Trap-related injuries to gray wolves in Minnesota

Gray wolves (Canis lupus) captured in traps with toothed jaws offset 1.8 cm incurred fewer injuries than those captured in 3 other types of steel traps. Few wolves seriously damaged canine or carnassial teeth while in traps. J. WILDL. MANAGE. 50(1):90-91 Van Ballenberghe (1984) noted that 44% of 109 wolves he captured in steel traps had severe foot injuries, and 46% broke teeth while in traps. However, he did not compare injuries caused by different types of steel traps or describe damage to dentition. Herein we describe the incidence and types of injuries incurred by wolves captured in 4 types of steel traps. We appreciate the field assistance of L. R. Jewett, R. K. Markl, T. J. Meier, M. E. Nelson, H. Niskanen, and J. Renneberg. The research was supported by the Minn. Dep. Nat. Resour., the U.S. Fish and Wildl. Serv., and the U.S. For. Serv. North Central For. Exp. Stn. During 1968-85, 375 adult (_1 year) and 179 juvenile wolves were trapped in northern Minnesota for radio-telemetry studies (Mech 1980, Fritts and Mech 1981, Berg and Kuehn 1982, Fuller and Kuehn 1983) and control of livestock depredation (Fritts 1982, Fritts et al. 1984). Wolves were captured in Oneida Newhouse double-longspring traps with 4 types of jaws: No. 4 (smooth jaws not offset), No. 4 OS (smooth jaws offset 0.2 cm), No. 14 (toothed jaws offset 0.7 cm), and No. 14 OS (custommade toothed jaws offset 1.8 cm; Kirsh Foundry, Inc., Beaver Dam, Wis.). Injuries to feet and legs were categorized similar to Van Ballenberghe (1984): Class 1 = no visible injuries or slight swelling; Class 2 = cut(s) 2.5-cm long and/ or 1 injured (fractured or dislocated) phalanx or metacarpal; and Class 4 = >2 injured phalang s or metacarpals, and/or injured carpal(s), radius, or ulna. Chi-square tests were used to identify ageand trap-specific differences in inju y rates. The incidence of minor (Class 1 and 2) vs. more serious (Class 3 and 4) injuries was examined by wolf age and trap type. Fewer (P 2.5-cm long (8%) than the smoothjaw d traps (28-30%) (P < 0.01), probably because the traps' teeth prevented the wolves' feet from slipping in the trap jaws. However, No. 14 traps injured phalanges more often (19%) tha did the smooth-jawed traps (6-9%) (P < 0.05). No. 14 OS traps also minimized cuts (0%), but unlike No. 14 traps, they did not injure phalanges (0%), probably because the wide offset prevents the shearing action that occurs when the teeth of No. 14 traps pass under the opposing jaw. In juvenile wolves No. 4 OS traps caused more cuts (20%) than did No. 4 or 14 traps (36%) (P < 0.05). We did not record data concerning edema in feet of trapped wolves, but 'Mailing address: U.S. Fish and Wildlife Service, North Central Forest Experiment Station, 1992 Folwell Avenue, St. Paul, MN 55108. 2 Mailing address: North Central Experiment Station, University of Minnesota, 1861 E. Highway 169, Grand Rapids, MN 55744.