Yellow-necked mouse  (Apodemus flavicollis)

The yellow-necked mouse is classified as Least Concern (LC) on the IUCN Red List (1).

Although generally larger in size, the yellow-necked mouse (Apodemus flavicollis) is very similar in appearance to the wood mouse (Apodmeus sylvaticus) and the two are often difficult to distinguish (3). Both species have brown fur with paler, white bellies (2), although the yellow-necked mouse may often be somewhat lighter in colour (3). The main difference between these mice is that, as the name suggests, the yellow-necked mouse has a collar of yellowish fur, which forms a bib on the chest (3). This collar is often fairly difficult to see, however (3).

The yellow-necked mouse has a patchy distribution and is restricted to the south and west of England (except Cornwall and Cheshire), and central and eastern Wales (4). In Europe they are found mainly in mountainous parts of southern Europe, but their range reaches further north into Scandinavia than that of the wood mouse (4).

You can view distribution information for this species at the National Biodiversity Network Gateway.

This mouse appears to be associated with ancient or mature broadleaved woodlands, and usually occurs in close proximity to arable farmland. The yellow-necked mouse may also inhabit orchards, field margins, wooded gardens, hedgerows and buildings in rural areas (4).

Yellow-necked mice are nocturnal, being active for a single period each night (4). They feed on fruit, seedlings, buds and the odd invertebrate (4), often storing food within tunnel systems (3). All mice engage in 'refection' in order to fully digest food; they eat soft faeces that have passed through their digestive system once, allowing carbohydrates to be fully digested (3).

Breeding occurs from March or April until October, although under some circumstances breeding may occur throughout the year (4). Before mating, males are known to produce a string of ultrasounds, which may serve to pacify the female (3). Gestation takes 25 or 26 days (3), and the litter, which consists of 2 to 11, but usually five young (4) is born at night in a nest (3). Nests may be made in underground tunnels, inside hollow logs, bird or dormice nesting boxes or in dense vegetation (3). Around three litters are produced each year (4), and females are able to conceive whilst still suckling the previous litter (3). The young are fully weaned after about 18 days, and usually start to breed the year following their birth, but if they were born early in the year they may breed during the year of birth (4). Dominant males may be aggressive, and have been reported to chase and even kill juveniles (3). This species does not hibernate; during winter a number of these mice may group together when sleeping for extra warmth (3).

Yellow-necked mice are adept climbers, and as a result they feed in trees and bushes and enter houses more often than wood mice (3). Predators such as weasels and owls are often avoided by means of impressive leaps to safety, or by shedding the skin of the tail if it is gripped anywhere other than its base, allowing the mouse to escape. The skin does not grow back; instead that area of the tail dies and falls off (3).

As the yellow-necked mouse is associated with ancient woodland, it is likely that it is vulnerable to habitat fragmentation. However, a high dispersal ability and good reproductive potential suggests that this mouse can colonise new areas quickly (4). The increase in conifer planting may have reduced the availability of seed producing trees (4).

Research and survey work is currently being carried out on this species by the University of Bristol's Mammal Research Unit (5). This work will hopefully shed light on the conservation status of this patchily distributed species (5).

View information on this species at the UNEP World Conservation Monitoring Centre.

There may be further information about this species available via the National Biodiversity Network Gateway.

For more on the yellow-necked mouse:

• The Mammal Society yellow-necked mouse fact sheet:
  http://www.mammal.org.uk/index.php?option=com_content&id=220