QO ECONOMIC MAMMALOGY 



quarantined for sheep scabies, but in 1915 all but one state and small 

 portions of two others were free from quarantine. In 1905, ten states 

 were quarantined for cattle scabies, but in 1915 all but a small por- 

 tion of one state were free from quarantine. 8 



Considerable has been learned about the diseases and parasites of 

 wild mammals in captivity, and, though "some of the morbid condi- 

 tions described'. . . are peculiar to captivity, yet it seems reasonable to 

 assume that many of the diseases found in captive animals occur also 

 in the wild." 9 There is increased activity among- fish and game com- 

 missions in the investigation of diseases and parasites of wild animals 

 in ferae naturae, at least one state commission, that of California, hav- 

 ing employed for the purpose experts in pathology, parasitology and 

 chemistry. 10 



Though diseases of wild mammals under natural conditions have 

 not been so fully investigated as have those of domestic stock, it is 

 known that many of the species are subject to serious diseases, and 

 probably no species is entirely free from them. Some of the diseases 

 of domestic stock also affect members of the deer family and wild 

 species of goats and sheep. Diseases that attack the more useful wild 

 mammals, as with those that affect domestic stock, may in a general 

 way be considered detrimental to human interests, but this is not al- 

 ways or altogether true. Domestic stock, under human control, may be 

 limited in reproduction and never become too numerous. It is not so 

 easy to do this with wild mammals. Even useful wild animals, if en- 

 tirely protected from natural enemies, disease and bad weather, might 

 increase to such an extent as to become a menace. Deer, usually too 

 scarce to be harmful, have been known to become so numerous under 

 protection as to be somewhat destructive to garden and other crops. 

 However, their numbers are easily reduced by removing restrictions 

 upon hunting. 



A few rabbits are not usually considered particularly destructive, 

 but under favorable circumstances their natural high fecundity may be 

 greatly increased and their mortality rate lowered, a larger percentage 

 of the young reaching the adult stage, whereupon they become a seri- 

 ous pest. As though to exhibit her wisdom, nature has provided that 

 in their natural haunts, when rabbits become overabundant, they are 

 assailed by epidemics that destroy them in large numbers, thus keep- 

 ing them within reasonable bounds, so that they do not become so 



8 Mitchell, Yearbook U. S. Dept. Agric. for 1915, PI. 18, opp. p. 161. 

 8 Fox, Disease in captive wild mammals and birds, Philadelphia, 1923. 

 10 California Fish and Game, xv, 135, 1929. 



