Polar bears observed climbing steep slopes to graze on scurvy grass in Svalbard

Abstract

It is well known that polar bears feed on vegetation. Here, I report novel observations of polar bears grazing on polar scurvy grass (Cochlearia groenlandica) at the foot of a large seabird colony on a cliff on Spitsbergen, Svalbard, in the summers of 2005, 2006, 2009, 2014 and 2015. Why they choose such energy-costly climbing to feed on plants is not clear. One possibility is that they may be suffering from vitamin C deficiency and are searching for this particular plant, which has a high level of this vitamin. Another, but not exclusive reason, is that vegetation containing scurvy grass is abundant enough to be efficiently grazed by such unspecialized plant-eaters as polar bears only on such relatively inaccessible, steep slopes below seabird colonies. Most of the lowland and gently sloping tundra areas in Svalbard are overgrazed by geese and reindeer, the populations of which have increased considerably as a consequence of climate amelioration. Large seabird colonies are known to attract animals from different trophic levels, but this is the first description of their attractiveness to polar bears as grazing areas.