Water vole
A much-loved British mammal, widely known as “Ratty” in the children’s classic The Wind in The Willows, but don’t mistake it for a brown rat!
Is spring on its way? I asked myself as I looked out the window at the beginning of this month, wondering if St Swinthin’s Day had passed me by without me noticing and whether I should invest in a new pair of waders, as I planned my day out in the field. As is most of the country, the Hampshire Avon Valley near to GWCT HQ has been a landscape of water for some months now, and our water meadows are slowing the flow as much as they can, but the rain has hardly stopped, and water is still all around us drowning crops. As the water levels of the river have kept rising, it has made me wonder how the water voles were doing along the riverbank.
“Sudden and magnificent, the sun’s broad golden disc showed itself over the horizon facing them; and the first rays, shooting across the level water-meadows, took the animals full in the eyes and dazzled them. When they were able to look once more, the Vision had vanished, and the air was full of the carol of birds that hailed the dawn.” - Kenneth Grahame, The Wind in the Willows
The water vole (Arvicola amphibius), is a charming species, Britian’s largest semi-aquatic rodent, which has chestnut-brown fur (Scotland’s water voles often appear darker, with many having a black coat); a blunt, rounded nose, small ears, and a furry tail, which is 60% of head and body; and is much bigger than other British vole species, weighing in at 150-300g and 9.5-14cm in length from nose to tail tip. Water voles are sometimes misidentified with brown rat when swimming in the water, but the brown rat is larger, with grey-brown fur, a pointed nose, large ears that protrude from its fur, and a long, scaly tail.
Water voles live in the dense vegetation along slow flowing rivers, streams and ditches, around ponds and lakes, and in marshes, reedbeds and areas of wet moorland, hiding away in series of extensive burrow systems underground. These burrows have sleeping/nest chambers at various levels in the steepest parts of the bank and usually have underwater entrances to give the animals a secure route for escape if danger threatens. Because of this, they are quite hard to spot unless you know where to look.
How to spot them
Male voles live along about 130 metres of water bank, while females have ranges about 70 metres long, and they like to sit and eat in the same place, so look for piles of nibbled grass and stems that may be found by the water's edge, showing a distinctive 45 degree, angled-cut at the ends. They deposit distinctive, cigar-shaped faeces in latrines. These latrines occur throughout and at the edges of their range during the breeding season, which might be a key indicator that they are present in the area. Do also look for burrows in the riverbank, often with a nibbled ‘lawn’ of grass around the entrance, and listen out for the classic ‘plop’ as they drop into the water. I remember hearing that very clearly for the first time as I sat in the well-known pub garden of The Mayfly on the River Test in my late teens.
Breeding
Water vole pups are born between March and October, in three to four litters a year of up to five young. However, in cold or flooded conditions like we are experiencing now, breeding can be delayed until May or even June, making the breeding season a lot shorter, which will limit success. Although blind and hairless at birth, young water voles grow quickly, and are weaned at 14 days.
Decline and protection
Once a regular sight in ditches, streams and rivers across the UK, water vole range and numbers have significantly declined (absent from the Channel Islands, Isles of Scilly, Scottish islands, Northern Ireland and the Isle of Man). Water voles are fully legally protected in England and Wales under the Wildlife and Countryside Act 1981 (as amended), which makes it an offense to kill, injure or take them or possess them (alive or dead). It is also an offense to damage, destroy, disturb, or obstruct a structure or place used for shelter or protection. However, even with all this protection afforded to them, the water vole is still classified as Endangered in England and Wales and Near Threatened in Scotland.
Recent evidence indicates that water voles have undergone a long-term decline in Britain, disappearing from 94% of their former sites. Predation by the introduced American mink has had a severe impact on water vole populations, even causing local extinctions. Habitat degradation, habitat loss, housing developments, intensification of agriculture and pollution – both directly through contamination of water bodies with pollutants and indirectly through eutrophication, the build-up of nitrogen levels in water, which causes algal blooms and loss of their food plants – are also thought to have contributed to the decline of the water vole. Up to 70% die during the winter months because they can’t find enough food, the weather can get too cold, and flooding can destroy their homes.
What can we do?
Water voles are short lived, most living for only five months. But however short lived, they are a vital part of our river ecosystems. Their burrowing, feeding and movements help to create conditions for other animals and plants to thrive, but they have suffered huge declines and need our help. Undertaking predator exclusion and control (mink), bank side management – leaving areas uncut, reducing livestock riverbank poaching – and pollution control provide viable tools for sustaining local populations.
Do read about the GWCT’s involvement of a water vole reintroduction project, here on the Hampshire Avon, one of many reintroduction projects the GWCT has been involved in.
Megan Lock
Advisory
Image credit: David Mason