RODENTIA 279 



eating small animals caught in traps. 24 Western desert mouse (P. m. 

 sonoriensis) : "besides insects, quantities of Xanthium seeds are eaten 

 by this mouse," and it ate many cotton rats which were caught in 

 traps. 25 San Clemente mouse (P. m. dementis), "feeds on the ripe 

 fruits of the prickly pear (Ofnmtia)."** LeConte white-footed mouse 

 (P. m. gracilis) : 2 stomachs contained green vegetation and insects. 27 

 Rowley white- footed mouse (P. boylii rowleyi) , food "consists largely 

 of juniper berries . . . but acorns and pine nuts are eaten while they 

 last." 28 



The white-footed mice are hosts of the spotted fever ticks, and, as 

 they, enter occupied dwellings, they are a special source of danger in 

 fever-infested districts. 29 They are not usually found in buildings 

 which harbor the European mouse (Mus musculus). The mound made 

 by the old-field mouse (P. polionotiis) is very large for so small an 

 animal. "At times it doubtless contains several large cupfuls of soil," 

 while some of the burrows are nearly or quite a foot deep. 30 "Little 

 is known of the food habits of this species, but it is believed to feed 

 largely on the seeds of grasses, weeds and grain; several stomachs 

 from Abbeville contained remains of blackberries, with other finely 

 chewed food." 31 



"Cotton rats (Sigmodon}, when numerous in cultivated ground, 

 often prove very destructive to crops, not only cotton, but all grains, 

 alfalfa, hay and many other farm products. But for owls and such 

 enemies they would be a serious menace to agriculture." 32 The natural 

 food of the northern cotton rat (S. hispidus hispidus) consists of 

 "stems and seeds of wild grasses and other plants," but it takes also 

 grain, where available. 33 The Texas cotton rats (S. h. texianus) "be- 

 come so numerous as to suggest the plagues of voles that from time 

 to time have overrun parts of Europe," and they then do much damage 

 to the cotton crops. During the cycle of abundance in Bexar County, 

 Texas, from 1889 to 1891, hawks, owls, weasels and skunks became 

 more abundant and preyed upon the rats ; rattlesnakes and other snakes 



24 Mearns, U. S. Natl. Museum Bull. No. 56, p. 389, 1907. 



25 Mearns, U. S. Natl. Museum, Bull. No. 56, p. 394, 1907. 



26 Mearns, U. S. Natl. Museum, Bull. No. 56, p. 400, 1907. 



27 Johnson, Journ. Mammalogy, in, 37, 1922. 



28 Bailey, N. Amer. Fauna, No. 25, p. 98, 1905. 



29 Birdseye, Farmers' Bull., No. 484 p. 29, 1912. 



30 Sumner and Karol, Notes on the burrowing habits of Peromyscus polionotus, 

 Journ. Mammalogy, x, 214, 1929, citing Howell. 



31 Howell, N. Amer. Fauna, No. 45, pp. 44-46, 1921. 



32 Bailey, Animal life of Carlsbad Cavern, p. 81, 1928. 



33 Howell, N. Amer. Fauna, No. 45, p. 52, 1921. 



