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Draft

Due to their environment, caribou have developed adaptions and methods for efficiency during the warm months as well as for warmth during the cold months. The body composition of caribou varies highly with the seasons.

The environmental variations play a large part in their nutrition, as winter nutrition is crucial to adult and neonatal survival rates. Lichens are a staple during the winter months as they’re a readily available food source, which reduces the reliance on stored body reserves. Despite lichens being a crucial part in the diet of all caribou, they are less prevalent in the diet of pregnant caribou compared to non-pregnant individuals. This is in part because although lichens are high in carbohydrates, they are lacking in protein that vascular plants provide. It was shown that the amount of lichen in a diet decreased with increasing latitude. Nutritional stress is highest where lichen abundance was low. Lichen abundance is more closely related to adult survivorship than pregnancy itself.

Breeding females have more body mass than nonbreeding females between the months of March and September with a difference of about 10kg. However, in the November-December, nonbreeding females have more body mass than the breeding females. Body masses of both breeding and non-breeding females peaked in September. During the March-April reading, breeding females have more fat mass than the nonbreeding females with a difference of almost 3kg. After this however, every reading afterwards showed that the nonbreeding females had more fat mass than the breeding females.

Bibliography

Allaye Chan-McLeod AC, White RG, Russell DE. 1999. Comparative body composition strategies of breeding and nonbreeding female caribou. Canadian Journal of Zoology. 77(12): 1901-1907

Joly, K., Wasser, S. K., & Booth, R. 2015. Non-invasive assessment of the interrelationships of diet, pregnancy rate, group composition, and physiological and nutritional stress of barren-ground caribou in late winter. PLOS ONE, 10(6).

Wilmer, Pat; Stone, Graham; Johnston, Ian (2009). Environmental Physiology of Animals. Wiley. pp. 645-663. ISBN 9781405107242.