- The Eurasian water shrew (Neomys fodiens) is one of the most fascinating small mammals found across Europe and parts of Asia. This semi-aquatic creature belongs to the family Soricidae and represents one of the few shrew species specifically adapted for life both in and around water.
- Physically, N. fodiens is notably larger than many other shrew species, measuring 7-9.5 cm in body length, with an additional tail length of 4.5-7.7 cm. Its weight ranges from 12-18 grams. The species exhibits distinctive coloration, with dark, almost black fur on its dorsal side that contrasts sharply with the lighter, often white or silvery underparts. This countershading provides excellent camouflage both in water and on land.
- One of the most remarkable adaptations of N. fodiens is its swimming capability. The species possesses stiff hairs on its feet and tail that trap air bubbles, providing both buoyancy and insulation while swimming. These specialized hairs also form effective paddles, enabling efficient propulsion through water. The water shrew can swim both on the surface and underwater, where it hunts for prey.
- The species’ metabolic demands are exceptionally high, requiring it to consume approximately 125% of its body weight in food daily. Its diet is diverse, including aquatic invertebrates, small fish, amphibians, and terrestrial insects. Water shrews are accomplished predators, using their sensitive whiskers to detect prey movements both in water and on land. Their saliva contains a mild venom that helps immobilize prey, making them one of the few venomous mammals.
- In terms of habitat, N. fodiens prefers areas near clean, fast-flowing streams, rivers, and other water bodies with dense vegetation cover. They create burrows in banks, usually with multiple entrances, some of which may be underwater. These shrews are primarily nocturnal but can be active during daylight hours, particularly in secure habitat areas.
- The reproductive biology of water shrews involves a breeding season typically running from April to September. Females can produce 2-3 litters per year, with each litter containing 3-8 young. The gestation period is approximately 24 days, and young shrews become independent at about 6 weeks of age. Their lifespan in the wild is relatively short, usually not exceeding 18 months.
- The species’ ecological role is significant as both predator and prey. While they control populations of various aquatic invertebrates, water shrews themselves serve as food for larger predators such as owls, herons, and pike. They are also considered biological indicators of water quality and ecosystem health, as they require clean, unpolluted water bodies to thrive.
- Conservation concerns for N. fodiens primarily relate to habitat degradation, water pollution, and the channelization of waterways. While not currently considered threatened across most of its range, local populations can be significantly impacted by these environmental changes, highlighting the importance of maintaining clean, natural waterways for their survival.
