Douglas W. Smith Kerry M. Murphy Daniel R. MacNulty L. David Mech 2001 We studied wolf (Canis lupus) predation on elk (Cervus elaphus) in Yellowstone National Park from 17 March to 15 April 1997 (severe winter conditions) and from 2 to 31 March 1998 (mild winter conditions) 2-3 years after wolves were reintroduced to the park. Elk composed 91 % of 117 kills. Data comparisons for 1997 versus 1998 were: hunting success rate, 26% versus 15%; kill rate, 17.1 kg/wolf/day versus 6.1; percent of kill consumed in first day, 7 versus 86; percent femur marrow fat of adult kills, 27 versus 70; calf:adult ratios of kills, 2:33 versus 17:23; sex ratio of kills, 14M:19F versus 17M:6F; mean age of elk killed, males 6.1 years, females 15.2 versus males, 4.8, females 13.0. Winter severity influenced the wolf-elk relationship more than the naivete of the elk herd to predation by wolves. application/pdf 10.2307/3803048 en Wildlife Society Winter severity and wolf predation on a formerly wolf-free elk herd article