The Effectiveness of Nos. 120 and 220 Conibear Traps for
Small Mammals
EDWARD P. HILL
U.S. Fish and Wildlife Service, Mississippi Cooperative Fish and Wildlife
Research Unit, P.0. Drawer BX, Mississippi State, MS 39762
Poor nesting success (<10%) in most of the Prairie Pothole Region continues to dim prospects for recovery of North American waterfowl numbers to desired levels. Much of the loss has been attributed to nest predation by five species of small mammals, and effective methods of controlling them on some sites are needed. Program costs for controlling small mammals with traps have often been prohibitive. Traps often became inoperable during rainy or freezing weather. In addition, concern about injury, capture of nontarget species, and prolonged suffering of animals in traps has been the major source of public opposition.
We evaluated several traps in baited sets to determine effectiveness, selectivity, humaneness, and efficiency on sites in Alabama containing wintering shorebirds and waterfowl. Numbers 120 and 220 Conibear traps in cubby boxes were compared to standard and modified No. 2 coil spring leghold traps. We presumed that cubby boxes would be both weather- and dog-proof.
Catches per trap night in standard coil spring leghold traps and Conibear traps were similar, but the Conibears were 13% more efficient than regular coil spring leghold traps in catches per trap closure. The No. 220 Conibear was effective for small mammals but, because of its large size, the 220 Conibear also caught mid-sized free-ranging canids. The No. 120 Conibear was equally effective in catching small mammals but appeared to exclude the mid-sized canids. Raccoons (Procyon lotor) and opossum (Didelphis virginiana) were the common species on the study areas and composed 87% of the catch in No. 220 and 93% in No. 120 Conibear. These traps have also been proven effective for skunk (Mephitis spp.) on two study sites in Montana.
Advantages of the Conibear cubbies over leghold traps were as follows: (1) they were more easily baited, set, and checked; (2) they were less likely to become inoperative because of weather extremes; (3) they did not appear to present a hazard to waterfowl or shorebirds; and (4) death occurs quickly. Although the No. 120 Conibear was effective for southern (smaller) raccoons and opossum, and did not catch mid-sized dogs, the No. 220 Conibear appears better suited for northcentral areas of the United States where nest predators tend to be larger and where there are typically fewer feral and free-ranging dogs. The Conibear cubby boxes appear to have potential as a tool for controlling several of the small mammals that prey on eggs and hens of waterfowl and other ground nesters. Their efficiency for taking spotted skunk (Spilogale spp.), mink (Mustela vison), and certain ground squirrels should be field tested in areas where these species are serious nest predators.
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