Show simple item record Eddy, Susan Bates en_US 2009-12-02T14:47:02Z 2009-12-02T14:47:02Z 1976 en_US
dc.identifier ocm72766387 en_US
dc.description.abstract Population parameters and various aspects of the life history of the leopard frog, Rana pipiens pipiens, were studied at the University of Manitoba Field Station at Delta Marsh, Manitoba over three summers. Stomach samples contained a wide variety of animals, including tadpoles and frogs of their own species. Empty stomachs were found during cold and cloudy weather, and during migration and breeding periods. Spring migration from the lake to breeding areas in the marsh took place as soon as it was physically possible and breeding occurred immediately. Fall migration seemed to be triggered by a combination of internal and external mechanisms although the weather controlled the intensity of activity on any evening. Tadpole growth varied between sites and between years, probably because of the amount of food available. There are at least three year classes of frogs, but following the fourth summer more than one year class can form a size class - growth is fastest in the second summer, and extremely slow following the third. Females grow faster than males, but the difference is not significant. Although mortality is normally high in the tadpole stage, low water 1evels resulted in even higher mortality. This was probably because of algae toxins and lack of oxygen rather than predation. During the study there was a shift in the size structure of the population due to selective mortality on younger frogs. Unusually heavy ice and north winds following the beginning of the thaw killed younger frogs, which stayed in or near the lake in early spring. By the spring of 1974 there were very few frogs left and most of these were of the largest size class. en_US
dc.format.extent viii, 84 leaves : en_US
dc.format.extent 3690995 bytes
dc.format.mimetype application/pdf
dc.language en en_US
dc.language.iso en_US
dc.rights The reproduction of this thesis has been made available by authority of the copyright owner solely for the purpose of private study and research, and may only be reproduced and copied as permitted by copyright laws or with express written authorization from the copyright owner. en_US
dc.rights info:eu-repo/semantics/openAccess
dc.title Population ecology of the leopard frog, Rana pipiens pipiens Schreber at Delta Marsh, Manitoba en_US
dc.type info:eu-repo/semantics/masterThesis Zoology en_US Master of Science (M.Sc.) en_US

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