Sorex fodiens (Pennant, 1771), Berlin, Germany. A survey of al-lozymic variation in Europe suggests that populations may show extensive differentiation within short distances.
OTHER COMMON NAMES
English: Northern water shrew; French: Musaraigne aquatique; German: Große Wasserspitzmaus; Spanish: Musgaño patiblanco.
Head and body length 2.8-3.8 in (7.0-9.6 cm); tail 1.8-3 in (4.7-7.7 cm); weight 0.4-0.7 oz (12-20 g). This species has a keel of stiff hairs on the underside of the tail, and fringes of stiff hairs on the hands and feet that aid in swimming.
Distributed in Europe and Asia. The range includes most of Europe except Iceland, Ireland, and most of Iberia. Farther east, it ranges through western Siberia as far as the Yenisei River and Lake Baikal, and south to Tien Shan and northwestern Mongolia. In east Siberia it has apparently disjunct populations from northeastern China, North Korea, Sakhalin Island, and the Far East.
It is particularly fond of streams with densely overgrown banks that provide ample hiding places among roots and stones. Inhabits clear, fast-flowing rivers and streams, lakes with abundant riparian vegetation, and ponds, marshes, watercress beds, and boulder-strewn sea shores. Only occasionally found far from water. Up to 8,200 ft (2,500 m) in the Alps.
A semi-aquatic species that moves quickly in swimming and diving. It is a marvelous experience to watch this animal hunting in water. Typically, it dives for 3-25 seconds in the field. No special adaptations have evolved to permit long-lasting diving, because this would invariably lead to hypothermia. Active by day and night, but it has an apparent preference for darkness. It is essentially solitary outside of the breeding season. Individuals are aggressive toward one another. Exhibits a marked territorial behavior with shifting territories. Home ranges extend from 210 to 320 ft2 (20-30 m2) on land, and from 650 to 860 ft2 (60-80 m2) along brooks.
It mainly feeds on macrobenthic invertebrates (crustaceans and insect larvae) in running water. Foraging is conducted in the water and on land surface, feeding on a wide range of invertebrates, as well as frogs, newts, and small fishes. The species paralyses large prey with venomous saliva.
Probably polygamous or promiscuous. The breeding season extends from April to September, reaching a peak in May and June. Two litters are generally produced each breeding season. Litter size is 3-8 (average about 6). A life span of 14-19 months has been reported.
Not listed by the IUCN, but included in the Conservation Action Plan for the Eurasian Insectivores.
SIGNIFICANCE TO HUMANS Sometimes it does damage to fish fry. ♦
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