Functional and comparative digestive system anatomy of Arctic ungulates

Abstract

Dietary niche, feeding type classification and seasonal strategies of Rangifer tarandus and Ovibos moschatus discussed in relation to the anatomy of their digestive system. Classification criteria for the flexible feeding type system, originally established in bovids and later adapted to cervids, are substantiated and critically discussed in the light of recent attempts to invalidate the system. Eurasian mountain reindeer, North American barren-ground caribou, Svalbard reindeer and Victoria Island caribou are seasonally adaptable, opportunistic ruminants of the intermediate feeding type but the long evolutionary sepatation of Svalbard reindeer has modified several morphological features for winter survival without lichen, resulting in better adaptation to fibrous forage. Muskoxen, despite their seasonal selectivity, are typical grass and roughage eaters with extremely long mean retention time. Detailed data on the entire digestive system from muzzle to anus on both species are still insufficient and extended studies are worthwhile for understanding their nutritional niche and feeding adaptations.