No abstract

In much of the world, the persistence of long-distance migrations by mammals is threatened by development. Even where human population density is relatively low, there are roads, fencing, and energy development that present barriers to animal movement. If we are to conserve species that rely on long-distance migration, then it is critical that we identify existing migration impediments. To delineate stopover sites associated with anthropogenic development, we applied Brownian bridge movement models to high-frequency locations of pronghorn (Antilocapra americana) in the Greater Yellowstone Ecosystem. We then used resource utilization functions to assess the threats to long-distance migration of pronghorn that were due to fences and highways. Migrating pronghorn avoided dense developments of natural gas fields. Highways with relatively high volumes of traffic and woven-wire sheep fence acted as complete barriers. At crossings with known migration bottlenecks, use of high-quality forage and shrub habitat by pronghorn as they approached the highway was lower than expected based on availability of those resources. In contrast, pronghorn consistently utilized high-quality forage close to the highway at crossings with no known migration bottlenecks. Our findings demonstrate the importance of minimizing development in migration corridors in the future and of mitigating existing pressure on migratory animals by removing barriers, reducing the development footprint, or installing crossing structures.

No abstract

An increasing global demand for energy assures continued disturbance to previously undeveloped landscapes, but understanding broader impacts to wildlife remains elusive. Among groups of species most vulnerable to habitat disruption are those requiring large tracts of land. Pronghorn (Antilocapra americana) are an obligate to the open plains and basins that, similar to other transcontinental large herbivores, rely primarily on habitats where development of energy resources such as oil, natural gas, coal, wind, and solar are intensifying. To understand behavioral response to a burgeoning energy development project, we evaluated avoidance, displacement, and winter residency patterns of pronghorn in the southern Greater Yellowstone Ecosystem across a 15-year period using 171 collared individuals. Distance from natural gas well pads increased through time and was concurrent with declines in winter residency. Between 2005 and 2017, we found that (a) pronghorn avoidance of well pads likely increased by 408 m, (b) the overall displacement of pronghorn relative to well pads in the final year of study increased by 800 m, (c) the time pronghorn spent in the study area was reduced by 22% (nearly 1 month), and (d) the percentage of pronghorn leaving the study area increased by 57%. Such directional changes signal a strong behavioral response of an open-plain obligate to energy infrastructure, and together, these metrics indicate that pronghorn response to energy development involves both avoidance of infrastructure and partial abandonment of their traditional winter ranges. While comparable long-term data sets are generally unavailable for other functionally equivalent ungulate groups in similar ecological topographies of Asia, Africa, and South America, our study may serve as a reasonable surrogate and highlights that behavioral changes elicited from energy development which at first appear subtle can proliferate and may portend demographic consequences. K E Y W O R D SAntilocapra americana, avoidance, disturbance, indirect habitat loss, winter range

No abstract

No abstract

Sterilization of wild canids is being used experimentally in many management applications. Few studies have clearly demonstrated vasectomized and tuballigated canids will retain pair-bonding and territorial behaviors. We tested whether territory fidelity, space use, and survival rates of surgically sterilized coyote (Canis latrans) packs were different from sham-operated coyote packs. We captured and radio-collared 30 coyotes in December 2006. Sixteen of these animals were sterilized via vasectomy or tubal ligation, and 14 were given shamsurgeries (i.e., remained intact). We monitored these animals using telemetry and visual observations through 2 breeding seasons and 1 pup-rearing season from December 2006 to March 2008. Mean pack size was not significantly different between sterile and intact coyote packs. We found no difference in home range size between sterile and intact coyotes. We found differences in home range and core area overlap between sterile and intact coyote packs in some seasons; however, this difference may have existed prior to sterilization. Home range fidelity was not significantly different between sterile and intact coyotes. All coyotes had higher residency rates during the breeding season, with no differences between sterile and intact coyotes. Survival rates were correlated with biological season, but there were no differences in survival rates between sterile and intact coyotes. We concluded that surgical sterilization of coyotes did not affect territory fidelity, survival rates, or home range maintenance.

Surgical sterilization of coyotes (Canis latrans) reduced their predation rate on domestic sheep. We investigated whether sterilizing coyotes would similarly change coyote predation rates on pronghorn antelope (Antilocapra americana) neonates. From May 2006 to March 2008, we radio-collared 71 pronghorn fawns to determine survival rates in southeast Colorado, USA. During the first year of the study, all coyotes were reproductively intact. During the second year, we surgically sterilized 15 coyotes from 10 packs in the southern half of the study area, while nine coyotes from seven packs in the northern half were given sham sterilizations (i.e., remained reproductively intact). In addition, we estimated the availability of alternative prey and coyote density on both areas to evaluate predator-prey factors that could interact with the sterilization treatment. Using the known fate model in Program Mark, we constructed models with and without a treatment effect, plus year, area, individual covariates, alternative prey indices, and predator density to estimate pronghorn fawn survival rates. Results from model averaged parameter estimates and cumulative summer survival indicated coyote sterilization increased survival rates of pronghorn fawns by reducing predation rates of fawns. While fawn survival was higher overall in the north area, after treatment was applied, cumulative pronghorn fawn survival during the summer of 2007 in the south area was 242% higher for pronghorn fawns captured in sterile coyote territories (0.44; 79-day interval survival rate) compared to fawns captured in intact coyote territories (0.18). There was also a significant local area effect, but no relationship between fawn survival and individual fawn covariates of sex, birth weight, birth date, or age. No relationship was detected between fawn survival and lagomorph abundance index, rodent abundance index, or coyote density. Surgical sterilization of coyotes was useful in reducing predation rates on pronghorn fawns.