The Life of the Water Vole

Social Organisation

Water voles live in colonies, made up of a series of adjoining territories along a riverbank. Colonies can be up to 2km long.

Territories vary in lengt from 30m to 300m, depending on the sex of the territory holder, habitat quality, population density and time of year.

Male territories will often overlap those of several females.

Behaviour

Water voles follow a 4 hour activity pattern

Underground they have a burrow system with openings both below water kevel and on the bank up to 3m from the waters edge.

Above ground they create runways through the vegetation up to 2m from the waters edge.

Water Vole Calendar

JAN-FEB
There are few obvious signs of activity, as the population density is low and the water voles spend the majority of their time below ground feeding on stored food. At this time of year they nest communally.

MARCH – APRIL
The onset of the breeding season. Nesting females space themselves apart into non-overlapping territories. Latrines are established and regularly scent marked to mark the territories.

APRIL – MAY
Peak in birth rate, after a gestation period lasting 22 days. Within a few days of a female giving birth she may be ready to mate again.

JUNE
Peak in newly weaned animals, the juveniles make their first excursions from the nest at 25 days.

JULY – SEPTEMBER
2nd and 3rd litters are produced, the juvenile males and low ranking females disperse. Dominant daughters may settle inside the mothers territory and may even displace a pregnant female following territory disputes. Nests can be found above ground often woven into bases of sedges.

SEPTEMBER
The population size is at its greatest. Females born early in the year may become sexually mature and breed, the majority will not breed until the following year.

OCTOBER-NOVEMBER
There is a reduction in numbers by dispersal. Water voles begin preparation for winter by laying down underground food stores. Sexual activity ceases and territorial disputes become less frequent.

DECEMBER
Territories are now broken down as home ranges contract. There is a low survival rate amongst juveniles, whose over-wintering weight averages 170g. Voles gather together to share nests.