REPRODUCTIVE BEHAVIOUR of the EARED GREBE, Podiceps Caspicus Nigricollis by NANCY MAHONEY Mcallister B.A., Oberlin College, 1954
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REPRODUCTIVE BEHAVIOUR OF THE EARED GREBE, Podiceps caspicus nigricollis by NANCY MAHONEY McALLISTER B.A., Oberlin College, 1954 A THESIS SUBMITTED IN PARTIAL FULFILMENT OP THE REQUIREMENTS POR THE DEGREE OP MASTER OP ARTS in the Department of Zoology We accept this thesis as conforming to the required standard THE UNIVERSITY OP BRITISH COLUMBIA April, 1955 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 representative. It is under• stood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of The University of British Columbia, Vancouver 3, Canada. ii ABSTRACT The present study describes and analyses the elements involved in the reproductive behaviour of the Eared Grebe and the relationships between these elements. Two summers of observation and comparison with the published work on the Great Crested Grebe give some insight into these ele• ments, their evolution, and their stimuli. Threat and escape behaviour have been seen in the courtship of many birds, and the threat-escape theory of courtship in general has been derived from these cases. In the two grebes described threat plays a much less important role than the theory prescribes, and may not even be important at all. In the two patterns where the evolutionary relation• ships are clear, the elements are those of comfort preening. In the three patterns in which there is still some doubt, all the elements can be related to general non-reproductive be• haviour or to nesting patterns. When courtship tapers off, nesting behaviour takes its place. The timing of this change and of the nesting be• haviour patterns is caused by a general climatic stimulus fol• lowed by a more particular behavioural one. Nest-building and egg-laying are the results of the gradual building up of the sexual condition during courtship. Egg laying, however, takes place only in warm, dry weather. If the weather changes for the worse during laying, the birds stop and wait. The effect of this double stimulus is to put the birds on the borderline between determinate and indeterminate layers. V ACKNOWLEDGMENT Br. I. McT. Cowan deserves my greatest thanks for his valuable suggestions and enthusiastic support. My thanks are also due to Dr. M. D. P. Udvardy for his help with the literature and the manuscript, to Dr. W. S. Hoar, Dr. J. P. Bendell, M. T. Myres and Donald McAllister for reading the manuscript, and to Esther Marion and Mary Jackson for assist• ance in the field work. Financial support came for the National Research Council of Canada. Ill Table of Contents Page Introduction 1 Methods 2 Organization 4 General Behaviour Patterns 6 Plight 6 Swimming 7 Resting 7 Diving 8 Bathing and preening 9 Voice 11 Comparisons of the general behaviour .......... 11 Threat and Escape Patterns 12 Occurrence of threat and escape 13 Threat attitudes 14 Alarm 16 Escape 17 Courtship Displays 18 Advertising behaviour 19 Courtship preening 21 Head shaking 22 Penguin dance 24 Cat attitude 27 Origins of the Courtship Patterns 28 Advertising behaviour 29 Courtship preening and head shaking 29 Penguin dance 31 Cat attitude 32 Summary 33 Nesting Behaviour 34 Soliciting 37 Development of platform building 38 Nest building patterns 41 Copulation 43 Abandoned eggs -. 45 Clutch size 46 Interval between eggs 51 Incubation 52 Care and Behaviour of Young 55 Predation and Mortality 57 Outlook 58 Literature Cited 59 LIST OP TABLES AND FIGURES Page Table I Water temperatures July 13, 1956 3 Table II Estimated Breeding Birds on Westwick and Sorensen Lakes 4 Table III Courtship Patterns Compared 30 Table IV Clutch Size 48 Table V Clutch size in Experimental Nests 49 Pigure 1 Map of Sorensen Lake 60 Figure 2 Map of Westwick Lake 61 Pigure 3 Sorensen Lake from the south end looking north and showing in the foreground a Scirpus marsh 62 Pigure 4 Sorensen Lake from the east side looking west toward the mountains at the edge of the Praser River 62 Pigure 5 Westwick Lake from the east side near the north end, looking south toward the narrow part of the lake 63 Pigure 6 Westwick Lake from the middle of the east side looking south at the large part of the lake 63 Pigure 7 Duration of Behaviour Patterns 64 Pigure 8 An early courting platform of Scirpus and pond weeds 65 Pigure 9 An area of sparse reeds showing five courting platforms 65 Pigure 10 A later and more substantial courting platform of reeds and decaying algae 66 Pigure 11 An abandoned egg on a courting platform 66 Pigure 12 An abandoned egg which has been pecked by the grebes 67 Pigure 13 Drawings of behaviour attitudes ..68 Introduction The comparative behaviour of birds has been studied only in the last forty