feature in summer on this Island, may be responsible through reducing the predators' hunting efficiency. This cannot be the overall factor for fog is an integral part of the climate of the Aleutian Islands (Murie, 1959) where, according to Gabrielson and Lincoln (1959:285), predation by the Peale' s Falcon (F. p_. pealei) is "severe" in nearly every Aleutian colony. Cade (I960) also failed to offer an explanation concerning the absence of breeding falcons on the north Bering Sea islands despite numerous potential nesting cliffs and abundant food. Jaeger predation was apparently negligible in both summers. On 8 June 1966 a Pomarine Jaeger was flushed from a freshly killed A. pus ilia but it is not known whether the jaeger killed tha aaklet or was merely scavenging. Long-tailed Jaegers were observed hunting in the colony on numerous occasions; however, upon analysis of five stomachs it was found that microtine rodents were being 146 taken. Fay and Cade (1959) examined 10 Long-tailed Jaeger stomachs taken in August (the auklet chick-rearing period), 1956 and 1957; seven contained Microtus, two contained insects and one had eaten a fish. Snowy Owls (Nyetea scandiaca) were observed five times between 29 June and 2 September 1967 near the Sevuokuk colony but not in it. Ravens nested in the colony for the last four years (from the beginning of Bedard's study to the end of the present study) but apparently assumed the role of a scavenger rather than a predator. Glaucous-winged Gulls and Kittiwakes were observed often in the colony; the former probably takes some auklet eggs and young but the latter is primarily a plankton-feeder (Tuck, 1961). Herring Gulls, which nest on the south side of the Island (Fay and Cade, 1959), elicit massive panic flights by their mere appearance (Bedard, 1967; this study), especially among A. pusilla. Three adult Herring Gulls were collected in the Sevuokuk colony in August, 1967, and their stomachs were examined. Each of two of the stomachs contained one partially digested pusilla chick and the other was empty. Predation by Glaucous Gulls was not observed in this colony. Arctic foxes (Alopex lagopus) and sledge dogs (Canis familiaris) were active in the Sevuokuk colony but their impact on the population was not ascertained. Three sledge dogs (escapees from Gambell) lived the summer 147 of 1967 in the Sevuokuk colony, particularly on the west slope of the Mountain, and on numerous occasions were seen hunting among the boulders presumably for auklets. Auklet remains (predominantly cristatella) were often found near dog tracks and feces. The nature of the nesting habits of Aethia spp. and some talus slope-nesting Cychlorrhynchus render them vulnerable to fox predation and indeed this animal is an important predator in other alcid colonies on St. Lawrence Island, which are relatively free of human molestation, for example, the Kongkok colony (Bedard, 1967; Fay and Cade, 1959). Cliff-nesting Cychlorrhynchus are relatively free from terrestial predators. Although the tundra shrew, arctic ground squirrel, red-backed vole and tundra vole live in juxtaposition to the nesting auklets on Sevuokuk Mountain, no direct evidence that shrews or ground squirrels preyed on these birds was obtained. The meat-eating tendencies of the ground squirrel on St. Lawrence Island have been documented by Geist (1933) and Cade (1951). Both authors reported this species feeding on other ground squirrels as well as other mammals; however, they were not observed eating birds. Referring to shrews, ground squirrels and tundra voles, Fay and Cade (1959:81) state that "Since each of these mammals lives in juxtaposition to nesting birds, we suspect that some eggs and young may be eaten by them". 148 Bedard (1967) did not observe ground squirrels nor red- backed voles interacting directly with auklets but held them responsible for a large proportion of deaths among embryos and chicks; the latter were often found mutilated in a way that indicated rodent predation. Seven ground squirrels stomachs, examined by me in 1966, contained plant material, predominantly Saxifraga and Sedum, which grew between the rock "stripes" on the talus slope. Murid rodent predation on sea-birds has been documented by Hague (1862), Howland (1955) and Kepler (1967). Kepler (1967) described predation by Polynesian rats (Rattus exulans) on Laysan Albatrosses (Diomedea immutabilis) on Kure Atoll, the westernmost atoll in the Hawaiian Leeward Islands. He found many dying and dead adult albatrosses with large gaping wounds in their backs which he later attributed to rat predation. A similar situation existed on St. Lawrence Island involving the three auklet species and Clethrionomys and Microtus. Several auklets of sea-going age were found with open wounds on their backs, the work of voles. These wounds were always on the dorsum of the birds, usually just anterior to the uropygial glands but in one instance, a cr istatella chick, the wound extended from the nape to the posterior border of the scapulae. Close examination of the wounds showed that only the skin was removed, the holes never being deep enough to expose the thoracic 149 cavity, ribs or lungs as was often the case with albatrosses (Kepler, 1967). In 1966 several pusilla chicks of sea• going age were found dead on the nesting slope; examination showed wounds like those described above. It was thought that the wounds were inflicted after the