BRITISH MAMMALS 



THE ST KILDA FIELD MOUSE. 



Mus sylvaticus kiriensis, Barrett- Hamilton. 

 Plate 27. ' 



This is another very large sub-species, but less brightly coloured than 

 the one last described. The largest of a number of specimens, obtained by 

 Dr. Eagle Clarke on the St. Kilda group of islands in the Autumns of 19 10 

 and 191 1, measured in length of head and body 129 millimetres, the tail 

 100 millimetres, making the total length of the animal from nose to tip of 

 tail about 9 inches. The following is from his description of this fine 

 mouse in the Scottish Naturalist (June 19 14), "The St. Kilda Field Mouse 

 is confined to the main island Hirta, and to the adjacent uninhabited isles of 

 Soay and Dun. It is most abundant where coarse grass prevails, but is to 

 be found almost everywhere — in the crofted area, in the neighbourhood of 

 the houses, on the faces of the cliffs, and on the sides and hill-tops ; finding 

 congenial retreats in the rough stone-built ' cleits ' (which are such a feature 

 in the St. Kilda landscape) and in the walls surrounding the crofts ". . . . 

 " That the underparts of hirtensis are heavily washed with yellowish brown 

 has hitherto been deemed an important characteristic of the species. This 

 is not the case, however, for in the majority of adult specimens, and many of 

 the immature ones, the throat, chest, and abdomen are white, and only 

 washed with brown along the narrow medium ventral line. As a result, the 

 demarcation between the peppery reddish-brown upper, and the pale under 

 surface is pronounced in most examples, and renders the species very similar 

 to the familiar Long-tailed Field Mouse (Apodemus sylvaticus). About 

 one-third of the adults and the majority of the younger specimens have the 

 under surface more or less strongly washed with yellowish brown." 



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