years $ and attention has been limited to the more advanced groups of birds. The general rules de• rived from these studies may, then, be more restricted in their application than was at first supposed. Studies of more primitive birds, such as this of grebes, might well add to the understanding of the evolutionary development of innate be• haviour. Special consideration is here given to the develop• ment of territorial and colonial behaviour and the theory of courtship. The reproductive behaviour of grebes is known only through scattered observations over a few days or weeks, and the greatest confusion has resulted. Many individual behav• iour patterns have been described, but their places in the species behaviour are not known. The one exception to this is the British work on the Great Crested Grebe, Podiceps cristatus, from Huxley (5) to Simmons (10). The work is carefully and exhaustively done, and I have drawn on it heavily for comparative purposes. My observations are not influenced by the British work, however; I did not read the Great Crested Grebe material until my field work was complete. This project on the Bared Grebe, Podiceps caspicus nigricollis. is the beginning of a comparative study of North American grebes. Methods The study area is near Williams Lake in the Cariboo district of British Columbia, 52.00° North latitude, 122.00° West longitude, and 1500 to 2500 feet above sea level. The Cariboo Parklands biotic area or biome as described by Munro and Cowan (9) is flat to rolling grassland broken by stands of lodgepole pine (Pinus contorta), Douglas fir (Pseudotsuga menziesii), and aspen (Populus tremuloides). Frequently the bottoms of depressions in the grassland hold shallow lakes. The lakes vary in size from a few acres to twenty square miles. The Eared Grebes choose lakes about a mile by half a mile. The two lakes intensively studied are typical of these last. The study lakes, Westwick and Sorensen, were once one but are now artificially divided by an unpaved road. The sizes and proportions of the lakes are given in Figures 1 and 2. Their general setting is shown in Figures 3 to 6. The greatest depth is twelve feet, but more than half the lake area is less than five feet deep. These highly eutrophic lakes have at least a foot of thick black mud on the bottom. The clear water is filled with numerous small invertebrates, but no fish. The concentration of invertebrates is such that food does not appear to limit the populations of any of the birds using the lakes. The bottom flora reaches, by the middle of July, to within two feet of the surface and extends over ninety percent of the bottom area. In addition dense mats of floating algae cover one fourth of the surface by the end of 1 July. Mary Jaekson (pers. com.) identifies the bottom plants as Scirpus, Ruppia, Ceratophyllum, Myrophillum, and Potamogeton. and the floating forms as principally Cladophora and Aphanizo- menon. Temperatures measured with thermocouples at noon on the thirteenth of July, 1956, are shown in Table I. Table II gives a list of the breeding waterbirds of the two lakes and the ap• proximate numbers of breeding pairs per year. I am much endebted to Mary Jackson for her estimates of breeding ducks. Table I. Water Temperatures July 13, 1956 Depth in Peet Center of Lake 60 Peet from Shore 0 22.8°C. 24.5°C. 1 22.8 24.5 2 22.5 24.0 3 22.0 4 21.8 5 21.5 Total Depth 7 feet 4 feet Westwick Lake has a colony of two hundred and ten pairs of grebes, and Sorensen a colony of forty pairs. During the early part of the season observations were made from shore with a thirty power telescope and 7x35 binoculars. Later a canoe in the reeds served as an adequate blind. During the nesting season the birds were too shy to be approached by canoe, and blinds on stilts were built in the water at the edges of the nesting sites. Nests were checked by wading, and tagged with one inch square white cardboard tags numbered with India ink. 4 Table II Estimated Breeding Birds on Westwick and Sorensen Lakes The two lakes are combined and numbers are given as lower and upper extremes. Species Latin Name Breeding Pairs /year Pintail Anas acuta 1-3 Green-winged Teal Anas crecca 5-10 Common Mallard Anas platyrhynchos 7-10 Baldpate Anas americana 10-15 Blue-winged Teal Anas discors 3-8 Cinnamon Teal Anas cyanoptera 0-1 Shoveller Anas clypeata 3-6 Canvasback Aythya valisneria 3-8 Redhead Aythya americana 3-8 Lesser Scaup Aythya affinis 15-25 Barrow's Goldeneye Bucephala islandica 15-30 Buffiehead Bucephala albeola 0-8 Ruddy Buck Oxyiira jamaioensis 15-30 Coot Pulica americana 75-100 Eared Grebe Podiceps caspicus 200-300 Pied-billed Grebe Podilymbus podiceps 0-2 Horned Grebe Colymbus auritus 0-1 Sora Rail Porzana Carolina 1-4 Organization The purpose of this section is to orient the reader.