FLUCTUATIONS OF FUR-BEARING ANIMALS 225 



The periods of maximum abundance of the blue phase 

 of the arctic fox correspond in almost every case with those 

 of the white phase, so no special reference to these is neces- 

 sary. 



Wolves. — When the fluctuations in numbers of the larger 

 predatory animals, such as the wolf, are studied it is found 

 that they do not show a very regular or marked periodicity. 

 This is no doubt accounted for by the wide range of their 

 food, the grey wolf feeding on all forms of herbivorous 

 animals, from a mouse to a moose, and the prairie wolf or 

 coyote being a very general feeder, including in its diet not 

 only larger animals such as antelope or sheep, but even in- 

 sects such as locusts, and also berries. When mice or rab- 

 bits are plentiful wolves will take their share of such abun- 

 dant food, but the fact that they can also satisfy their 

 hunger with deer, caribou, or moose prevents any marked 

 decrease in their numbers when the smaller rodents are 

 killed off. In fact, if we examine the diagrams of rabbit 

 and wolf returns of the Hudson's Bay Company (the wolf 

 returns include both grey wolf and coyote) we shall find 

 that in a number of instances the greatest number of wolves 

 were taken in years of rabbit scarcity, and when rabbits 

 were at their maximum the wolf returns were low. The 

 greater difficulty of trapping wolves during periods of rab- 

 bit abundance may have something to do with this condition 

 of affairs, but it is in striking contrast to the cases of the 

 lesser carnivorous fur-bearers, the lynx and red foxes. In 

 the early days when the buffalo roamed the prairies the 

 wolves found food in plenty, and the returns from about 

 1840 onwards until the buffalo began to decrease in num- 

 bers showed no great increase or decrease. But when the 

 buffalo was gradually exterminated the numbers of wolves 

 fell to a low level, and since 1879 we find a slight, though 

 nevertheless noticeable, periodical increase every ten years, 

 the years of maximum abundance being 1888, 1898, and 1908. 



