Field Vole Taken at Lochwinnoch on 28th February 2010 using Nikon D40X with Nikon 300 mm zoom lens.   Field Vole. Species: Order: Family: A.K.A. Microtus agrestis. Rodentia. Cricetidae. Habitat: Nest: Food: Length: Feature: Woodland, marsh or on river banks. Nest of shredded grass about 10 cm in diameter. Omnivore. Grasses, bulbs, tree bark, insects and invertebrates. 11 cm Around 75,000,000 in Britain. They are a very important source of food for owls and other raptors. As they travel, field voles leave a trail of scent to warn off other voles. Raptors, such as Kestrels, look out for the UV light that radiates from the trails.