40 ECONOMIC MAMMALOGY 



Where they occur in immense colonies over a vast area in the west- 

 ern United States, prairie-dogs do great damage to fields in the vicinity 

 of their colonies, and especially to grass lands, thus reducing the num- 

 ber of cattle and sheep the plains are capable of supporting. 16 Merriam 

 estimated one colony in Texas to cover 25,000 square miles and to 

 contain 400,000,000 prairie-dogs, with an annual loss of from 50 per 

 cent to 75 per cent of the producing capacity of the land so occupied, 

 reducing by a great many thousands the number of cattle the land 

 could support. 17 



Rabbits are more or less injurious wherever they occur about orch- 

 ards, fields and gardens. The cottontails, found all over the United 

 States, gnaw the bark of orchard trees during the northern winters 

 and in the summer raid the gardens and fields. They are kept pretty 

 well in check in most localities by natural enemies, hunters and epi- 

 demic diseases, consequently are not usually abundant enough to be 

 very destructive, and at least partly compensate for the damage done, 

 by the meat and healthful sport they provide. The hares, or jack rab- 

 bits of the western plains are larger, in many places abundant, since 

 the destruction of so many coyotes, hawks and other enemies, and are 

 locally very destructive to field crops and pasturage. In one county of 

 California the damage done by them in one year was estimated at 

 $6oo,ooo. 18 Their local abundance is well shown by the number killed 

 in annual rabbit drives held in various parts of the West. It is said 

 that 59,000 were killed in one winter in an Oregon county, 40,000 in 

 one Idaho county, 15,000 in another and 20,000 in another. 19 The Eu- 

 ropean hare, introduced into New York, is said to have done damage 

 to the extent of $100,000 in a single county in one winter. 20 Rabbits, 

 introduced into Australia, where they are not native and are exempt 

 from their natural bird and mammal enemies, increased very rapidly 



16 Payne, The prairie-dog as a range pest, Colorado Agric. Exper. Sta., Press Bull. 

 No. 16, 1903. Burnett, Office Colorado State Entomologist Circular No. 8, 1913 ; No. 

 17, 1915 ; No. 25, 1916. Bailey, N. Amer. Fauna, No. 49, 1926. Taylor and Loftfield, 

 Damage to range grasses by the Zuni prairie-dog, U. S. Dept. Agric., Bull. No. 1227, 

 1924. 



17 Merriam, The prairie-dog of the Great Plains, Yearbook U. S. Dept. Agric. for 

 1901, pp. 257-270. 



18 Palmer, The jackrabbits of the United States, U. S. Biol. Surv. Bull. No. 8, 1897. 

 Bryant, Rabbits damage crops in San Diego County, California Fish and Game, n, 

 215-218, 1916 (both jackrabbits and cottontails). 



19 Bell, Yearbook U. S. Dept. Agric. for 1917, p. 232. Burnett, Office Colorado 

 State Entom. Circular No. 25, 1918. 



20 Silver, Journ. Agric. Research, xxvm, 1133-1137, 1924. 