chicks had died due to other causes but subsequent observations of live chicks with wounds showed this to be not entirely true. While studying growth of auklet chicks in 1967 two psittacula chicks were found with these characteristic wounds; one was inflicted on 29 August when it was 31 days old and the other on 1 Spetember when it was 29 days of age (figure 28). When auklet chicks were distrubed by me they characteristically nestled into a corner of the nest-, site leaving only their dorsal surfaces exposed. I feel that a similar posture would be elicited when a vole entered an active nest-site, thus enabling the rodent to chew on the auklet's dorsal surface. On 13 June 1967 an adult A. cristatella was netted by Eskimos and left on the ground near a tent amid the auklet nesting colony. On 14 June at 0300 hr I observed a red-backed vole feeding on the auklet. It fed for about 15 minutes before leaving. On 19 June I witnessed an encounter between a Microtus and an adult A. pusilla which resulted in the vole biting the auklet's shoulder and severing a muscle which rendered the auklet flightless. The bird, an adult male, weighed 93.2g and showed extensive 150 Legend for Figure 28 Parakeet Auklet chick, 29 days old, 1 September 1967. Note wound on its back. Legend for Figure 29 Least Auklet chick, 28 days old, 31 August 1967. Note mutilated condition of the left eye. 151 subcutaneous hemmhorage on the back near the base of the neck. On 24 June I flushed a Clethr ionomys from an adult A. pusilla carcass which had been nearly completely cleaned of its musculature and viscera. The cause of death of the auklet was not known. No direct encounters between the voles and adult _C. psittacula and A. cristatella were observed. Several eggs of each species, predominantly cristatella and pusilla/ were found with large holes apparently chewed by rodents; on 18 July 1967 a Clethr ionomys was observed feeding on a live embryo in a pipped pusilla egg. Many chicks, predominantly Leasts, were found dead shortly after they had hatched with tooth marks on their flanks and partly eaten, usually their head and brain but often their wings were chewed. One pusilla chick whose left eye was destroyed by a vole or voles when the chick was two days old, lived until it was 28 days old (figure 29). Utilization of birds by St. Lawrence Island Eskimos has been discussed by Fay and Cade (1959) and Hughes (1960). 152 CHAPTER V. Molt of Adults and Juveniles The molt of Cychlorrhynchus and Aethia spp. on St. Lawrence Island was studied by Bedard (1967; unpublished data). It will suffice here to summarize briefly the basic molt patterns of the breeders showing their relations to the breeding cycles. Upon arrival at the breeding ground in May, Cychlorrhynchus and most Aethia have completed their prenuptial molt. The postnuptial molt of breeding Cychlorrhynchus and Aethia is characterized by a gradual loss and replacement of primaries a few at a time, from the inner primaries outward, rather than the simultaneous loss and replacement that occurs in the larger flying alcids, for example, Ur ia spp. (Tuck, 1961) and anatids (Kortwright, 1942) . Both genera.of auklets retain the outer primaries while molting the inner ones. The wing molt of Aethia spp. started about mid-July in 1966 and 1967 followed by body molt beginning in mid-August. The molt of non-breeders, not studied here, is briefly discussed by Bedard (1967). Figures 30, 31 and 32 show the 1966 and 1967 schedules of breeding and molt in Parakeet, Crested and Least auklets on St. Lawrence Island. It is interesting to note that the molt pattern of C. psittacula differs from that of Aethia spp. in that its prenuptial 153 Legend for Figure 30 A generalized summary of breeding activities and molt in Parakeet Auklets on St. Lawrence Island in 1966 and 1967. June July August September ^ estimated 154 Legend for Figure 31 A generalized summary of breeding activities and molt in Crested Auklets on St. Lawrence Island in 1966 and 1967. molt arrival of adults on slope post - breeding departure of adults growth of young 1966 I egg-laying hatching sea-going of A*,,, chicks •m. I Aethia cristatella molt arrival of adults on slope post-breeding departure of adults growth of young 1967 I egg-laying hatching sea-going of chicks June July August September 155 Legend for Figure 3 2 A generalized summary of breeding activities and molt in Least Auklets on St. Lawrence Island in 1966 and 1967. molt arrival of adults on slope post-breeding departure of adults /A growth of young 1966 Ilk egg-laying hatching sea-going of chicks Aethia pusilla - molt arrival of adults on slope post-breeding departure of adults | I growth of young 1967 egg-laying hatching of chicks Ilk. June July August September 156 molt occurs prior to arrival on the nesting slope and its postnuptial molt commences in early September after their chicks are reared. There is thus, partial overlap between breeding and molt in Aethia spp. but almost none in Cychlorrhynchus. As a'result of the postnatal molt, young auklets acquire their first feather covering, the Juvenal plumage. Although these species are completely covered with feathers (primaries are about 90% of the adult length at fledging) when they leave the nest, feather growth probably continues after fledging but it is not known for how long. The last traces of postnatal molt remain on the dorsal portion of the dorsal tract, the axilar