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Iberian Water Shrew

Neomys anomalus
LC · Least concern Eulipotyphla Soricidae
Size
5.7-8.7 cm + tail 3.7-6.5 cm
Weight
9-18 g
Activity
Variable (day and night)
Sociability
Solitary
Lifespan
18 months in the wild
Gestation
19-21 days

Description

This water shrew is smaller than its better-known relative, with which it shares much of its riverside habitat across large areas of Europe. It is distinguished primarily by a less developed fringe of swimming hairs on the feet, a detail reflecting habits somewhat less tied to water. Like the rest of its genus, it has a slightly poisonous bite thanks to a neurotoxin produced in the salivary glands—a rarity among mammals that enables it to immobilise prey relatively large for its tiny size. Until recently, part of the populations now included under its name were considered a single widespread species, until recent studies split the Mediterranean populations into a distinct species of their own.

How to identify it

Small shrew-like mammal with dark brown fur on the back contrasting with a paler belly, though with less contrast than in the Eurasian Water Shrew. Long, mobile snout and a fringe of stiff hairs along the margin of the feet, somewhat less developed than in its larger relative. It differs from the Eurasian Water Shrew by its slightly smaller size and the less marked colour contrast between back and belly.

Signs and tracks

Tiny track, barely 1-1.5 cm, visible mainly in fine mud near water, with marks from the hair fringes on the feet. Tiny, dark droppings just a few millimetres long, with aquatic insect chitin remains visible under a magnifying glass, deposited scattered along riverbanks. Builds short burrows dug into the bank with an entrance just above or flush with the water level, very similar to its larger relative, with which it shares habitat across much of Europe.

Habitat and range

Banks of streams, ponds, wetlands and waterlogged meadows, with less strict dependence on fast-flowing water than its larger relative, from lowlands up to mid-mountain areas. Distributed across much of central, southern and eastern Europe, with Mediterranean populations now separated into a distinct species following recent genetic studies.

Diet

Carnivorous, feeding on aquatic and terrestrial invertebrates, small amphibians and tadpoles caught during short, active dives, often immobilised using the slightly poisonous bite characteristic of the genus.

Behaviour

Solitary and territorial, with activity spread across short periods throughout the day and night owing to its very high metabolic rate. A good swimmer, though somewhat less specialised than its larger relative, with which it shares habitat across much of its range without competing directly.

Conservation

Maintains generally stable populations across most of its range wherever quality wetlands persist, with no evidence of documented widespread decline.

Threats

Pollution and drainage of wetlands and waterlogged meadows, canalisation of watercourses that removes bankside vegetation, and predation by introduced species such as the American Mink in some areas.

Other accounts in Soricidae

See all species accounts for hedgehogs and shrews · Full species index

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