Mammal Damage Unit Records --

The Section of Mammal Damage Control Research has been an integral part of the NWRC and its predecessor agencies’ mission since the late nineteenth century. The Unit can trace its roots back to the USDA Bureau of Biological Survey’s (BBS) investigations into wildlife food habits, migration, species distribution and the effects of mammal damage to agricultural and forestry resources. Research and develop methods first began in 1888 to control injurious rodents and predators. In 1929, the Division of Predatory Animal and Rodent Control was officially established under the BBS and by 1934 the unit was known as the Section of Predator and Rodent Control. In 1940, the division was reassigned to the USDI Fish and Wildlife Service. In 1985, the Unit was transferred back to the USDA/APHIS.

Beginning in the 1940s, the Mammal Damage Unit focused on controlling damage caused by various rodents such as pocket gophers, which caused extensive damage to buried wire and cables. For nearly 50 years (1940s-1990s), the Unit collaborated with telecommunications and energy industries to evaluate cable resistance to rodent damage. Researchers at the DWRC conducted experiments on poisons and repellents for insulating cable materials, but found them to be ineffective due to the hazards of leaching materials into the soil and the ability of gophers and other rodents to avoid getting treated material in their mouths while gnawing on cables. By the 1950s, DWRC researchers were conducting experiments with herbicides, which did not kill the rodents by direct chemical effect but by removal of their food supply. This method was then adopted by the U.S. Forest Service to accomplish both weed and gopher control in range improvement programs.

During the 1960s, researchers tested repellents for Norway rats, squirrels, and mice. The Unit also conducted biting force tests on new designs of cable for Bell Laboratories. During the 1980s-early 1990s, these methods were used to test thousands of cable samples from companies seeking evaluations of their designs. DWRC scientists also made additional observations on pocket gopher biology during these studies, augmenting laboratory studies with field studies conducted at Grand Mesa and Black Mesa, Colorado. Testing of Gophacide (DRC-714) to control pocket gophers, house mice, and rats began in 1961. DRC-714 was registered in 1969 for pocket gopher control, but canceled in 1974. Also during the 1960s-1970s, the Unit studied the habits and physiology of rats damaging sugar cane and other crops in Hawaii. DWRC researchers began investigating black-tailed jackrabbit damage to agriculture during this time as well, studying population dynamics and behavior as well as testing several methods of chemical control. The Unit also tested pesticides for secondary hazards to birds and to both wild and domesticated non-target species.

In addition to rodent control, predator control, especially for coyotes, has been a long-standing mission of the Unit. From the 1960s through the 1990s, DWRC/NWRC researchers carried out studies on coyote food habits, diseases, scare devices, trapping methods, and coyote-rodent relationships. The Unit studied responses of coyotes to chemical attractants to improve the performance of the M-44 device and researched chemicals to alter reproductive rates in coyotes. The Unit also evaluated damage management methods for established wolf populations.

Over the years, the Unit studied mammals on public lands, including investigations into how various species live, their life histories, habits, and food and space requirements. They also worked to develop new predator management tools to replace traps and toxicants on public lands. The Mammal Damage Control Unit conducted field investigations into the effect of herbicides on forest and range wildlife, relations of squirrels, mice, deer, pine voles, and mountain beavers to forest tree regeneration, whether bear damage to timber is a learned behavior or an evolutionary trait, food requirements of big game species, rodent predation on protected species, nutria and muskrat damage to marsh ecosystems, and human perceptions of wildlife damage and control. The Mammal Damage Unit also researched physical barriers and nonlethal means to protect trees from mammal damage. Beginning in the 1970s, the Unit cooperated with Dupont to develop Vexar plastic seedling protectors to protect trees from mammal damage and developed tubing to protect roots of seedlings from gopher damage.

In addition to private companies, the Unit worked collaboratively on mammal damage studies with other partners including universities, other government agencies, non-governmental organizations and the U.S. military.