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Apex predators can shape communities via cascading top-down effects, but the degree to which such effects depend on predator life history traits is largely unknown. Within carnivore guilds, complex hierarchies of dominance facilitate coexistence, whereby subordinate species avoid dominant counterparts by partitioning space, time, or both. We investigated whether a major life history trait (hibernation) in an apex carnivore (black bears Ursus americanus) mediated its top-down effects on the spatio-temporal dynamics of three sympatric mesocarnivore species (coyotes Canis latrans, bobcats Lynx rufus, and gray foxes Urocyon cinereoargenteus) across a 15,000 km 2 landscape in the western USA. We compared top-down, bottom-up, and environmental effects on these mesocarnivores using an integrated modeling approach. Black bears exerted top-down effects that varied as a function of hibernation and were stronger than bottom-up or environmental impacts. High black bear activity in summer and fall appeared to buffer the most subordinate mesocarnivore (gray foxes) from competition with dominant mesocarnivores (coyotes and bobcats), which were in turn released by black bear hibernation in winter and early spring. The mesocarnivore responses occurred in space (i.e., altered occupancy and site visitation intensity) rather than time (i.e., diel activity patterns unaffected). These results suggest that the spatio-temporal dynamics of mesocarnivores in this system were principally shaped by a spatial predator cascade of interference competition mediated by black bear hibernation. Thus, certain life history traits of apex predators might facilitate coexistence among competing species over broad time scales, with complex implications for lower trophic levels.

Translocation is an important management tool that has been used for >50 years in Arizona, USA, to increase bighorn sheep (Ovis canadensis) population densities and to restore herds to suitable habitat throughout their historical range. Yet, translocation can also alter the underlying genetic diversity and spatial structure of managed wildlife species in beneficial or detrimental ways. To evaluate the long‐term effect of translocation actions on bighorn sheep, we characterized statewide genetic structure and diversity using microsatellite and mitochondrial DNA data in 16 indigenous and translocated (supplemented or reintroduced) Arizona populations sampled between 2005 and 2012. Populations that were recipients of translocated animals showed no reduction in genetic diversity with allelic richness and heterozygosity estimates equivalent to, and in some cases greater than, indigenous source populations. The indigenous population occupying the Silver Bell Mountains population displayed the lowest indices of genetic diversity but shared mitochondrial DNA haplotypes with the Mohawk Mountains, Sierra Pinta, and Cabeza Prieta populations, indicating past connectivity and potential opportunities for genetic management if warranted. Bayesian clustering on genetic similarity and genetic divergence estimates corroborated previous work differentiating Rocky Mountain bighorn sheep (O. c. canadensis) and 2 desert lineages corresponding with Nelson's (O. c. nelsoni) and Mexican desert bighorn sheep (O. c. mexicana). In northern Arizona, assignment tests confirmed the presence of 2 indigenous metapopulations of Nelson's desert bighorn sheep in the Black Mountains and Grand Canyon and indicated that gene flow from the Grand Canyon population has likely played a role in maintaining genetic diversity and mitigating founder effects among multiple translocated populations in the area. In southern Arizona, we detected genetic structure consistent with 2 metapopulations of Mexican desert bighorn sheep representing a departure from current management practices that consider this lineage to be a single genetic unit. Several lines of genetic evidence presented in this study suggest that the Bill Williams River area is the contemporary contact zone for the 2 desert lineages; however, the degree to which translocation has enhanced introgression is unknown. Despite relative isolation from other herds, the translocated Rocky Mountain bighorn sheep population in eastern Arizona had high levels of allelic richness and heterozygosity and a negative inbreeding coefficient, conceivably as a result of multiple translocation events from sources in Colorado and New Mexico, USA. Although translocation management has successfully contributed to the reestablishment of bighorn sheep populations in Arizona without diminishing genetic diversity, future translocation should proceed with caution to preserve the genetic integrity and potential local adaptation within the Nelson's and Mexican desert bighorn sheep metapopulations identified in this stu...

Selection of forage and habitats is driven by nutritional needs of individuals. Some species may sacrifice nutritional quality of forage for the mother in favor of safety of offspring (risk-averse strategy), immediately following parturition. We studied diet quality and forage selection by bighorn sheep before and following parturition to determine how nutritional demands associated with rearing offspring influenced forage acquisition. We used desert bighorn sheep, Ovis canadensis nelsoni, to investigate that potential tradeoff. We captured and radio-collared female bighorn sheep from 2016 to 2018. We used vaginal implant transmitters (VIT)s in pregnant females to identify parturition and to capture and radio-collar neonates to monitor survival of young. We collected fecal samples throughout the breeding season and throughout the year to understand diet quality and composition throughout those temporal periods. We determined diet quality and composition for pre-parturient females, females provisioning offspring, females that lost offspring, and non-pregnant individuals using fecal nitrogen and DNA metabarcoding analyses. Additionally, we compared the diet quality and composition of offspring and adult females during the spring, as well as summer and winter months. Our results indicated differences in diet quality between individuals provisioning offspring and those whose offspring had died. Females that were provisioning dependent young had lower quality diets than those that lost their offspring. Diet composition among those groups was also markedly different; females that had lost an offspring had a more diverse diet than did females with dependent young. Diet quality differed among seasons, wherein offspring and adult females had higher quality diets during the spring months, with decreasing quality as the year progressed. Diet diversity was similar across seasons, although spring months tended to be most diverse. Our results support tradeoffs associated with risk-averse strategies made by adult females associated with parturition. Nutritional quality of forage was linked to provisioning status, indicating that females were trading diet quality for safety of offspring, but those females whose offspring had died selected high quality forages. Those results help explain habitat selection observed in mountain ungulates around parturition and provide further insight into the evolutionary processes and adaptive significance exhibited by those specialized artiodactyls.