Thesis (M. Sc.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references. Also available via the World Wide Web.

Thesis (M.S.)--Oregon State University, 1987. / Typescript (photocopy). Includes bibliographical references (leaves 88-97). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Hawaii at Manoa, 2001. / Includes bibliographical references (leaves 114-133). Also available on microfiche.

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This study discusses the breeding biology of the Bufflehead (Bucephala albeola; Anatidae, Aves), and examines factors operating upon the species during the breeding season to evaluate their effectiveness in setting limits to its breeding distribution. A definition of the breeding habitat utilized by the species is offered, with special attention being paid to the form and spatial relationships of the nest-hole. Precise details on nesting are presented and compared with those of related species. Factors which may affect the survival of young under varying conditions are examined critically for correlations with observed mortality. On the basis of these data it is suggested that climate is of major importance in limiting the breeding distribution of Bufflehead. Climate limits the distribution of trees, and thus of nest-sites, while luxuriant growth of shrubs in regions of high rainfall may limit the fraction of young reaching the water. Adverse weather may cause mortality both by causing chilling and by preventing small young from feeding. It is felt that further studies on waterfowl which involve relationships between nest-sites and territories might profitably use this species as a vehicle. / Science, Faculty of / Zoology, Department of / Graduate

A theoretical model of flock size in migrating birds is developed. Although previous models of formation flight in birds show improved flight performance, they do not explain flock size variation across bird species or at different times of the year for a given bird species. This model captures some of the diversity in flock size observed in nature by incorporating energetic costs of flight and energy income from foraging. It turns out that within a myriad of possible flock sizes there - is one that is optimal for maximizing energetic efficiency (net energetic gain/energy expenditure) for a given maximum range speed, which minimizes flying cost per unit distance flown, and under certain migration conditions (i.e. flight distance and total time to complete the journey). Net energetic gain from foraging equals the rate of prey encountered times the time spent foraging. Energy expenditure from flying is determined from formation flight theory for a fixed wing aircraft. The benefit of formation flight, as derived from an approximation technique, is represented in close-form. This expression is a function of flock size and wing-tip spacing (WTS) and simplifies flight cost calculations. Under certain WTS, a good approximation to the induced drag for a member of a flock of size n is 1/nth of the induced drag of a single bird. In addition, optimum flight speed of a flock is (1/n)⅟₄ of the optimum flight speed of a single individual. The approach taken here allows the prediction of flock size in migrating birds. Model results are discussed in relation to observation of flock size under various migration conditions. If migration is constrained by hours of daylight, seasional variation in flock size is expected if the start time of the north and southward migration are asymmetrical with respect to the summer solstice (June 21). Under certain conditions, such as long non-stop migration, solo flight is an optimum migratory strategy. / Science, Faculty of / Zoology, Department of / Graduate

This study examined several aspects of the neural control of locomotion in birds. Initially, it was necessary to define an index of normal locomotor functions. This was accomplished for both flying and walking using electromyographic analysis of forelimb and hindlimb musculature to determine which muscles best define the flight and walking patterns respectively. Secondly, in chronic surviving birds, a series of subtotal spinal lesioning experiments were performed to determine which descending pathways were responsible for the initiation of hindlimb locomotion. Thirdly, results were recorded from brainstem electrical stimulation studies designed to determine the location of locomotor areas in the avian brainstem which effected the initiation and descending control of locomotion in these animals. Results indicated the iliotibialis cranialis (ITC) and flexor cruris lateralis (FCL) muscles best define the swing and stance phases of hindlimb locomotion, respectively. Muscles which best defined the elevator and depressor phases of flying were deltoideus major (DM) and pectoralis (Pect), respectively. Results of the low thoracic selective lesioning experiments support the hypothesis that the medullary reticulospinal pathway is necessary to the initiation and control of volitional hindlimb locomotion. Further, descending input to spinal cord pattern generators via the vestibulospinal pathways may play some adjunctive role or be necessary for the descending control of locomotion. Electrical stimulation of the brainstem in acute decerebrate birds elicited locomotor behaviours in both hindlimbs and forelimbs. Four areas, including; an area near the lateral /medial spiriform nucleus; nucleus et tractus descendens trigemini; and central nucleus of the medulla, pars ventralis and dorsalis; and the lateral reticular nucleus produced varying locomotor behaviours when stimulated. Acute dorsal cord transection did not affect the electrically stimulated behaviour, indicating that descending pathways from supraspinal centres which travel in the dorsal cord do not affect the descending control of locomotion. A strong parallel exists between the results of this study in two avian species and those found in the mammalian literature. / Science, Faculty of / Zoology, Department of / Graduate

The mistletoe species Tapinanthus leendertziae, T. natalitius and Viscum combreticola and their avian dispersal agents were studied in the field during February 1977 - May 1978. The study was carried out in seven different plant communities. Year-round surveys were made of the reproductive phenology of the mistletoes. Aspects of pollination and germination of mistletoes were investigated. The birds visiting mistletoe plants were studied with respect to the rate at which they removed fruit and the way they dealt with mistletoe seeds. The diet of the Yellowfronted Tinker Barbet Pogoniulus chrysoconus, the main dispersor of the seeds of the mistletoes, was studied. Comparisons are made between mistletoes and their dispersal agents in savanna and forest biomes in South Africa, and the dispersal of mistletoes by birds in other continents of the world is· reviewed.

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No description available.