Mammals Active day and night

Eurasian Water Shrew

Neomys fodiens

iNaturalist Wikipedia

The world's smallest semi-aquatic hunter, the Eurasian water shrew is a venomous marvel of the riverbank. With its velvet-black fur and specialized 'oar' feet, it is as comfortable diving for prey as it is darting through the reeds.

0 Sightings

0 Habitats

Quick Identification

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Size

6-10 cm (2.4-4 in) head-body length, 4.5-8 cm (1.8-3.1 in) tail; weight 10-20 g (0.35-0.7 oz)

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Colors

Bicolored with a charcoal-black or dark grey back and a sharply contrasting silvery-white or grey belly; occasionally white tufts around the ears.

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Key Features

Stiff hairs on the feet acting as 'oars' for swimming
Venomous saliva used to paralyze prey
Fringes of silver-white hair on the underside of the tail
Dense, water-resistant velvet fur

When You’ll See Them

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Activity pattern Active day and night

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Peak hours Active in 3-hour cycles throughout the 24-hour period; peak sightings at dawn and dusk

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Season Year-round; activity is most visible during the spring and summer breeding season

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Diet Carnivorous; hunts aquatic insect larvae, crustaceans, snails, small fish, frogs, and terrestrial earthworms.

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Habitat Edges of clean, freshwater environments like streams, rivers, ponds, and reed beds with plenty of bankside cover.

public Geographic range

Where Does the Eurasian Water Shrew Live?

The Eurasian water shrew is native to the temperate regions of Europe and Northern Asia. Its vast territory spans from the British Isles across the entirety of Central and Northern Europe, reaching through Russia and Siberia all the way to the Pacific coast and the northern islands of Japan. This species is a resilient resident of the Palearctic, thriving wherever it can find clean, oxygenated freshwater and dense vegetation for nesting.

Basemap © OpenStreetMap contributors

10 Countries

35M km² Range

Least Concern Conservation

GB United Kingdom DE Germany FR France Russia PL Poland NO Norway SE Sweden JP Japan CN China IT Italy

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iNaturalist / Verified observation data

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Behavior

The Eurasian water shrew is a high-energy, semi-aquatic predator that leads a remarkably fast-paced life. It is one of the few venomous mammals in the world; its saliva contains a toxin that can paralyze small fish, frogs, and large insects, allowing the shrew to tackle prey significantly larger than itself. Because of its incredibly high metabolism, it must feed almost constantly, alternating between short periods of frantic hunting and brief bouts of sleep throughout both day and night.

In the water, this shrew is a master of efficiency. When it dives, air trapped in its dense fur makes it appear as if it is coated in silver, though this also makes the animal highly buoyant, requiring it to swim vigorously to stay submerged. While they are primarily solitary and territorial, they are occasionally seen in small groups when foraging conditions are particularly rich, though they generally prefer to keep to their own complex tunnel systems along the water's edge.

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Camera Tips

To capture the Eurasian water shrew, camera placement is everything. You must position your camera extremely low—no more than 2 to 4 inches off the ground—ideally overlooking a flat 'shelf' on a muddy bank or a known trail through bankside reeds. These shrews use the same paths repeatedly, often following the exact line where the water meets the shore. Use a camera with a high trigger speed and a fast recovery time, as these animals move with lightning speed and can cross a camera's field of view in less than a second.

Baiting is highly recommended to slow them down for a clear shot. A small amount of fish-based wet cat food, mealworms, or even crushed water snails placed in a shallow depression will often cause them to pause. Since they are small, ensure your camera's focus is sharp at close range; if your device has a 'macro' mode or a focus adjustment, use it. Setting the camera to record short 5-10 second video clips is usually more successful than still photos, as it allows you to see their unique swimming and foraging behaviors.

Nighttime is when they are most vulnerable to detection by infrared sensors, but their small body size doesn't emit much heat. Set your PIR (Passive Infrared) sensitivity to 'High.' If your camera's IR flash is too powerful, it may 'white out' the shrew at close range; you can fix this by placing a small piece of frosted tape over part of the flash to diffuse the light. Look for their burrows—small, circular holes about the size of a golf ball in the riverbank—and position the camera nearby for the best results.

Similar Species

Species that look similar or are commonly confused with Eurasian Water Shrew.

Common Shrew

Smaller with a tri-colored coat (brown, light brown, white) and lacks the stiff swimming hairs on the feet and tail.

Mediterranean Water Shrew

Very similar but typically lacks the silver 'keel' of hairs on the underside of the tail and is found in Southern Europe.

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Frequently Asked Questions

Eurasian water shrews are active both day and night throughout the year. They follow a polyphasic activity pattern, which means they alternate between short bursts of hunting and resting roughly every three hours to maintain their high metabolism.

If you have a pond or stream, you can attract them by maintaining thick, natural vegetation along the water's edge. Providing 'feeding stations' with mealworms or fish-based food near the water can also encourage them to visit your camera site.

They are primarily carnivorous hunters. Their diet includes aquatic larvae (like dragonflies), small crustaceans, snails, and occasionally larger prey like frogs and small fish, which they paralyze using their venomous saliva.

They can be found in suburban areas provided there is a clean, permanent water source and plenty of undisturbed bankside cover. They are sensitive to water pollution, so their presence is often a sign of a healthy local ecosystem.

The Eurasian water shrew is larger and has a distinct bicolored appearance with a dark back and a white belly. Look for the fringe of stiff white hairs on the feet and the underside of the tail, which the Common Shrew lacks.

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