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Yellowstone National Park Report

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Sixty healthy coyotes Canis latrans and 53, 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. Adults range in age from 1 to 12 years and averaged 3.3 years old. Territorial packs in both study area are adjacent, non-overlapping, contiguous, and averaged 15 km2. Based on information the last four winters and data collected from 1946 to 1949, territorial areas are traditional and have changed little in the last 45 years. 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 was 6.3 for Lamar Valley and 4.6 for Blacktail Plateau. Mean litter size for 1990 through 1994 was 4.1, 5.7, 6.5, 3.3, and 2.3 for those five years. Initial density estimates are 1.4 coyotes per square mile. Preliminary scat analysis suggests that small mammals, especially voles, dominate the diet with ungulate remains becoming important in May through July (presumably elk calves) and late winter (mostly scavenging). Graduate students Eric Gese, Kezha Hatier, and Scott Grothe have finished their data collection and are analyzing data and preparing manuscripts. More than 2500 hours of foraging observations were conducted from January 1991 through June 1993 resulting in data collection on more than 4400 predation attempts on small mammals. Eight hundred and fifty hours of den observations were completed during 1992 and 1993. Beta pack members were observed to bring food to pups and protect den sites from intruders. Coyote behavior and ungulate mortality data were collected on 80 carcasses found or translocated during the 1992-93 and 1993-94 winters. Coyotes were observed at these carcasses for 484 hours. Alpha males usually feed first at carcasses followed by alpha females, beta individuals and pups. Those first to feed typically eat the internal organs and muscle tissue first. Betas and pups are left to feed mostly on bones and hide. Five successful and 4 unsuccessful predations by coyotes on ungulates have been seen. 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 extirpation has probably resulted in high coyote population densities and coyotes have, at least, partially slid into this vacant niche.