Dietary separation in three species of shrew inhabiting water-cress beds



The diets of three species of shrew (Neomys fodiens, Sorex araneus and S. minutus) living sympatrically in an area of water-cress beds were investigated over a two-year period by faecal analysis of live-trapped animals. Thirty-eight different prey types were identified in the diet of N. fodiens, 25 in the diet of S. araneus and 18 in S. minutus. The most important prey items of N. fodiens in all months were freshwater crustaceans and cased trichopteran larvae. Other important items were terrestrial gastropods, coleopterans and dipterans. Neomys fodiens foraged underwater throughout the year and 33–67% of its prey were of aquatic origin. Major prey items of S. araneus throughout the year were lumbricids, terrestrial gastropods and coleopterans. Araneids, isopods and coleopterans were the dominant dietary items of S. minutus. All terrestrial prey items were taken in greater proportions by S. araneus and S. minutus than by N. fodiens, excepting lumbricids which were never eaten by S. minutus. Dietary overlap was greatest between S. araneus and S. minutus at 57%, followed by N. fodiens and S. araneus (44%) and least similar were N. fodiens and S. minutus (36%).