Brown rat – Rattus norvegicus
Description: Greyish-brown fur; prominent pointed muzzle, eyes, ears and long, almost naked, tail, about as long as the head-and-body. Much larger than any mice, but comparable with the much darker, shorter-tailed water vole in general size, though less ‘chubby’ in appearance.
Size: Head & body: 15-27cm. Tail length: 10.5-24cm.
Weight: 40g at weaning, up to 600g, but usually 200-300g.
Grey/brown fur with long naked tail about as long as the head and body. Prominent pointed muzzle and prominent ears. Much larger than any mice. Often swims with just the head above the water.
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Footprints: Brown rat footprints are small and difficult to spot. They should show five straight toes (three forwards, two outwards). Width of hind foot up to 4.5cm.
Droppings: Rat droppings are putty-like, usually with a blunt end and a pointed end. Most commonly seen in farmland and urban areas. Variable in size up to 1.7cm in length and 0.6cm wide. Blackish-brown in colour. Foul, rancid smelling.
Water vole (Arvicola amphibius)
Water vole has chestnut brown fur, compared to the rat’s grey/brown fur on top and grey underside. Muzzle of water vole is fairly blunt, compared to pointed muzzle of brown rat. Water vole’s ears are subtle and usually covered by fur, whereas brown rat has larger more prominent ears. Slightly furry tail, 60% of body length, shorter than brown rat (90% of body length).