Finding Field Voles

Under the square of roofing felt, I found a pair of tiny, baby voles. I watched them and worried for their safety, as they stumbled blindly around. They had fur, so they must have been at least 9-10 days old, but their eyes were squeezed shut and they looked incredibly vulnerable. Not wanting to disturb them too much, I took a quick photo and gently replaced the roof of their home.

The rough grassland that they were living in suggested that they were baby field voles, as opposed to bank voles, which look very similar, but prefer more wooded habitats. I wanted to be sure though, so I searched for more clues. I followed one of the well-trodden vole runs through the grass and discovered a feeding station - a pile of neatly cut grass and plantain, nibbled at the ends to form a distinctive 45 degree angle. Next to this was a latrine of fresh, green-brown droppings. All of these signs indicated that the babies were field voles.

The next day, I was eager to see how the little voles were growing and I hurried back to the tile. I peeled back the felt very slowly and gently, but my heart dropped at the sight of one of the baby voles, lying still and lifeless on the bare ground. The other one was nowhere to be seen. Sadly, I laid the tile down again, wondering how the youngsters had died. Did they fall victim to a predator – maybe even a shrew? Or had their mother died, before they were fully weaned and able to fend for themselves? I would never know.

A field vole’s life is fraught with danger and is always short. It has many different predators, including kestrels, owls, foxes and stoats, which all kill huge numbers of voles. However, field voles breed prolifically; the young females are able to mate at 6 weeks old and between March and December, a female may have 4-5 litters, each containing 2-7 young. So, despite being apparently helpless in the face of so much adversity, it is a highly successful species and at a count of about 75 million, it is the only mammal species in Britain to outnumber humans.

Now you do it
Field voles are common and their signs are easy to find, once you know what you are looking for. Search at the base of grass tussocks, or under pieces of corrugated iron for their nests - balls of grass, very loosely woven together. You may also find their feeding stations, which are piles of grass and other plants, cut into similar sized lengths with the ends usually having an angle of 45 degrees. It used to be thought that different vole species cut vegetation at specific lengths, but there is so much overlap between the species, that this is not a reliable method of identification. A more reliable method of identification is by their latrines; field vole latrines contain oval, greenish droppings of approximately 5mm in length and 2-3mm in diameter. Bank vole droppings are blacker and water vole droppings are larger (8-12mm in length and 4-5mm diameter). See the ARKive website for more information on field voles and some fantastic videos.

If you live in Sussex, why not take part in the Sussex Mammal Group’s field vole survey? See the Sussex Biodiversity Records Centre website for more information.

Live trapping, using Longworth traps, is also a good way of getting closer to field voles, but make sure that you know what you are doing first. The Mammal Society has a Longworth trap loaning scheme and runs courses on small mammal survey techniques. If you do carry out trapping, be aware that you are likely to catch shrews and will therefore need a shrew license from the relevant Statutory body (e.g. Natural England).