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General Note: |
Department: Natural Resources. |
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Dissertation Note: |
Doctor of Philosophy (Ph. D.) Utah State University 1988 |
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Summary, Etc. Note: |
Summary: Field and laboratory studies were conducted to develop a model of energy expenditure in a population of white-tailed jackrabbits (Lepus townsendii). Field work in southwestern Wyoming during 1985-87 showed that the breeding season commenced at snowmelt and ceased during late- July drought. Adult females reproduced relatively synchronously and produced a mean of three litters annually. Greatest fetal production occurred in the second litter period. Collections indicated a 1:1 sex ratio, few jackrabbits>2 years-old, and a density of 7 animals / km2 in the population. Postnatal growth was sigmoidal, culminating in heavier adult females than males. Using radio -telemetry, a circadian rhythm was detected in jackrabbit activity, with movement beginning after sunset and ending by sunrise. Observations showed that season, snow cover, weather, lunar phase, and predators influenced activity. Energetics studies established the pattern of seasonal acclimatization in the jackrabbit. Basal metabolic rate (BMR), pelage thickness, and body temperature increased but overall thermal conductance (C) and the lower critical temperature (LCT) declined from summer to winter. High winds and low air temperatures elevated metabolism interactively and their effects were most pronounced during summer. Metabolic rate dee lined with incident radiation at Ta
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Index - Genre/Form: |
Electronic Dissertations. |