region, the post-ventral region and the cervical region. CHAPTER VI. Timing of the Breeding Cycles in North Bering Sea Auklets From the foregoing examination of events in the annual cycles of Cychlorrhynchus psittacula, Aethia cristatella and A. pusilla in the north Bering Sea, it is evident that (1) from the sparse data available, C. psittacula appears to have a more extensive migration than Aethia (2) arrival of adults of both genera back on the breeding grounds in spring occurs approximately mid-May each year, (3) the pre-egg stage is prolonged but the post-breeding dispersal of adults and young from the nesting slope is rapid, (4) breeding does not take place at the same time each year, (5) Cychlorrhynchus breeds a few days later than Aethia spp., (6) a remarkable change in diet accompanies the onset of the chick-rearing period in Aethia spp. but not in Cychlorrhynchus, (7) patterns and rates of growth of chicks differ apparently according to time of hatching, (8) the chicks appear to be well-adapted to early life, (9) predation is low in the Sevuokuk colony, and (10) molt of adults overlaps the breeding effort in Aethia spp. but not in Cychlorrhynchus. Ecological and behavioral specializations in the annual cycles of these auklets reveal certain adaptive 158 adjustments to the arctic environment, particularly to the short summer. Depending upon the phenology of the particular year, summer on St. Lawrence Island lasts from about the middle of June to early September. From a cursory examination of the breeding biology of these species it appears that they are faced with two problems in timing their cycles. Breeding must take place within a period which is largely dictated by climate and they must make best use of the food supply as it normally occurs in that period. In the discussion that follows I shall look at the ultimate and proximate factors which appear to be important in timing of auklets' breeding cycles on St. Lawrence Island. A. Ultimate Factors a. Nesting Sites The availability of nesting sites is directly influenced by air temperatures in spring. Auklets arrive back in the waters proximal to their breeding grounds about the middle of May and return to the snow-covered nesting slopes a few days later. It is obvious that breeding and nesting cannot proceed when snow still covers the nest-sties. Meanwhile the auklets pair rapidly, within about a week or so after their return to the nesting slope. In 1966 and 1967 snow melt from the slope and the consequent availability nest-sites differed; 1967 159 was an early spring while the 1966 spring was late. Correspondingly, the duration of the pre-egg stage was longer (about 30 days) in 1966 and shorter (about 20 days) in 1967. However, in both years the first eggs (pusilla) were found about 10 days after the snow disappeared and nest crevices became available. What then "triggers" the reproductive processes to function at precisely the proper time in a season which may be later or earlier than the previous year? Gonadal maturation, mating and egg-laying prior to snow melt is obviously disadvantageous to the population, which was the case in 1967 where many auklets faithful to portions of the talus slope on the rim of the Mountain laid their eggs on the snow. The remainder of the breeding population was already laying eggs and incubating on the snow-free reaches lower on the slope. Barry (1962) demonstrated the effects of late seasons on Branta where fewer young are produced in some seasons than in others. Brant, which arrive on their breeding grounds on the same date each year, must also wait for the snow to melt and uncover nesting sites. If the snow persists, follicular atresia results and no eggs will be laid if snow melt is exceptionally retarded. Follicular atresia was not observed in "snow- sitting" auklets despite adequate sampling; instead the eggs were produced and laid on the snow. Food, covered by snow and consequently unavailable to Brant, was considered 160 to be one possible cause of atresia in late seasons (Barry, 1962); however, auklets feed at sea and thus can apparently obtain the necessary energy to produce and maintain mature ova. Lack (1933) found that Arctic Terns (Sterna macrura) in northern Norway laid their eggs at different dates in different areas as they successively became available after snow-melt. He suggested that the delayed availability of nest-sites and the failure of gonads to remain in breeding condition may combine to make reproduction impossible in a particular year. This situation is also in contrast to that shown by the auklets which appear unable to halt their reproductive effort. Considering Cychlorrhynchus we see that its breeding cycle is a few days later than those of Aethia spp. (figures 30, 31 and 32) even though Parakeets are the first to return in spring (table 5) . The reason for this is not obvious for, as will be seen later, there is no apparent adjustment to a food source during chick-rearing. The distribution of nesting Parakeets at least in the -Sevuokuk colony where this species largely utilizes the talus slope for nesting may shed some light on this problem. Splintered parent rock, which is located primarily along the rim of the Mountain, provides Parakeets with nesting sites. It is also along the rim that the greatest accumulation of snow occurs (figures 33 and 34) and 161 Cj Legend for Figure 33 Northeast slope of Sevuokuk Mountain showing accumulation of snow on brow of the Mountain, 5 June 1967. Legend for Figure 34 Close-up view of brow of northeast slope of Sevuokuk Mountain showing accumulation of snow, 5 June 1967. Talus slope covered by these snow drifts was utilized for nesting by several pairs of Parakeet Auklets. 