226 ECONOMIC MAMMALOGY 



bers that organized campaigns were necessary to stop their depredations. Dur- 

 ing this same period 61,000 jack rabbits were killed in Grant County, and 

 94,000 in adjacent counties. During the fiscal year following 2062 coyotes 

 were taken in the same district. Jack rabbits were practically at an ebb. Since 

 that time jack rabbits and coyotes have not been troublesome except in a few 

 local spots. 26 



The fluctuation in the numbers of such prolific species as rabbits, 

 mice and some other rodents are somewhat periodic, depending upon 

 various factors, especially weather, food and disease, and probably 

 not so much as we are apt to suppose upon the presence or absence of 

 predatory mammals and birds, though these birds and mammals un- 

 doubtedly do exercise a large influence in checking the increase of 

 rodents under ordinary circumstances and aid in suppressing special 

 rodent plagues. 



The larger wolves are individually much more destructive than the 

 coyotes, or prairie wolves, but fortunately are much less abundant. 

 They are able to kill larger stock and game than the coyote can destroy. 

 One was found feeding upon a dead moose, but circumstances did not 

 indicate that it had killed the animal, 27 though they are known to 

 destroy many deer. 28 One is said to have killed 125 cattle, worth 

 $5,000, in ten months, and a famous South Dakota wolf is believed 

 to have killed $25,000 worth of cattle in seven years. 29 One Colorado 

 wolf is believed to have killed 75 horses and cattle. 30 The favorite food 

 of the Arctic white wolf is said to be musk ox and caribou. 31 Wolves 

 do not disdain small rodents. It is said that in Labrador when mice 

 are very abundant the wolves leave caribou and other game alone and 

 feed upon mice, returning to a diet of caribou and ptarmigan when 

 mice become scarce. 32 The diet of the Brazilian red wolf (Chrysocyon) 

 is chiefly fruit, but it takes many small armadillos, and one stomach 

 contained seeds of the cumbaru tree. 33 



Where wolves are abundant and winters severe they have formed 



26 Couch, Relationship of predatory mammals and birds of prey to rodent life, 

 Journ. Mammalogy, ix, 73-74, 1928. 



27 Johnson, Note on the habits of the timber wolf, Journ. Mammalogy, n, 11-15, 

 1921. See Criddle, The habits and importance of wolves, Dept. Agric., Ottawa, Bull. 

 No. 13, 1925. Seton, The lives of game animals, i, Part I, pp. 251-337, 1929. 



28 Bailey, Destruction of deer by the northern timber wolf, U. S. Biol. Surv. 

 Circular No. 58, 1907. 



129 Bailey, N. Amer. Fauna, No. 49, p. 150, 1926; U. S. Forest Service Bull. No. 

 72, 1907. Bell, U. S. Dept. Agric. Yearbook for 1920, pp. 296-297. Seton, Lives of 

 game animals, i, Part I, pp. 251-337, 1929. 



30 Warren, Mammals of Colorado, p. 244, 1910. 



81 Seton, Lives of game animals, i, Part 2, pp. 340-351, 1929. 



32 Allen, Journ. Mammalogy, in, 56-57, 1922, reviewing Cabot's Labrador. 



83 Miller, Journ. Mammalogy, xi, 13, 1930. 



