The water shrew (Neomys fodiens) is the largest of three shrews native to England. Following the decline of the water vole, there was concern that this semi-aquatic mammal species was also suffering declines. Studies so far show that water shrews are localised but are probably not endangered at the moment. Real conclusions are hard to draw as water shrews are difficult to survey.
Intensive surveys of three river catchments in Sussex (Southgate & Scott, 2006) showed that water shrews are fairly widespread, although probably not living at high densities. Water shrews were found to live in a number of unusual habitats in Sussex, including heathland and vegetated shingle, two habitats in which they had previously not been recorded.
Water shrews appeared to favour less floristically diverse sites with a high percentage of reed and litter cover, high litter height, and the presence of tussocky sedges/grasses. It is likely that reedbeds, purple moor grass and unimproved floodplain grassland habitats play an important role in providing habitat for water shrews. They may have seasonal preferences for flowing water and static water sites which appear to be driven by water temperature – lower water temperatures in flowing water sites being favoured in summer.
Sussex water shrews were associated with a high diversity and abundance of aquatic invertebrates. A number of specific prey items appeared to be important in their diets such as snails and caddis flies, including Trichoptera, Ephemeroptera, Hydrobiidae, Lymnaeidae, Physidae, Calopterigidae, Chironomidae, Coleopteran and interestingly, Hydracarina (Water mites). Seasonal associations with Sphaeridae, Corixidae and Leptoceridae were also found.
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