Browsing by Author "Churchfield, Sara"
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Item Diets and coexistence in Neomys and Sorex shrews in Białowieża Forest, eastern Poland(2006) Churchfield, Sara; Rychlik, LeszekPrey selection, food niche overlap and resource partitioning were investigated in semi-aquatic Neomys fodiens and N. anomalus and terrestrial Sorex araneus and S. minutus coexisting in marshland in Białowieża Forest, eastern Poland. Evidence of prey selectivity was found but high levels of overlap, particularly in prey size, reflected the abundance of invertebrates in field samples. Despite similarities in diets between all four species, evidence of niche differentiation was found in terms of foraging mode and prey composition. Neomys took predominantly terrestrial prey but 20% of prey of N. fodiens was aquatic (compared with 11% in N. anomalus) with Asellus being the dominant aquatic prey. Sorex shrews were exclusively terrestrial in foraging mode. All species ate predominantly small prey (<5 mm) and these were most abundant in field samples, but small prey were most important for S. minutus. Pair-wise comparisons suggested that the most important promoter of resource partitioning was body size, indicating different foraging modes. Food niche overlap was least between species most dissimilar in size. The tiny S. minutus was predominately an epigeal forager on small Araneae, Opiliones and Coleoptera; the medium-sized S. araneus fed extensively on Lumbricidae and Coleoptera; and the large, semi-aquatic Neomys fed on different amounts of freshwater prey in addition to terrestrial prey. Our results support the prediction that microhabitat selection among these species indicates differentiation in foraging mode.Item First results on the feeding ecology of the Transcaucasian water shrew Neomys teres (Soricomorpha: Soricidae) from Armenia(2006) Churchfield, Sara; Rychlik, Leszek; Yavrouyan, Eduard; Turlejski, KrisMicroscopic examination of alimentary tracts of fourteen Neomys teres (Miller, 1908) from a mountainous region in northern Armenia produced the first data on the diet of this almost unknown species of conservation concern. Twenty-three different prey types were distinguished in summer-caught shrews, all invertebrates (14 terrestrial and 9 aquatic in origin). The dominant dietary items were Coleoptera and Diptera adults, Araneae, Opiliones and Lumbricidae plus freshwater crustaceans and Trichoptera larvae. Prey ranged from <3 to >16 mm in length but those eaten most frequently were 6-10 mm in length. Although it was captured beside streams and rivers, aquatic prey comprised only 27% of dietary composition. Despite its morphological similarity to N. fodiens, its foraging niche more closely resembles that of upland populations of N. anomalus and its reliance on aquatic habitats remains equivocal.