Arizona \ 
Exp. Sta. / 
LIFE 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 Avas noted about the habitations of the banner-tailed 
kangaroo rat (Dipodomys spectabilis spectabilis Merriam), although 
it was observed also that jack rabbits of two species (Lepus calif or- 
nicus eremicus Allen and L. alleni 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. 2 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 
spectabilis spectabilis 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- 
nryidse), 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: (b) the pocket mice {Perogna- 
thus). which are considerably smaller than the kangaroo rats ami 
2 In addition to assistance rendered by officials of the 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 Loftfield, 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 indehted to William Nicholson, of Con- 
tinental. Ariz., for many courtesies extended in connection with work on the Reserve. 
