DANGER OF INTRODUCING NOXIOUS ANIMALS AND BIRDS. 91 



toward the west, although the minas have been carried in the ojjposite 

 direction to New Zealand and the Hawaiian Islands, and flying foxes 

 are likely to extend northward and eastwarc I . The main danger for the 

 United States lies in si)ecies native to central and southern Europe 

 and western Asia, but tropical species, particularly of India, niiglit 

 become acclimated in the Southern States. In order to show how 

 these animals and birds have already spread, and the damage they 

 have done, it will be necessary to refer briefly to the history of each 

 species. 



RATS AND MICE. 



Rats and mice are among the greatest pests with which man has to 

 contend, and the annoj^ance and damage which tliey occasion are 

 beyond computation. They are ubicpiitous, abundant alike in Ihe 

 largest cities and on the most distant islands of the sea. They have 

 not been intentionally introduced anywhere, but have found tlieir 

 waj' by means of vessels to all parts of the earth. Small islands, pop- 

 ulated with rats from wrecks, or otherwise, are occasionally overrun 

 by these animals. On the island of Aldabra, already mentioned, rats 

 fairly swarm, and are very destructive to the gigantic native land 

 tortoise, eating the young as soon as they are hatched. Sable Island, 

 off the coast of Nova Scotia, has suffered from several plagues of rats, 

 and it is said that the first superintendent of the light station and his 

 men were at one time threatened with starvation owing lo the inroads 

 made on their stores by rats. 



The covimon broini rat. — The common brown rat, known also as the 

 wharf rat and Norway rat {Mus decumanus), was originally a native 

 of western Cliina,^ and until two hundred years ago was unknown in 

 Europe or America. It is very prolific, producing from four to twelve 

 young at a birth scNeral times a year, and has spread so rapidly that 

 at the present time it is nearly cosmopolitan. In the autumn of 1727 

 large numbers of brown rats entered Euro^je by swimming across the 

 Volga, and, gaining a foothold in the province of Astrakan in eastern 

 Russia, siiread westward over central Europe. Five years later (17o2) 

 they reached England by vessels from western India. The brown rat 

 appeared in east Prussia about 1750, and in Denmark and Switzerland 

 in 1809. It reached the eastern coast of the United States about 1775, 

 and in. 1825, according to Sir John Richardson, had extended as far 

 west in Canada as Kingston, Ontario. By 1855 it was abundant at sev- 

 eral points on the Pacific coast, including San Fi-aucisco, Cal. ; Astoria, 

 Greg., and Steilacoom, Wash., and its range on the west coast now 

 extends as far north as Alaska, at Sitka, Kadiak, and even Unalaska. 



' Blanford (Mammals of India, 1888-1891. p. 409), who gives Chinese Mongolia as 

 its probable original habitat, states that it is not indigenous to India, and is 

 unknown in Persia and Afghanistan, but suggests that it will probably be intro- 

 duced into the two latter countries as soon as wheeled vehicles take the place of 

 pack animals. 



