California Department of Fish and Wildlife

Wildlife Restraint Training

The basic techniques of animal capture and restraint are as old as humankind. People have used snares, nets, and brush corrals to capture animals for eons. As humans evolved, they gradually modified common hunting and killing techniques in order to capture, restrain, and domesticate animals.

These early peoples also used their knowledge of plants to devise "drug"-tipped darts, blown through a hollow tube, to chemically immobilize and kill prey. The science of chemical immobilization evolved rapidly in Africa during the 1950s, when researchers anxious to capture wildlife experimented with immobilizing drugs to reduce injuries and mortalities among the animals and to minimize the dangers to themselves. Chemical immobilization techniques proved to be highly successful and were later adapted for use with North American wildlife species.

Prior to 1970, California biologists primarily used manual or physical capture techniques, such as snares, culvert traps, and Clover traps. In order to collect samples, researchers often needed to restrain the animals using squeeze mechanisms, hobbles, or other methods. Together, the physical capture and restraint process were stressful and potentially dangerous to animals and humans alike.

The 1970's and 80's represented a period of important technological advances to the field of studying free-ranging wildlife populations. The use of radio-telemetry collars and new animal capture methods (such as net-guns, and refined chemical immobilization) that allowed a much greater ability to study wildlife populations and to assess the health and fate of individual animals. This lead to a period of more intensive wildlife management that included the capture, transport, and reestablishment of wildlife populations into historic habitat throughout the western United States.

For over thirty-five years, CDFW's Wildlife Investigations Laboratory (WIL) has developed and fine tuned drug protocols for immobilizing many of California's wildlife species. New drugs and drug combinations have been examined and field-tested. During this process, WIL researchers observed that chemical immobilization was not the universal solution for all wildlife capture situations. Drugs could knock the animal down but some of the drugs also depress the respiratory system. Respiration facilitates cooling, a critical factor when immobilizing animals that are already stressed or when ambient temperatures are high. Many times, it was clearly safer, more efficient, and less stressful to use some form of physical capture and restraint. So while the WIL was testing immobilizing drugs, it also used and refined a new generation of physical capture techniques involving drop nets, linear tangle nets, and net guns.

Today, CDFW biologists use a wide variety of capture methods, ranging from time-tested Clover and culvert traps to drugs and net-guns fired from a helicopter. The method chosen relates directly to the capture situation, the condition of the animal, ambient temperature, safety issues, and a wide variety of other considerations. This manual presents a wide range of physical and chemical capture techniques. Since each capture and/or restraint situation is unique, the methods described may require adaptation.

Increasing urbanization of wildlife habitat, more wildlife/human interactions, the pressing need for scientific research, and increased media attention on wildlife issues make it imperative to know how to safely and efficiently capture and handle wildlife. The WIL's Animal Restraint Class has evolved and been refined over a period of three decades and provides invaluable information and techniques for safely capturing and restraining wildlife.