Evaluate Differential Recruitment among Fawning Areas

We are collaborating with the University of Idaho and Yellowstone Ecological Research Center to conduct a three-year study of the ecological interactions between wolves, coyotes, and pronghorn to determine if spatial and temporal variations in coyote and wolf densities and use areas contribute to differential survival/recruitment among pronghorn fawning areas. Coyote predation is a significant limiting factor for Yellowstone pronghorn, contributing to substantial fawn mortality, decreased recruitment, and some adult mortality. Coyote numbers are believed to be at unnaturally high numbers on the pronghorn winter range owing to plentiful elk carrion from hunters, starvation, and wolves. Thus, it may be beneficial for pronghorn to migrate elsewhere for fawning to escape heightened predation risk to young. Also, there is speculation that the restoration of wolves in 1995–1996 could indirectly contribute to higher recruitment of Yellowstone pronghorn by reducing the resident coyote population on the pronghorn summer range. Coyote densities were relatively high in areas used by pronghorn prior to wolf restoration; particularly in summer range areas further from the park boundary where opportunistic hunting of coyotes occurred. Wolves kill coyotes through inter-specific aggression and have purportedly reduced the resident coyote population by approximately half in some areas of the migrant pronghorn summer range where wolf densities are highest. To date, wolf predation on pronghorn adults and fawns appears insignificant. It is uncertain if wolf-induced mortality of coyotes has been high enough to reduce coyote densities to levels where predation on fawns in the migratory summer range would be significantly reduced. However, if wolves contribute to higher recruitment of migratory pronghorn by reducing coyote density, and this differential reproductive success is sustained over time, then the migratory portion of the population will likely increase.