Food caching by a Eurasian otter

In early spring of 2007, unusual feeding behaviour was observed for the Eurasian otter (Lutra lutra) when a cache of toads (n = 18), black bullheads (n = 2) and great diving beetles (min. 58 ind.) were found in a hollow tree-trunk on the shores of an oxbow lake near the River Danube. Spraint analysis identified the primary food of otters in the area to be fish, with non-fish (buffer) prey of very low importance. As the otter consumed almost exclusively fish, and appeared to store mainly buffer food items, this may indicate that either preferred fish were less available (limited) or that non-fish items were relatively more abundant for a short period during the mild ‘cold’ winter and spring period. The otter had abandoned this particular cache. Food caching is an important dietary adaptation for many species, providing readily available food during periods when fresh food may be difficult to find.