1915] The Ottawa Naturalist. 133 



The habitations consist of a number of burrows, many of 

 them running close to the surface, and often extending over 

 an area of, at least, 20 feet across. From these burrows there 

 may be several entrances or exits, as the case may be, as well as 

 numerous blind runways. One burrow somewhat deeper than 

 the rest is enlarged at its lower extremity to form a summer 

 resting place. All these burrows twist about in a most intricate 

 manner, and, as a rule, have their entrances hidden in a clump 

 of weeds or grass, well away from the piles of sand thrown out in 

 excavating. 



At the approach of winter the pocket mouse becomes still 

 more industrious. Two or more chambers are constructed at a 

 depth of about three feet and in these are stored variovis seeds 

 for winter use. Then having finished the task of providing food, 

 the burrows above the stores are tightly closed from below 

 and a much deeper hole commenced, which is doubtless intended 

 to take the mouse below the frost line. At the end of this 

 burrow, which is about six and a half feet below the surface, a 

 winter home is constructed by digging out an enlarged chamber 

 and lining it with a scanty supply of Green Foxtail heads. In 

 this home the pocket mouse passes the winter, probabh^ much 

 of it in sleep, as those kept in captivity became very sluggish 

 when exposed to even a moderately cold atmosphere. 



The method of constructing a winter home, after the mouse 

 has retired for the winter, wants confirming. As further evi- 

 dence, however, to indicate that the winter home is constructed in 

 the manner described above, I may mention an instance in 

 which I dug out a burrow in late October before the mouse 

 had retired, when no burrow occurred below the store cham- 

 bers, though just above them was the material that would after- 

 wards form the winter nest. Thus there is every reason to be- 

 lieve that the mouse gathers all that is necessary, in the form of 

 food and nest-making material before winter commences and 

 constructs the true winter home after retiring from above 

 ground for the winter. 



A remarkable fact about the two fully constructed burrows 

 dug out on November 10th, was the finding of a dead pocket 

 mouse at the entrance of the lower store chamber in each in- 

 stance, the dead animal being presumably the owner of the 

 home. Both these mice had been dead several days and each 

 had a hole eaten in its head, and the brains extracted. Both 

 these mice were males. Thinking that perhaps a female, or 

 whatever the kind of animal was that killed them, might be hiding 

 in an unobserved chamber, I made a very careful search for any 

 hidden hole, btit without avail. I am still of opinion, however, 

 that there must have been some hidden burrow that I failed to 



