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Yellowstone National Park Report

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Fifty-four healthy coyotes (Canis latrans) and 32, 8-12 week old pups captured at dens were radio­tagged in the Lamar Valley and Blacktail Plateau areas of the northern range of Yellowstone National Park. Seven of the 40 captured in the fall were 6 month-old pups which suggest slow population productivity. Adults range in age from 1 to 12 years and averaged nearly 4 years old. Territorial packs in both study areas are adjacent, non-overlapping, contiguous, and averaged 15 km2/ We estimate that 85 to 90% of coyotes on the northern range belong to packs. A territorial group or pack during the winter consists of 2 alpha individuals, 2 or 3 beta adults, and 2 or 3 adult-sized pups (average pack size = 7). Nine adults were killed (2 mountain lion [Felis concolar], 2 road-kill, 2 shot, and 3 unknown) which equates to a 15% annual mortality rate. Eleven of 36 pups have died between the ages of 3 and 9 months old. Population productivity ranges from 2.0 to 2. 7 pups recruited per territory. The reproductive failure rate among breeding groups averaged 15% during 1990 and 1991. Initial coyote density estimates are 0.09 per km2. Intensive foraging observations were conducted from January through June 1991. In 353 hours of focal observations 427 capture attempts were made on small mammal prey with 162 (38%) successful. Habitat type played a key role in the success rate. Mesic meadows had the highest capture rates followed by willow/meadow habitats and sage habitat. Small mammals, especially voles (Microtus spp.), dominate the diet with ungulate remains becoming important in May through July, presumably elk (Cervus elaphus) calves and late winter, mostly scavenging. We have observed numerous successful and unsuccessful predation attempts on ungulates in our study areas. Coyotes appear to impact ungulate numbers in 3 ways: predation on calves and fawns shortly after birth (up to 8 weeks), predation on short-yearlings and adults during winter, and indirect impact from harassment of other predators at ungulate-kills. Coyotes may be the major ungulate predator on the northern range due to cooperative social and foraging behavior, their ability to take advantage of vulnerable ungulates, and their high population levels. Wolf (Canis lupus) extirpation has probably resulted in high coyote population densities.