162 remains latest in spring (figure 6). By breeding later Cych1orrhyn chu s is able to utilize these potential nest-sites that were unavailable to them a week or so earlier when Aethia spp. commenced egg-laying; in 196 7 only Aethia eggs were found on the snow even though several Parakeets were faithful, in some instances, to the same snow-covered habitat at the rim. b. Food and its availability The ultimate importance of food in regulating breeding seasons has been discussed by Lack (1954; 1966) and has been examined for many bird populations, mostly passerines at temperate and lower latitudes (Lack, 1954; Dunnet, 1955; Snow, 1962, 1964; and others). Lack's hypothesis has been supported by Pitelka (1959) and Holmes (1966) who worked on arctic breeding shorebirds. The remarkable change in diet that accompanies the start of the chick-rearing period in Aethia spp. prompted Bedard (1967) to point out that their nestling period has been possibly adjusted to the period of maximum available energy in the form of food. Indeed, as summarized from Bedard in Chapter III this shift from a pblyphagous diet of zooplankters to a monophagous diet (figures 17 and 18) does not appear to be fortuitous. The possibility that this shift in diet reflects a behavioral change in the adults was considered but weakly supported 163 by Bedard. From the few data available on abundance of . prey throughout the summer in surrounding waters, he feels that this sharp reversal to monophagy by Aethia apparently reflects a sudden increase in the availability of these prey items in these waters. . When considering that timing of a species' breeding cycle has been adjusted so that it can benefit from an increase in the food supply implies that lability in timing of the breeding season is possible. Holmes (1966) demonstrated that availability of snow-free tundra did not appear to regulate the onset of breeding in Red-backed Sandpipers (Erolia alpina) near Barrow, Alaska, but instead, the seasonal peak in food supply (largely Dipterous insects) seemed important. Bedard (1967) pointed out that a similar situation exists in auklets who spend as much as five weeks on the breeding grounds before laying. He stated (p. 64-66) that "In particularly good springs (1964), the nest-sites are free from snow and ice two to three weeks earlier than the actual laying date. The birds in fact seem to breed at the latest possible time in the study area". Observations on egg-laying in relation to snow-melt in this study do not bear this out entirely. It was found that the eggs were laid soon after the snow melted; about 10 days after snow-melt in 1966 and 1967 despite differences in their phenology. I have no data on year to year abundance or timing of plankton "blooms" 164 in this area which might suggest that an early spring on a landmass might be accompanied by a correspondingly early "spring" in the surrounding waters. The situation regarding Cychlorrhynchus is different; it does not appear to benefit directly from the increase, in August, of Calanus and/or of Thysanoessa (Bedard, 1967), unless as Bedard pointed out, it may benefit indirectly from the increase since the increase in plankton biomass at that time probably means an increase in the same waters of predatory organisms which Parakeets predominantly feed. When considering breeding cycles of birds, it is equally important to examine their termination as well as onset and the factors which determine these. We have seen that auklets cannot lay their eggs until the nesting crevices are free of snow in June but why do they not extend their breeding until October? Table 2 shows that snowfall does not normally occur in appreciable amounts until October; in fact, usually toward the end of October (L. Kulukhon, personal communication) and sea-ice does not form in the surrounding waters until late November (Fay and Cade, 1959) . Thus, nesting habitat is available for about four months but is utilized for only about two and one-half months. The abrupt exodus of auklets from the nesting slope is no doubt due at least in part to the food supply. Bedard (1967) found that prey items 165 utilized by Aethia were abundant during chick-rearing but disappeared quickly from the accessible layers (at least Calanus) in early September. Why Cychlorrhynchus terminates its breeding cycle shortly after Aethia is not apparent because it does not rely, on prey species which oscillate in abundance. However, since they feed on a higher trophic level, Parakeets take more carnivorous prey which may disappear when their prey disappears in September. According to Shuntov (1965), food items in oceans are affected by climate and the hydrological regime. Vinogradov (in Shuntov, 1965) stated that the main bulk of zooplankton in winter in the Bering Sea descends below the boundary of the winter-convection (200m) and its biomass in the surface layer decreases greatly. Thus, Aethia which feed on marine invertebrates obtained not far below the surface of the water would be unable to utilize prey now which was accessible to them earlier. Breeding activity of Ptychoramphus aleutica on the Farallone Islands, California, spans the period March to October (Payne, 1965; Thoresen, 1964); in other words, over a period of about eight months. This is no doubt due to the extended period of prey abundance in the southern waters of its breeding range; Payne's study (1965) weakly supports this assumption. 