Nötväckans Sitta europea födohamstring

Abstract

The behaviour and cache sites of European Nuthatches storing naturally occurring beech Fagus sylvatica and hazel Corylus avellana nuts in a South Swedish wood are described. Data are also given on the retrieval of cached nuts in winter and on recaching. On average it took a Nuthatch about 1 min to cache a beech nut. A third of all caches were below 1 m, 20% in the ground. Of those in trees, most were at heights between 5 and 15 m and less than 20% on branches thinner than 4 cm; of caches made above ground, 43% were in dead, often rotten wood. The choice of cache site was related to the kind of item to be cached: a higher proportion of hazel than beech nuts was cached in the ground. Oak was used proportionally more, and other species of tree proportionally less for caching than suggested by their abundance, perhaps because oak presented much dead wood which was extensively used for caching. More than 80% of all caches were covered with material from the immediate surroundings of the cache site. The Nuthatches removed the seed coat from a high proportion of the beech nuts before caching them; however, none of those cached in the ground and similar sites were shelled. During the coldest part of the winter, 1.1 nut per hour was retrieved in a winter following a poor mast crop vs 4.6 in a winter following a rich one. Recaching was common at all times but less so in winter.