200 ANNALS OF SCOTTISH NATURAL HISTORY 



Dun its habits, therefore, are nocturnal. It began to move 

 about at dusk, 10.30 to 11 o'clock, and from that time to 

 midnight most of my captures were made. The species feeds 

 largely, if not exclusively, on grass and various seeds the 

 stomachs in the case of a score or so examined being filled 

 with a greenish pulp. Of baits meal and biscuit were taken 

 freely, whereas cheese, in my limited experience, was a 

 complete failure. 



With regard to trapping it was found that the most 

 productive spots were cleits, especially when filled with hay. 

 Traps laid in the open never brought a single mouse. The 

 bait was frequently attacked by Forficnla, Oniscus, and Arion 

 ater, the last springing many traps. More serious were the 

 depredations of the gulls, who sometimes took away mice, 

 sometimes both mice and traps. 



The species is distributed fairly commonly round Village 

 Bay and in the glen. On Dun it is abundant, and the men 

 who sometimes sleep in a semi-underground house there say 

 that at night the mice run over their bodies in numbers. 

 They are agreed that no mice occur on Boreray, while as to 

 Soay no evidence was forthcoming. 



Two nests were discovered, neither of them typical. 

 The first was discovered on the lower slope of Oisaval while 

 a boulder was being examined for spiders. It had no external 

 opening nor any indication of the presence of a mouse. 

 Between the lower surface of the boulder and the hillside 

 there was a V-shaped gap, one corner of which was filled by 

 a large tuft of carex. Its leaves did not quite reach the 

 stone surface, but grass had been blended with them to fill 

 the space. This outer layer surrounded a central mass of 

 similar material bitten into short lengths and very soft. 

 When all the nest was removed a small burrow appeared 

 leading into the hill. Dimensions about 10 ins. by 4 ins. 



The second was in Dun, and situated in a turfy bank 

 about 2 feet in. The main burrow led to a Fork-tailed 

 Petrel sitting on her egg, and just before it reached this a 

 branch broke off to the left, to another, probably disused, 

 petrel nest. The whole flask-shaped ending and part of the 

 burrow itself were filled with chopped grass finer than in the 

 previous example. This mouse nest was separated by the 



