Rxp^Ste } LI^^ HISTORY OF THE KANGAROO RAT. 3 



For some years an intensive study of the forage and other vegeta- 

 tive conditions of this area has been made, the permanent vegetation 

 quadrat, as proposed by Dr. F. E. Clements (1905, 161-175), being 

 largely utilized. During the autumn of 1917 representatives of the 

 Carnegie Institution and the Arizona Agricultural Experiment Sta- 

 tion visited the Eeserve and were impressed with the evidence of 

 rodent damage to the grass cover. The most conspicuous appearance 

 of damage was noted about the habitations of the banner-tailed 

 kangaroo rat {Dlpodomys spectabilis s-pectabilis Merriam), although 

 it was observed also that jack rabbits of two species {Lepus calif or- 

 ndcus- ere?nicus Allen and L. aUeni alleni Mearns), which were very 

 abundant in some portions of the reserve, were apparently affecting 

 adversely the forage conditions in particular localities. Accordingly, 

 the Biological Survey, the Agricultural Experiment Station of the 

 University of Arizona, the Carnegie Institution of Washington, and 

 the U. S. Forest Service have undertaken a study of the relation of 

 the more important rodents to the forage crop of the Range Reserve 

 in Arizona. 



The present paper is a first step in this larger investigation.^ In 

 this work the authors have made no attempt to deal with the taxo- 

 nomic side of the kangaroo rat problem. It is not unlikely that 

 intensive studies will show that the form now known as Dipodomys 

 g i spectabilis spectaMlis is made up of a number of local variants, some 

 of them perhaps worthy of recognition as additional subspecies. But 

 it is felt that the conclusions here reached will be little, if at all, 

 affected by such developments. 



Color descriptions are based on Ridgway's Color Standards and 

 Color Nomenclature published in 1912. 



IDENTIFICATION. 



There are only three groups of mammals in the Southwest having 



external cheek pouches. These are {a) the pocket gophers (Geo- 



[i myidee), which have strong fore feet, relatively weak hind feet, and 



short tail, as compared with weak fore feet, relatively strong hind 



[feet, and long tail in the other two; (&) the pocket mice {Perogna- 



\thus), which are considerably smaller than the kangaroo rats and 



= In addition to assistance rendered by oiBcials of tlie Biological Survey and the Uni- 

 versity of Arizona, which is hereby acknowledged, the authors are Indebted to the follow- 

 ing persons for helpful suggestions and assistance : G. S. Miller and J. W. Gidley, of the 

 U- S. National Museum ; Dr. Frederic E. Clements and Gorm Loftfleld, of the Carnegie 

 Institution ; Morgan Hebard, of the Academy of Natural Sciences of Philadelphia ; James 

 T. Jardine and R. L. Hensel, both formerly connected with the U. S. Forest Service ; and 

 R. R. Hill, of the Forest Service. They are also indebted to William Nicholson, of Con- 

 tinental, Ariz., for many courtesies extended in connection with work on the Reserve. 



