THE ORKNEY GRASS MOUSE 



465 



Nests of dry grass and roots, having a greatest diameter of 

 from 5 to 8 inches, are placed in rounded chambers in the 

 centres of small mounds. They are never at the end of a run, 

 but are approached by a network of paths suggestive of a mole's 

 "fortress." 



The mice may be seen in their runs all day, but that does 

 not imply that they are not also active in the night.^ They 

 swim well, and Mr Millais states that if pursued they will plunge 

 into a pool rather than go round by land ; one which he released 

 in a pond dived under the surface. 





t^it 



5t,|e.r ^U U U" 



^ IncVies 



Fig. 74 Plan of Nests of Orkney Vole. (The dotted line represents 



the base of the mound.) 



They do not seem to be very prolific nor to have a long 

 sexual season, and for this reason, perhaps, no "plagues" are 

 known to have occurred in the Orkneys. Mr Millais reports 

 that the first litters appear in April, and he has seen half-grown 

 young at the end of September. But Mr Kinnear found no 

 young at the end of May, except one about a quarter grown. 



' Ogilvie-Grant caught one at 10.30 p.m. 



