Feeding habits and trophic niche overlap of two sympatric mustelidae, the polecatMustela putorius and the beech martenMartes foinaErnährungsgewohnheiten und Überlappung der trophischen Nischen zweier sympatrischer Musteliden, Iltis (Mustela putorius) und Steinmarder (Martes foina)Régimes alimentaires et recouvrement des niches trophiques de deux Mustélidés sympatriques, le putois Mustela putorius et la fouine Martes foina

The diets of the polecatMustela putorius (Linnaeus, 1758) and the beech martenMartes foina (Erxleben, 1777) in Luxembourg were investigated by using faecal analysis and determination of gut contents. Data of the polecat (121 scats and 16 guts) were collected around the country where the populations of this species have been sharply declining over the past decades. 112 scats of the more common and widespread beech marten were collected in those areas where both mustehds were known to be present. Standard techniques were applied for analysing the data. In winter, small mammals, especially rodents, were the most abundant food for both species. Amphibians dominated the summer diet of the polecat whereas fruits were the most important resource for the beech marten during that season. The pattern of resource partitioning between the polecat and the beech marten is based on the common use of small mammals. The niche overlap of food items is however limited and appears only during winter. The adaptation allowing the use of alternative food sources might avoid the competition for food.