166 Before it can be shown with certainty that the breeding cycles of Cychlorrhynchus and Aethia spp. on St. Lawrence Island have been adjusted to the seasonal abundance of food, it is necessary to adequately sample and census the prey biomass throughout many breeding seasons and preferably in localities throughout their breeding ranges. At present it can only be said that the cyclic abundance of food organisms may influence the coarse seasonal adjustment of breeding in the species (Bedard, personal correspondence; this study). B. Proximate Factors a. Temperature during the pre-egg stage Many authors claim that an increase in air temperatures stimulates egg-laying, but this is proven for few birds in nature. I feel that no one would deny the importance of air temperature and its rise in spring on arctic breeding sea-birds. Firstly, low temperatures in winter cause the ocean to freeze over which renders food inaccessible to auklets, at least around St. Lawrence Island. Upon the onset of warmer weather in spring the ice melts; food is now accessible to them. Secondly, the presence and persistence of snow-cover on the nesting slopes, which covers nest-sites, is governed by air temperatures; early seasons like 1967 result from an earlier onset of spring temperatures, etc. Indeed, air temperatures 167 in spring are of indirect importance in initiating breeding by auklets on St. Lawrence Island for it causes snow to melt and thus provides access to nesting sites. b. Nest-sites The apparent importance of nesting sites as an ultimate factor in a bird species' breeding is obvious and discussed previously. It appears also that nesting sites act as proximate factors, factors in the changing environment to which an organism responds and which act as timers of the breeding season in the physiological sense (Snow and Snow, 1964). The absence of an "environmental stimulus" (Marshall, 1954) probably retards auklets1 reproductive processes when they find their nesting grounds covered with snow on arrival. As the snow melts, nest-sites become available to "trigger" the birds, which in many instances laid their eggs within two or three days after the snow melted (see Chapter I). c. Day-length and internal factors According to Miller (1960), full reproductive capacity of arctic breeding birds must be reached somewhat in advance of actual need in order to insure readiness and adjustment to year to year variables in weather and melting snow cover. The proximate stimulus of this recrudescence in males must be chiefly some aspect of photoperiod, either early or mid-way in the stages. Miller 168 also pointed out that this fundamental contention, originally developed and in part tested by Rowan (1929), must stand generally valid for high latitude populations. Appendix I shows sunrise and sunset times for Nome, Alaska (about one degree north latitude of St. Lawrence Island ); these data are sufficiently comparable to the photoperiod which prevails on St. Lawrence Island. It is seen that auklets breed with increasing daylight but laboratory studies have not been done to measure the effects of photoperiod on their gonad recrudescence. 1. The testis cycle in adult male auklets Figures 35 and 36 show the testis cycle in adult male A. pusilla in 1966 and 1967, respectively, on St. Lawrence Island. It is seen that gonads of males are somewhat advanced upon arrival as compared to those of resting size in late summer (August and September). It is interesting to note that the average weight of left testes in A. pusilla may differ from year to year at the time of arrival on the nesting grounds; on 27 May of both years, this weight was 0.121g in 1966 and 0.176g in 1967. In A. cristatella this weight was 0.445g in 1964, an early year (Bedard, personal correspondence), and 0.167g in 1966, a late year. It appears that gonads develop independently of conditions on the nesting ground at that time but the birds apparently are able 169 Legend for Figure 35 Seasonal change in testis size (weight of left testis) of Least Auklets in 1966. Weights include only adult males. 170 Legend for Figure 36 Seasonal changes in testis size (weights of left testis) of "snow-sitting" and "rock-sitting" Least Auklets in 1967. Weights include only adult males. Left testis weight (centigrams) o — ro OJ J>cn o> b — ro '01 cn ai ~>i 4——i Ji——i il 1 _J 1 i t i i II OJ ~ O 171 to "predict" an oncoming early season and arrive with more advanced gonads in such a year. They are thus capable of acting physiologically to earlier appearing nest-sites. Testis weights in adult "snow-sitting" versus "rock-sitting" A. pusilla males are shown in figure 36. It was felt that those birds courting and searching for nests under the rocks would be in a more advanced stage of gonad development on a certain date in the pre-egg stage than those courting on the snow and presumably unaffected by visual stimuli provided by the nest-sites. This is supported by data in figure 36 but the sample size is inadequate and further discussion is not warranted. Histolgic examination of testes of these groups would possibly reveal real differences if any exist.. C. Additional