TAYLOR, _Assistant Biologist,
Bureau of Biological Survey, U. S. Department of Agriculture_.

CONTENTS.

Page

Importance of rodent groups 1
Investigational methods 2
Identification 3
Description 5
General characters 5
Color 6
Oil gland 6
Measurements and weights 7
Occurrence 7
General distribution 7
Habitat 7
Habits 9
Evidence of presence 9
Mounds 9
Runways and tracks 10
Signals 11
Voice 12
Daily and seasonal activity 12
Pugnacity and sociability 13
Sense developments 14
Movements and attitudes 15
Storing habits 15
Breeding habits 16
Food and storage 18
Burrow systems, or dens 28
Commensals and enemies 33
Commensals 33
Natural checks 34
Parasites 35
Abundance 36
Economic considerations 36
Control 37
Summary 38
Bibliography 40

NOTE.--This bulletin, a joint contribution of the Bureau of Biological
Survey and the Arizona Agricultural Experiment Station, contains a
summary of the results of investigations of the relation of a subspecies
of kangaroo rat to the carrying capacity of the open ranges, being one
phase of a general study of the life histories of rodent groups as they
affect agriculture, forestry, and grazing.

IMPORTANCE OF RODENT GROUPS.

As the serious character of the depredations by harmful rodents is
recognized, State, Federal, and private expenditures for their control
increase year by year. These depredations include not only the attacks
by introduced rats and mice on food materials stored in granaries,
warehouses, commercial establishments, docks, and private houses, but
also, particularly in the Western States, the ravages of several groups
of native ground squirrels and other noxious rodents in grain and
certain other field crops. Nor is this all, for it has been found that
su