Yellow Necked Mouse – Apodemus flavicollis

Identification
Fur is brown on the back and white on the underside. A complete band of yellow fur across the neck area, distinguishing it from the very similar wood mouse. Large ears, protruding eyes and long tail. Head and body length 9-12cm, tail length 7-12cm.
Confusion species
Wood mouse (Apodemus sylvaticus)
Slightly smaller than the yellow-necked mouse, with proportionately slightly smaller eyes and ears. Yellow-necked mouse is usually more lively and louder than wood mouse when caught. If you get a closer look: longitudinal yellow/orange streak down the chest, unlike in yellow-necked mouse which has an unbroken yellow band around the neck, joining forelegs (this is the distinguishing feature between the two species, do not attempt to identify these two species without a close up view of this, they are usually too similar to tell apart without seeing this).
Harvest mouse (Micromys minutus)
Much smaller than the yellow-necked mouse. Golden-brown on top with pale grey/white underside, whilst yellow-necked mouse has red/brown fur on top with a contrasting pale (often white) underside. Small eyes and subtle ears (often covered by fur) whilst yellow-necked mouse has large, prominent eyes and ears.
Hazel dormouse (Muscardinus avellanarius)
Orange/yellow coat on top with yellow underside and white on throat, whereas yellow-necked mouse has red/brown fur on top and very pale (almost white) underside. Hazel dormouse has larger black eyes but yellow-necked mouse has larger, more prominent ears. Dormouse has a very furry tail which yellow-necked mouse does not have.
House mouse (Mus domesticus)
Grey/brown fur on top, as opposed to red/brown fur on top of yellow-necked mouse. Brown/pink tail, whereas yellow-necked mouse has a darker tail on top. Smaller ears than yellow-necked mouse.