#91-80 “Production and yield of deer on the Hopland Field Station”
Dale McCullough, Dept. of Environmental Science, Policy, & Management, UC Berkeley
In a 19-year study at Hopland, research tested the effect of removal of does on the yield of bucks in annual public hunting seasons for black-tailed deer. Number of bucks harvested during the 7-year-long treatment period (when 20 or 30 does, not normally hunted at Hopland, were removed) was significantly greater than during the pre-treatment and post-treatment “control” periods. Thus, doe harvest increased buck yield, apparently through lowering population density. At the end of the treatment period, combined buck harvest and doe removal comprised about 21% of the estimated pre-hunt population. Increased buck harvest occurred despite its coinciding with a 6-year drought. Bucks taken during the treatment period were younger and weighed less than those taken during control periods, but they had larger antlers.
#54-92 “Determining Which Coyotes Prey Upon Sheep”
Michael Jaeger, USDA National Wildlife Research Center, Denver, CO
Live-capture and radio-telemetry tracking of adult coyotes at Hopland, coupled with surveillance of pastures to find recently coyote-killed sheep and lambs, suggested that the coyotes primarily responsible for sheep losses were territorial, breeding adults. Further, breeding males tended to be more highly associated with depredation than were their mates. Breeding adults were difficult to control by means of traps, snares, calling and shooting, or other methods except during the pup-rearing season (April through August). On 2 occasions, removal of one member of a territorial pair during this season caused a surviving member to leave its territory, where it was successfully trapped.