Ecological and nutritional aspects of caribou reproduction and growth

K.L. Gerhart, R.D. Cameron and R.G. White
Institute of Arctic Biology

Supporting Agencies: Alaska Department of Fish and Game; The U.S. Fish and Wildlife Service; The Canadian Wildlife Service; The Inuvialuit Game Council, Canada; The Northern Oil and Gas Program, (NOGAP); The Department of Biology and Wildlife, UAF; a TOTE Dissertation Year Fellowship and a National Science Foundation Graduate Research Fellowship.

Wild caribou from the Central Arctic and Porcupine Caribou Herds, as well as captive caribou and reindeer held at the Large Animal Research Station, were studied in an effort to (1) characterize body composition and growth patterns in arctic caribou, and (2) estimate body composition in live animals. Captive caribou were weighed at birth, and calves and their mothers were weighed periodically thereafter. Weights from a captive caribou were compared with those from wild caribou of similar age or reproductive status. Captive adult female caribou were heavier than their wild counterparts. Body weights of captive calves were similar to those of wild caribou, however weights of captive calves were more variable. Among wild calves males were significantly larger than females by 100 days of age. However, among captive caribou, male calves were not larger than females upon entering winter.

Body composition was estimated from body condition scores, bioelectrical impedance, and marker dilution using both tritiated water and C14 urea. Ten captive reindeer males were sacrificed to estimate predictions of body fat, water, protein and ash from each of these live techniques. Body condition scores were easily applied under field conditions, and were used to study the relation between body composition in autumn and probability of pregnancy in wild caribou (Figures 7 and 8).

 
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