Adaptations for Timing in Auklets (1) The sense of location exhibited by these auklets enables them to establish themselves on the snow-covered slope when they return in spring and thus curtail time involved searching for nests when the snow melts. Nest-site tenacity would apparently reduce intra- specific competition for nest-sites, and the segregation on the nesting slopes demonstrated by Bedard (1967) reduces interspecific competition for nests. This is in contrast to Brant and other arctic breeding geese which, as nesting habitat becomes available, compete violently for nest-sites (Barry, 1962). (2) Patterson (1965) suggested that both colonial nesting and synchronization of egg-laying have an anti- predator function. Kruuk (1964) felt that since the total number of predators is probably limited by the amount of available food during the rest of the year and by intra-specific aggression, concentration of Black-headed Gull nests into the shortest possible time will reduce the total losses over the season. In the present study, predation was found to be low and it appears unlikely that auklets' timing is influenced by this factor. (3) The ability shown by these species to maintain nearly adult body temperatures within the first few days of life enables both parents to feed the chick during the apparent increasing food supply at this time, at least in the case of Aethia. (4) It appears that these auklets have shortened the stages of their breeding cycles in adapting to the arctic environment. The incubation and nestling periods of Parakeets, Cresteds and Leasts are about 35 days in the former two species and about 30 days in the last. Considering the temperate breeding auklet, Ptychor amphu s aleutica, we find that it has an incubation period of "at least 37 days" and a nestling period of about six weeks (Thoresen, 1964). It is of interest to examine 173 nestling periods in these species, particularly A. pus ilia where the sample size is larger, in 1966 and 1967 (table 17) and according to the time of hatching in 1966 (table 23) . From data available it appears that Crested and Least chicks generally remained in their nests longer in 1967. This appears to have resulted from slower growth of chicks in 1967. (5) The differential pattern of growth shown by earliest hatched chicks in 1966 compared to those hatched late in the same year reveals certain possible adaptations to a late season. Figures 22 and 23 show these growth patterns. Chicks hatched early grew faster and assumed a greater body weight, possibly through a greater deposition of subcutaneous fat, and departed for sea weighing more, and about three days older, than late-hatched chicks. This differential growth pattern in A. pusilla resulted in a simultaneous departure time (about 30 August 1966); thus, those chicks hatched late may also exploit the apparently increased food supply at this time. I have no information on post-fledging mortality in these species which might reveal differences in survival between these two groups. According to Perrins (1966) , those Slender- billed Shearwaters (Puffinus puffinus) which fledge early survive better than those which fledge later. Harris (1966), however, found no correlation between any phase or rate of chick development and the laying date in the same species. As Harris pointed out, a possible critical factor influencing the production of young which will survive to join the breeding population is not the availability of food during the breeding season but the success of the young in finding food after leaving the colonies. He said that if there was plenty of food available when the first chicks leave they could learn to feed economically, whereas, later chicks might perish when food became short because they had less opportunity to learn. (6) Breeding and molt of most temperate land-birds are incongruent with respect to their onset and duration. Both appear to be timed to the seasonal abundance of food. Lack (1954) proposed that the separation of these events of the annual cycle suggests that both breeding and molt are accompanied by increased energy drains on the birds. Similar controls are thought by many observers to regulate the timing of cycles of sea-birds, many of which breed and molt at different times of the year (Ashmole, 1962, 1963; Bent, 1919; Dorward, 1963; Maher, 1962; Salomonsen, 1944; and others). Compromises between the separate schedules, however, have been reached in others; some tropical and arctic breeding sea-birds have overlapping schedules (Dorward and Ashmole, 1963; Johnston, 1961; Maher, 1962). Payne (1965) documented overlapping of these schedules in the Cassin Auklet in a temperate latitude 175 As shown earlier, there is a partial overlap between breeding and molt in Aethia spp. but almost none in Cychlorrhynchus. Looking at the feeding relationships of these species throughout the breeding season may shed some light on the differential timing of these events in their annual cycles. (Bedard, 1967:84-85) felt that these molt patterns may possibly be related to differences in feeding habits and states "It seems advantageous for Aethia spp. to undertake molt during the chick-rearing period for, both species can obtain during the latter part of the breeding season preferred foods in apparently super-abundance. On the contrary, Cychlorrhynchus, whose mainstay is not known to oscillate so much in availability, has the opportunity of