The diet of polar bears (Ursus maritimus)from Svalbard, Norway, inferred from scat analysis

Abstract

The diet of polar bears in the Svalbard area was assessed based analyses of scats (n=119) collected in the Archipelago between 2003 and 2010. Most of the samples were collected in spring. Morphological analysis of the prey remains together with genetic analyses of tissue fragments found in the scats showed that ringed seals (Pusa hispida) were the most important prey group present; this seal species occurred in 58% (CI 48.6%-67.0%) of the scats. Ringed seal pups were particularly abundant (45.4%, CI 36.2%-54.8%). Bearded seal (Erignathus barbatus) and birds seemed to be minor components in the diet, while Svalbard reindeer (Rangifer tarandus platyrhynchus), considering its size and the frequency with which it occurred in the scats (9.2 %), likely plays a more important role in the diet than previously reported. Whether reindeer are hunted actively by the polar bears or occur in the diet via scavenging is uncertain. Terrestrial plants and marine algae occurred more frequently in the polar bear diet than would be expected from accidental ingestion, with 32.8 % (CI 24.4%-42.0%) and 21.8 % (CI 14.8%-30.4%) of scats containing these food items, respectively. It appears that they are eaten deliberately; perhaps to meet nutritional requirements for mineral nutrients or vitamins. This study has shown that scat analysis is a useful method for assessing the diet of this large carnivore, despite the advanced state of digestion of food items in most polar bear scats.