Apodemus flavicollis Melchior, 1834
Muridae

Description

A small rodent with dark brown dorsal colouration (with reddish and golden tones) that contrasts sharply with the white ventral colouration in adult individuals. Externally, it is very similar to the wood mouse (Apodemus sylvaticus), their diet and breeding patterns also coincide. It is more arboreal than the wood mouse and thus it can be found occupying nest boxes. It is a Central European forest-dwelling species, traditionally associated with mature deciduous forests. 

Likewise, it can be found very frequently occupying edible dormouse nest boxes throughout the year and it might use them for breeding, food accumulation, shelter and daytime resting.

Distribution

It is distributed throughout much of the European continent and the Far East, from the northern third of the Iberian Peninsula and southern England, to southern Scandinavia, western Russia, Syria and Iran. It is absent from the Mediterranean islands, although the wood mouse inhabits them.

Its presence in Catalonia was confirmed at the end of the 20th century, based on studies carried out in Montseny by using the enzymatic electrophoresis technique. In the north-eastern Iberian Peninsula, it seems to be mainly distributed in humid deciduous forests. The populations inhabiting the Catalan coastal mountain ranges  are the most southern of the Iberian Peninsula. 

Habitat and feeding

This is a species with Central European forest environmental requirements, traditionally associated with mature deciduous forests, although it can also be found in scrubland or other open environments with dense cover at low altitudes. 

Its diet is based on high-energy seeds (acorns, beechnuts, hazelnuts), although it also incorporates animal food (invertebrates).

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Feeding

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Breeding

Breeding pattern varies according to geographical area. It occurs between early spring and autumn in northern and Central Europe and in the high Pyrenees. In the Mediterranean region, instead, reproduction extends from autumn to the following spring, with a summer dormancy period. This pattern is very similar to the wood mouse, and this breeding period can be extended when environmental conditions are favourable (years with a good acorn crop, wet years). Population peaks are mainly limited by food availability and the density of individuals (dense-dependence). The yellow-necked mouse is a prolific polygamous species and can have three litters of 1 to 11 pups per breeding season (mean 5.7). Females are territorial, while males overlap their territories and compete for females. 

Inside the boxes, it makes a nest very similar to that of the edible dormouse, as both species fill the box with leaves. However, the yellow-necked mouse uses dry leaf litter that it collects from the forest floor, unlike the edible dormouse, which uses green leaves that it cuts from the same tree.