spreading more evenly its necessary energy expenditure and as noted in Chapter I, does not start molting until the very end of the chick-rearing period". This explanation appears feasible with our present knowledge for it is thought that parental care of eggs and young raises the food requirements of adult birds during the breeding season (Payne, 1965) and breeding adults must obtain enough extra food for the growth of the young as well as for their own increased activity. This appears to be what is happening with Aethia and Cychlorrhynchus. D. Summary of Timing The arguments outlined in this chapter indicate that the proximate factors affecting the onset and course of the breeding season are of primary importance in dictating the annual cycles of Cychlorrhynchus and Aethia. The timing observed in these species on St. Lawrence Island, Alaska, is seen to be a series of adaptive compromises related to the short season available for breeding and to the cycle of change in the food supply. 177 SUMMARY 1. Cychlorrhynchus has a more extensive migration than Aethia. 2. Arrival of adults of Parakeet, Crested, and Least auklets occurs about mid-May each year on St. Lawrence Island. 3. The pre-egg stage of Parakeet, Crested, and Least auklets on St. Lawrence Island (extending from the time the birds first come ashore at the colony until the first egg is laid) was about one month in 1966 and about three weeks in 1967. 4. At the time of arrival of adult auklets on the colony in spring the nesting slopes are covered with varying amounts of snow. Adults of the three species of auklets settle in a non-random fashion on the snow above their future nest-sites. 5. As shown by banding, Crested and Least auklet pairs remain intact for more than one year. 6. Re-use of the nest-site of previous seasons appears to be the rule in established pairs. 7. Copulation occurs at sea and on the nest-site. 8. Nest-sites in these auklets are described; four main types are utilized by Parakeets, three main types by Crested, and five main types are utilized by Leasts on 178 St. Lawrence Island. Nest-sites are naturally formed crevices among the boulders on the talus slope. No nesting material is used. 9. Onset and peak of egg-laying in Aethia spp. were studied in 1966 and 1967 and in Cychlorrhynchus in 1967. Extreme earliest dates for clutch commencement were 14 June and 4 July in A. cr istatella, 12 June and 4 July in A. pusilla and 21 June in C. psittacula. Egg-laying in relation to snow-melt is discussed. 10. Each species lays one egg to a clutch. 11. In 1967, an early year, one irrefutable case of renesting in Cychlorrhynchus and two possible instances of renesting in each of A. cristatella and A. pusilla were recorded. 12. Statistics on the period from laying to hatching are presented. The "incubation period" of C. psittacula was about 35 days, of A. cristatella was about 35 days and of A. pusilla was about 31 days. 13. Incubation temperatures in these auklets were measured with the aid of thermocouples; "spot" measurements- were taken of adult birds1 brood patches within 15 seconds after capture by hand on their nests. Temperatures in the nest-sites were relatively constant, varying within a few degrees around 11°C. ) 17S 14. Brood patch temperatures averaged 36.9 c ii C. psittacula, 38.1°C in A. cristatella and 38.0°C in A. pusilla. 15. Both sexes of each species incubate. 16. Nestling periods in these auklets averaged 35 days in C. psittacula, 33 days in A. cristatella and 29 days in A. pusilla. 17. Growth in body weight and certain body parts (culmen, rectrix, outer primary, tarsus) from hatching to nest departure were studied in each species. At the time of sea-going the juveniles averaged about 80 percent of the adults' body weight in C. psittacula and A. cristatella and about 85 percent in A. pusilla. 18. Patterns and rates of growth of A. pusilla chicks and possibly chicks of the other two species differ according to time of hatching. The nestling period is shorter in late-hatched chicks compared to the nestling period of early-hatched chicks. 19. The chicks of each species are well-adapted to early life. Thermoregulation of essentially adult body temperatures sets in at about three days of age in C. psittacula and A. cristatella and at about five days of age in A. pusilla. 20. Nest departure was witnessed several times in 1967. 180 The greater proportion of chicks departed for sea during the early morning hours. 21. Predation was low in the Sevuokuk colony; microtine rodents were mainly responsible. 22. Molt of adults overlaps the breeding effort in Aethia spp. but not in Cy ch1orrhyn chu s. 23. The importance of the ultimate factors, nesting sites and food for the young, in timing of these species' breeding cycles on this Island are stressed. 24. The importance of temperature, nesting sites and photoperiod as proximate influences on initiation of breeding are discussed. 25. Additional adaptation for timing in these auklets were discussed; these were, (1) nest-site tenacity, (2) early onset of thermoregulation which allows both parents to feed the chick, (3) shortened breeding events compared to temperate breeding alcids, (4) differential pattern of growth of A. pusilla chicks according to time of hatching which allows all chicks to depart simultaneously, and (5) overlapping of breeding and molt in Aethia spp. but not in Cychlorrhynchu s. 26. The timing observed in Aethia spp. and Cychlorrhynchus on St. Lawrence Island is seen to be a series of adaptive compromises related to the short season available for breeding and to the cycle of change in the food supply. 