654 



ZOOLOGICAL SOCIETY BULLETIN. 



>*^ 



THIRTEEN-LINED SPERMOPHILE, 



right here that we evidently note one of tlie 

 phases of balance in animal life that we are en- 

 deavoring to illustrate in tlie exhibition of the 

 animals under discussion. 



The ground squirrels of the United States, 

 together with tlie members of the Mouse and 

 Rat Famil_y, the Muridce, stand as a positive 

 menace to the agriculturists — some of them 

 constituting a menace to 

 humanity generally. If 

 these creatures were not 

 kept in vigorous check 

 they would literally 

 overrun vast regions of 

 the globe. The march 

 of civilization has r e - 

 suited in the marked in- 

 crease of a number of 

 species that thrive upon 

 the products of tilled 

 soil. The ground squir- 

 rels, forming a large 



North American group, are jjarticularly connnon uials tliat constantly menace the welfare of man 

 in the western portion of the United States, kind, owing to their persistent multiplication, 

 where they are commonly called "gophers." They our series of the destructive rodents necessarily 

 have also been grouped under the title of sper- embraces a number of species of the rats and 

 mopliiles, — meaning seed-lovers. This title is mice, these representing the largest of the fami- 

 quite appropriate, as the vast majority of the lies among the rodents, or gnawing animals, the 

 species feeds principally upon grain and seeds. Muriclw. The conuuon rat, (Mux decumanus), 

 Thej;^ live in burrows in the prairie country, despite its insignificant size, must be rated as a 

 some in actual desert regions, and in the great distinctly destructive species, and one actually 

 wheat belts are altogether at home, in the midst dangerous to man. With the gradual solving of 

 of plenty. 



Of the sperniophiles north of INIexico, there 

 are thirty-one full species and forty-two sub- 

 species. In the cultivated areas their most de- 

 structive habit is the digging up of seed grain. 

 Yet it should be explained that some species eat 

 quantities of destructive insects, such as grass- 

 hoppers, beetles, cut-worms and crickets, and in 

 this way partly compensate the farmer for the 

 grain they devour. The ground squirrels or 

 sperniophiles {(re prolific, bringing forth seven 

 to ten young in a litter. Their enemies are the kangaroo rat. 



rodent-eating snakes, foxes, badgers, skunks, 

 hawks and owls. Of these little animals exhib- 

 ited in our series to demonstrate the destructive 

 species and their natural destroyers, the thir- 

 teen-lined spermopliile, (Citellus tridecemlinea- 

 tiis). is one of the smallest, though most widely 

 distributed species. The pattern is striking 

 and characteristic, consisting of pale yellow 

 bands, separated by rows of yellow spots on a 

 dark brown ground-color. 



The Rieliardson sjocrmophile, {Citellus rich- 

 nrdsoni), of northern Montana, North Dakota 

 and the region immediately northward as far as 

 the Saskatchewan, is another of the ground 

 squirrels in our special collection. It looks much 

 like a miniature prairie "dog," except for the 

 proportionally longer tail. It is notoriously 

 destructive to grain. 

 Like a number of other 

 species among the sper- 

 niophiles. it passes the 

 winter in a state of hi- 

 bernation, during which 

 ])eriod its blood circula- 

 tion is greatly retarded, 

 to such an extent, i n 

 fact, that a hibernating 

 squirrel might be mis- 

 taken for a dead crea- 

 ture. 



As examples of mam- 



