COMMON MAMMALS OF WESTERN MONTANA. 



11 



always infested with ticks when occurring in suitable country. From 

 the 341 specimens examined by Mr. W. V. King and myself in the 

 course of these investigations 841 seed and 1,234 nymphal wood 

 ticks were taken, an average of G.09 for each animal. It can readily 

 be seen, therefore, that in fever-infested localities the destruction of 

 this most important host of young wood ticks must be an important 

 supplementary part of any campaign for the control of the disease. 



HIBERNATION AND BREEDING. 



Although the habits of this ground squirrel vary considerably 

 with climate and locality, in the warmer valleys it usually emerges 

 from hibernation during the latter part of March. It begins rutting 

 about a week or 10 days later and, as the gestation period is about 

 28 days, the young (averaging about 4 to 5 in a litter) are born 

 in early May. At first they are blind, naked, and helpless. In about 

 three weeks, however, they come to the surface of the ground for the 

 first time and at once begin to eat various sorts of green food. Of 

 21 young squirrels weighed between June 6 and 12, 1911, about a 

 week after their first appearance, the lightest tipped the scales at 

 2.75 ounces and the heaviest at 8 ounces. Eleven killed on June 10 

 averaged 3.75 ounces. The lightest of 30 adults weighed between 

 .May 30 and August 15 was 11 ounces and the heaviest 26 ounces, 

 the average being 17.5 ounces. 



By about June 1 the old males have begun to recover from the strain 

 of the rutting season and by the middle of July most of them are very 

 fat. From then until they enter hibernation they remain close to 

 their burrows and do little but sun themselves and eat. The old 

 females do not begin to put on fat until about the middle of July 

 and do not become so fat as the males until just before hibernating, 

 if at all. 



In most parts of western Montana the Columbian ground squirrels 

 enter hibernation about the middle of August. In the colder parts, 

 however, where they do not emerge from hibernation until the latter 

 part of April, they remain active a full month longer; and at Almota, 

 Wash., they " hole up " in July, having put in an appearance early 

 in February. Thus it appears that the time they enter hibernation 

 is usually about four and a half or five months after they emerge in 

 the spring. 



FOOD HABITS. 



The Columbian squirrel, more than most other ground squirrels, 

 prefers tender green vegetation to ripe seeds and grains. Probably 

 as a result of these food habits its cheek pouches are small and little 

 used. Among the green foods most attractive to these squirrels are 

 dandelion heads, clover, alfalfa, timothy, lettuce, strawberries and' 

 various other berries, young carrots, bean and pea vines, and grow- 



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