UK Conservation Status: RED

Water voles are a charismatic resident of our waterways, see this video. For many their first encounter with water voles was in the pages of The Wind in the Willows where “Ratty”, a resident of the riverbank, had his work cut out tempering the excesses of Mr Toad.  

In real life water voles are a flagship species of a healthy water environment. They are Endangered in England, primarily as a consequence of loss and fragmentation of suitable habitat. In addition, predation by feral American mink has exacerbated the pressures on the water vole populations.

Over the past two decades considerable effort has gone into eradicating mink together with various schemes to encourage riparian owners to manage bankside vegetation to support water voles. These measures have not been sufficient to reverse the decline in water vole populations generally across the country.

Nevertheless, this rat-sized vole is widespread in Cambridgeshire, though the 2016 Cambridgeshire Mammal Atlas noted its populations are isolated. They are present in the Beck Brook catchment, which drains into Cottenham Lode and includes Histon’s Brook, and have been recorded occasionally from Long Meadow.

Water voles like well vegetated banks of ditches and slow-moving rivers; there are also stable populations in large reedbeds. They are rarely found away from water.

The largest of our voles, the water vole has dark brown fur, small hairy ears and a shortish, furry tail. Its short, chubby face sports small protuberant eyes. (Brown rats which are often larger, have a greyer fur, pointed nose and a long scaly tail. The rats’ large ears protrude from its fur.)

A soft “plop” may be the sole indication you have come across a water vole as it retreats from passers-by. But you may be lucky enough to catch a view, perhaps sitting on a favoured feeding platform . More often you may see evidence of their presence, such as their distinctive droppings or neat piles of chewed grasses and broadleaved plants, with ends neatly cut at a characteristic 45‑degree angle.

They live in burrows in the river bank, with entrances above and below water level. The holes can be between 4 and 8 cm in diameter, albeit slightly squashed flat. Typically, a burrow system will have nest chambers at different levels and can extend 3m from the water’s edge.

Water voles have an average lifespan of possibly 1.5 years, with a maximum of around 3 years in the wild. Typically, they have around three or four litters each year, with the first born in spring.

All photographs taken of water voles in Histon & Impington brooks.