[ANIMALS ON THE CONTROL PROGRAM]
Certain species of the rodents that in large numbers infest lands of value for crop or forage production must be eradicated locally to meet the requirements of agriculture and forestry. Those that figure most largely in the cooperative control operations in one part or another of their ranges are the prairie dogs, ground squirrels, pocket gophers, jack rabbits, porcupines, and native and introduced rats and mice. Other groups that locally become unduly numerous and destructive may also on occasion come within the control program. It would be impossible to eradicate everywhere the ground squirrels, prairie dogs, and other rodents that range over vast areas of relatively worthless lands, and such action is not desirable, even on the public domain. In areas of economic importance, however, definite tracts are established where the rodents can be kept under thorough control, and operations are extended sufficiently to prevent reinfestation.
The control of such predatory wild animals as coyotes, wolves, mountain lions, and bobcats is concentrated on areas where serious damage is being done to domestic stock, poultry, and game. Bears are not subject to control except when individually injurious to livestock or property.
OTHER FORMS SUBJECT TO CONTROL
Though the chief control work directed by the Biological Survey is concerned with injurious rodents and predatory mammals, it sometimes becomes necessary to investigate cases of damage by other classes of animal life, including moles, crawfishes, and land crabs, and to recommend measures for their control.