Selectivity and Effectiveness of Pan Tension Devices for Coyote Foothold Traps

Abstract

Data were collected on the numbers of coyotes (Canis latrans) and nontarget animals that stepped on standard traps and traps equipped with shear-pin, curved leaf spring, or steel tape tension devices and were captured or excluded. The modified 3N-M Victor steel foothold traps were about three times more effective than standard traps for excluding kit (Vulpes macrotis) and swift (V. velox) foxes, gray foxes (Urocyon cinereoargenteus), striped skunks (Mephitis mephitis), opossums (Didelphis virginiana), and jack rabbits (Lepus californicus). Coyote capture rates in initial field tests were lower for modified traps than standard traps when set in wet clay or alkali soils. Shear-pin and leaf spring devices were then modified and zinc-plated to reduce rusting caused by moisture and to improve trap performance. Exclusion rates (percentage of animals that stepped on pans and were excluded) in subsequent field tests for all designated nontarget animals for the wet soil test were 92, 100, 95, and 6 for shear-pin, leaf spring, steel tape, and standard traps, respectively. Coyote capture rates with the improved devices in wet areas with clay or alkali soils were 87, 92, 84, and 98% for shear-pin, leaf spring, steel tape, and standard traps, respectively. The improved devices functioned adequately for use in coyote trapping activities. J. WILDL. MANAGE. 48(3):700-708 Steel foothold traps are used for harvesting furbearers and for removing coyotes and other predators from livestock depredation areas. Private fur trappers usually attempt to capture smaller furbearers as well as coyotes, but U.S. Fish and Wildlife Service (USFWS) Animal Damage Control Program (ADC) efforts are hampered when traps set for coyotes are sprung by other animals. Because traps are an important tool in the ADC program, efforts were initiated at the Denver Wildlife Research Center (DWRC) to make trapping for depredatory coyotes more efficient and selective (Linhart et al. 1980). Trap selectivity and efficacy are major issues raised by proponents of restricting or prohibiting use of steel traps (Dixon 1930, Atkison 1956, Gipson 1975, Singer 1975, Nichols 1976, Parsons 1977, Howard 1979, Todd 1980, Schmidt 1981). T ese issues are also of concern to the