182 REFERENCES American Ornithologists' Union. 1957. Check-list of North American birds. Fifth edition. Lord Baltimore Press, Baltimore. Armstrong, E.A. 1954. The behavior of birds in continuous daylight. Ibis, 96:1-30. Aschoff, J. 1955. Jahresperiodik der Fortpflanzung beim Warmbluttern. 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Low reproductive rates in birds, especially sea-birds. Proc. XI Int. Ornith. Congr., 540-547. 1962. Animal dispersion in relation to social behavior. Oliver and Boyd, Edinburgh. 193 Legend for Appendix I Sunrise and sunset times at Nome, Alaska. Bering Standard Time. Data from the Nautical Almanac Office, United States Naval Observatory (1959). JAN. FEB. MAR. APR. MAY JUNE JULY AUG.. SEPT. OCT. NOV. DEC. DAY Rise Set Rise Set Rise Set Rise Set Rise Set Rise Set Rise Set Rise Set. Rise Set Rise Set Rise Set Rise Set A.M. P.M. A.M. P.M. A.M. P.M. A.M. P.M. A.M. P.M. A.M. P.M. A.M. P.M. A.M. P.M. A.M. P.M. A.M. P.M. A.M. P.M. A.M. P.M. 1 9 59 2 12 8 45 3 47 7 11 5 19 5 19 6 54 3 32 8 28 1 50 10 11 1 30 10 39 3 04 9 09 4 42 7 19 6 11 5 31 7 47 3 43 9 25 2 16 2 9 58 2 14 8 42 3 50 7 07 5 22 5 16 6 57 3 28 8 32 1-48 10 14 1 33 10 37 3 08 9 06 4 45 7 15 6 14 5 27 7 50 3 39 9 28 2 14 3 9 57 2 16 8 39 3 54 7 04 5 25 5 12 7 00 3 25 8 35 1 45 10 17 1 35 10 35 3 11 9 02 4 48 7 12 6 17 5 23 7 54 3 36 9 30 2 12 4 9 56 2 18 8 36 3 57 7 00 5 28 5 09 7 03 3 21 8 38 1 42 10 20 1 37 10 33 3 14 8 59 4 51 7 08 6 19 5 20 7 57 3 33 9 33 2 11 5 .9 54 2 21 8 32 4 00 6 56 5 32 5 05 7 06 3 18 8 42 1 40 10 22 1 40 10 31 3 17 8 55 4 54 7 04 6 22 5 16 8 00 3 30 9 36 2 09 6 9 52 2 23 8 29 4 04 6 53 5 35 5 01 7 09 3 14 8 45 1 38 10 25 1 42 10 29 3 21 8 52 4 57 7 01 6 25 5 13 8 04 3 26 9 38 2 07 7 9 51 2 26 8 26 4 07 6 49 5 38 4 58 7 12 3 11 8 48 1 35 10 28 1 45 10 26 3 24 8 48 5 00 6 57 6 28 5 09 8 07 3 23 9 41 2 05 8 9 49 2 29 8 23 4 11 6 46 5 41 4 54 7 15 3 07 8 52 1 33 10 30 1 47 10 24 3 27 8 45 5 03 6 54 6 31 5 06 8 10 3 20 9 43 2 04 9 9 47 2 32 8 19 4 14 6 42 5 44 4 50 7 18 3 04 8 55 1 31 10 32 1 50 10 21 3 31 8 41 5 06 6 50 6 34 5 02 8 14 3 17 9 45 2 03 10 9 45 2 35 8 16 4 17 6 39 5 47 4 47 7 21 3 00 8 58 1 29 10 35 1 53 10 18 3 34 8 38 5 09 6 46 6 38 4 59 8 17 3 14 9 48 2 01 11 9 43 2 37 8 13 4 21 6 35 5 50 4 43 7 24 2 57 9 02 1 27 10 37 1 56 10 16 3 37 8 34 5 12 6 43 6 41 4 55 8 20 3 10 9 50 2 00 12 9 40 2 40 8 09 4 24 6 31 5 53 4 40 7 27 2 53 9 05 1 26 10 39 , 1 59 10 13 3 40 8 31 5 15 6 39 6 44 4 51 8 24 3 07 9 52 1 59 13 9 38 2 43 8 06 4 27 6 28 5 56 4 36 7 31 2 50 9 09 1 24 10 40 2 02 10 10 3 43 8 27 5 18 6 36 6 47 4 48 8 27 3 04 9 53 1 58 14 9 36 2 47 8 03 4 31 6 24 5 59 4 32 7 34 2 47 9 12 1 23 10 42 2 05 10 07 3 47 8 24 5 21 6 32 6 50 4 44 8 30 3 01 9 55 1 58 15 9 33 2 50 7 59 4 34 6 21 6 02 4 29 7 37 2 43 9 15 1 22 10 43 2 08 10 04 3 50 8 20 5 24 6 28 6 53 4 41 8 34 2 58 9 57 1 57 16 9 31" 2 53 7 56 4 37 6 17 6 05 4 25 7 40 2 40 9 19 1 21 10 45 2 12 10 01 3 53 8 17 5 27 6 25 6 56 4 37 8 37 2 55 9 58 1 57 17 9 28 2 56 7 52 4 41 6 14 6 08 4. 22 7 43 2 37 9 22 1 20 10 46 2 15 9 58 3 56 8 13 5 30 6 21 6 59 4 34 8 40 2 52 9 59 1 57 18 9 26 2 59 7 49 4 44 6 10 6 11 4 18 7 46 2 33 9 26 1 20 10 47 2 18 9 55 3 59 8 09 5 32 6 17 7 02 4 30 8 44 2 49 10 00 1 56 19 9 23 3 03 7 45 4 47 6 06 6 14 4 14 7 49 2 30 9 29 1 19 10 47 2 21 9 52 4 02 8 06 5 35 6 14 7 05 4 27 8 47 2 47 10 01 1 56 20 9 21 3 06 7 42 4 50 6 03 6 17 4 11 7 53 2 27 9 32 1 19 10 48 2 24 9 49 4 06 8 02 5 38 6 10 7 08 4 23 8 50 2 44 10 02 1 57 21 9 18 3 09 7 39 4 54 5 59 6 20 4 07 7 56 2 23 9 36 1 19 10 48 2 28 9 46 4 09 7 5.9 5 41 6 07 7 12 4 20 8 54 2 41 10 03 1 57 22 9 15 3 13 7 35 4 57 5 56 6 23 4 04 7 59 2 20 9 39 1 19 10 48 2 31 9 43 4 12 7 55 5 44 6 03 7 15 4 17 8 57 2 38 10 03 1 58 23 9 12 3 16 7 32 5 00 5 52 6 26 4 00 8 02 2 17 9 42 1 20 10 48 2 34 9 39 4 15 7 51 5 47 5 59 7 18 4 13 9 00 2 36 10 04 1 58 24 9 09 3 19 7 28 5 03 5 48 6 29 3 56 8 05 2 14 9 46 1 20 10 47 2 38 9 36 4 18 7 48 5 50 5 56 7 21 4 10 9 03 2 33 10 04 1 59 25 9 06 3 23 7 25 5 06 5 45 6 32 3 53 8 09 2 11 9 49 1 21 10 47 2 41 9 33 4 21 7 44 5 53 5 52 7 24 4 06 9 06 2 30 10 04 2 00 26 9 03 3 26 7 21 5 10 5 41 6 36 3 49 8 12 2 08 9 52 1 22 10 46 2 44 9 29 4 24 7 41 5 56 5 49 7 27 4 03 9 10 2 28 10 04 2 01 27 9 00 3 30 7 18 5 13 5 37 6 39 3 46 8 15 2 05 9 55 1 24 10 45 2 48 9 26 4 27 7 37 5 59 5 45 7 31 3 59 9 13 2 26 10 03 2 03 28 8 57 3 33 7 14 5 16 5 34 6 42 3 42 8 18 2 02 9 59 1 25 10 43 2 51 9 23 4 30 7 33 6 02 5 41 7 34 3 56 9 16 2 23 10 03 2 04 29 8 54 3 36 7 13 5 18 5 30 6 45 3 39 8 22 1 59 10 02 1 27 10 42 2 54 9 19 4 33 7 30 6 05 5 38 7 37 3 53 9 19 2 21 10 02 2 06 30 8 51 3 40 5 27 6 48 3 35 8 25 1 56 10 05 1 28 10 41 2 58 9 16 4 36 7 26 6 08 5 34 7 40 3 49 9 22 2 19 10 02 2 07 31 8 48 3 43 5 23 6 51 1 53 10 08 3 01 9 13 4 39 7 23 7 44 3 46 10 01 2 09 Add.one hour for Daylight Saving Time if and when in use. I certify that the above data are the result of an accurate and true com• putation by the Nautical Almanac Office, United States Naval Observatory, •. ' an agency charged by Federal Statute (9 Stat. L 374, 37.5) with the duty of making such computations and publishing the results. E. W. WOOLARD Director Nautical Almanac U. S. Naval Observatory • C. G. CHRISTIE Captain, USN Superintendent U. S. Naval Observatory