Harvest Mouse – Micromys minutus
Breeding nests are the most obvious sign indicating the presence of harvest mice. Harvest Mice are the only British mammal to build nests of living woven grass well above ground. Nests are around 10cm in diameter and tend to be found in dense vegetation such as grasses, rushes, cereals, grassy hedgerows, ditches and brambles. They are generally located on the stalk zone of grasses, at least 30cm above the ground in short grasses and up to a metre in tall reeds. Harvest mice also produce solitary or non-breeding nests, which are smaller, with a diameter of around 5cm.
Nests are built from leaves that have been split lengthways (strips roughly 1-2 mm wide) and are woven together to form the framework of the nest. These leaves are still attached to the plant, supporting the nest by keeping it attached to the surrounding vegetation (see below for some examples). In autumn, most nests will be brown in colour and the entrance hole can be visible indicating that the nest is vacant.
Harvest mice have many predators: weasels, stoats, foxes, cats, owls, hawks, crows, even pheasants.
Very small size weighing only 6g when adult. Fur is a sandy brown colour with a paler underside. Has a blunt muzzle, small eyes and small hairy ears. The prehensile (capable of grasping) tail is the same length as the head and body. Only 5-7cm long.
Hazel Dormouse (Muscardinus avellanarius)
Much larger than harvest mouse. Orange/yellow coat on top with yellow underside and white on throat, unlike golden-brown colour of harvest mouse, which also has a very pale grey/white underside. Prominent, big black eyes, whereas harvest mouse has small eyes. Medium sized ears, more prominent than those of harvest mouse. Furry tail. Harvest mouse tail is much less furry.
Like harvest mice, dormice also build nests. The main difference between the dormouse’s woven nest is that grass is detached from the stem to weave. Dormice nests are 10-15cm, are often found in trees and are made of woven bark or leaves, making them harder and less easy to compress.
House Mouse (Mus domesticus)
Much larger than harvest mouse. Grey/brown fur, unlike golden-brown of harvest mouse. Much more prominent ears than small subtle ears of harvest mouse and bigger eyes. Greasy fur, strong smell.
Wood Mouse (Apodemus sylvaticus)
Much larger than harvest mouse. Red/brown on top, darker than golden-brown of harvest mouse. Large eyes and ears, compared to small eyes and small subtle ears of harvest mouse. If you get a closer look: black fur on top of tail that is not present in harvest mouse. Wood mouse has white underside with longitudinal yellow/orange streak between forelegs.
Yellow-necked Mouse (Apodemus flavicollis)
Much larger than harvest mouse. Red/brown on top, darker than golden-brown of harvest mouse. Large, prominent eyes and ears, compared to small eyes and small subtle ears of harvest mouse. If you get a closer look: black fur on top of tail, not present in harvest mouse. Yellow-necked mouse has an unbroken yellow band across neck, joining forelegs.