Surgical sterilization of coyotes to reduce predation on pronghorn fawns
Coyote (Canis latrans) predation accounts for the majority of neonatal pronghorn (Antilocapra americana) mortality in many areas and may influence local population declines. Current techniques used to manage coyote predation on wildlife species generally focus on lethal control methods. However, these methods may be controversial to the general public. Coyote sterilization is an alternative predation control method which is more acceptable to the public and has been shown to be effective in reducing sheep predation. We hypothesized that surgical sterilization of coyotes may increase pronghorn fawn survival; in the same way it reduces coyote predation on domestic sheep. Sterilization reduces the energetic need to provision coyote pups, which may decrease the predation rate on fawns by sterile coyotes. We employed tubal ligation and vasectomy of captured coyotes to maintain pair bonds and territoriality. We monitored pronghorn fawns by radio telemetry for one year pre-treatment and coyotes and pronghorn fawns one year post-treatment. We also examined the effects of sterilization on coyote territorial maintenance and survival. Survival of fawns captured in sterile coyote home ranges was higher than survival of fawns captured in intact home ranges (P = 0.078). We also found that fawn survival was consistently higher in the northern part of the study site (P = 0.081). A severe winter followed by a wet spring in 2007 did not reduce fawn survival and may have increased fawn survival (P = 0.364); however, our sample sizes did not allow us to detect significance in this relationship. Our results also supported the hypothesis that sterilization, while keeping hormonal systems intact, did not change coyote territorial behaviors. Sterile coyote packs were the same size as intact packs (P = 0.554). Sterile and intact coyote packs maintained similar home range sizes in all seasons tested (P Â¡Ã? 0.556). We found differences between home range and core area overlap of sterile and intact packs in some seasons, but this trend appeared to exist before the coyotes were treated. Residency rates were similar for sterile and intact coyotes (P = 0.406). We recommend coyote sterilization as a tool to boost pronghorn fawn survival in areas where fawn survival is a critical factor in pronghorn population persistence. Because these techniques have been tested under few circumstances, we recommend careful monitoring in future coyote sterilization programs.
School:Utah State University
School Location:USA - Utah
Source Type:Master's Thesis
Keywords:antilocapra americana canis latrans coyote management fawn survival predation surgical sterilization
Date of Publication:05/01/2009