مرگ و میر دام در مزارع گاو با گرگ مزمن (کانیس لوپوس) یغمای در غرب منطقه دریاچه های بزرگ (WGLR)
Abstract: Gray wolf (Canis lupus ) depredation on beef calves has been studied extensively in recent years. As wolf populations increase throughout the United States there is a corresponding increase in wolf/livestock interactions. Most research concentrates on summaries of reported depredations and surveys of producers affected by depredations. The objective of this study was to present data on the fate of beef calves on 3 farms in Minnesota and Wisconsin over a 2-year period. Predator presence/absence was studied as an indicator of potential depredations. Also, data are presented comparing 2 techniques that may aid researchers and livestock producers with monitoring livestock. Radio telemetry collars and ear tags were applied to beef calves on 3 farms in northern Minnesota and Wisconsin during the spring and summer of 2006 and 2007. During this time, 4 calves were killed by wolves on the study farms. Wolves did not appear to be selecting the youngest calves and most depredations occurred from April through July. Although not statistically significant, wolf sign appeared at slightly higher rates on study farms than on land adjacent to these farms. Predator sign, including coyote ( Canis latrans ) and black bear (Ursus americanus ), appeared more often in the heavily forested areas of the farms. Radio collars and radio ear tags were helpful for monitoring beef calves during this study. Radio collars had much longer transmitting distances than ear tags (2.3 ± 0.8 miles and 0.4 ± 0.2 miles, respectively). Radio ear tags had a potential for causing beef calves\' ears to droop or were ripped out, possibly lowering their market value. Currently, cost is prohibitive for the widespread use of radio transmitters for monitoring livestock but as the price of new technologies decreases, transmitters may become an integral part of livestock production on farms with chronic wolf depredation.