Ungulate migrations are assumed to stem from learning and cultural transmission of information regarding seasonal distribution of forage, but this hypothesis has not been tested empirically. We compared the migratory propensities of bighorn sheep and moose translocated into novel habitats with those of historical populations that had persisted for hundreds of years. Whereas individuals from historical populations were largely migratory, translocated individuals initially were not. After multiple decades, however, translocated populations gained knowledge about surfing green waves of forage (tracking plant phenology) and increased their propensity to migrate. Our findings indicate that learning and cultural transmission are the primary mechanisms by which ungulate migrations evolve. Loss of migration will therefore expunge generations of knowledge about the locations of high-quality forage and likely suppress population abundance.

Abstract. Mountain goats (Oreamnos americanus) are among the least studied North American ungulates.Aided by successful translocations from the early to mid-1900s, introduced populations have greatly expanded within non-native ranges, yet there remains a paucity of empirical studies concerning their habitat requirements and potential distributions. The lack of studies presents a formidable challenge to managers tasked with monitoring mountain goat expansion and mitigating for any potential negative impacts posed to native species and communities. We constructed summer and winter resource selection models using GPS data collected during 2011-2014 from 18 (14 female and four male) mountain goats in the Snake River Range of the southwest Greater Yellowstone Area. We used generalized linear mixed models and evaluated landscape and environmental covariates at multiple spatial grains (i.e., neighborhood analyses within 30-, 100-, 500-, and 1000-m buffers) within four related suites. The multi-grain resource selection function greatly improved model fit, indicating that mountain goat resource selection was grain dependent in both seasons. In summer, mountain goats largely selected rugged and steep areas at high elevations and avoided high solar radiation, canopy cover, and time-integrated normalized difference vegetation index (NDVI). In winter, mountain goats selected lower elevations characterized by steep and rugged slopes on warm aspects and avoided areas with high canopy cover, NDVI amplitude, and snow water equivalent. Slope was the dominant predictor of habitat use in both seasons, although mountain goats selected for steeper slopes in winter than in summer. Regional extrapolations depicted suitable mountain goat habitat in the Snake River, Teton, Gros Ventre, Wyoming, and Salt Ranges centered around steep and rugged areas. Winter range was generally characterized by the steepest slopes within a more broadly distributed and generally less steep summer range. Further research should examine the spatial and temporal overlap with native populations to further our understanding of resource selection dynamics and the potential for introduced mountain goats to alter intraguild behavioral processes of sympatric species, namely the Rocky Mountain bighorn sheep (Ovis canadensis canadensis).

Migration evolved as a behavior to enhance fitness through exploiting spatially and temporally variable resources and avoiding predation or other threats. Globally, landscape alterations have resulted in declines to migratory populations across taxa. Given the long time periods over which migrations evolved in native systems, it is unlikely that restored populations embody the same migratory complexity that existed before population reductions or regional extirpation. We used GPS location data collected from 209 female bighorn sheep ( Ovis canadensis ) to characterize population and individual migration patterns along elevation and geographic continuums for 18 populations of bighorn sheep with different management histories (i.e., restored, augmented, and native) across the western United States. Individuals with resident behaviors were present in all management histories. Elevational migrations were the most common population‐level migratory behavior. There were notable differences in the degree of individual variation within a population across the three management histories. Relative to native populations, restored and augmented populations had less variation among individuals with respect to elevation and geographic migration distances. Differences in migratory behavior were most pronounced for geographic distances, where the majority of native populations had a range of variation that was 2–4 times greater than restored or augmented populations. Synthesis and applications . Migrations within native populations include a variety of patterns that translocation efforts have not been able to fully recreate within restored and augmented populations. Theoretical and empirical research has highlighted the benefits of migratory diversity in promoting resilience and population stability. Limited migratory diversity may serve as an additional factor limiting demographic performance and range expansion. We suggest preserving native systems with intact migratory portfolios and a more nuanced approach to restoration and augmentation in which source populations are identified based on a suite of criteria that includes matching migratory patterns of source populations with local landscape attributes.

Population growth and range expansion of nonnative species can potentially disrupt ecosystem function or add conservation value to an area, and evaluation of possible impacts can be a challenge for managers. Nonnative populations of mountain goats (Oreamnos americanus) are present in the Greater Yellowstone Area (GYA) in the U.S. states of Idaho, Montana, and Wyoming because of historical introduction events, but their population trend and range have not been assessed across the area. We used 6,701 location records from 1947 to 2015 to map mountain goat distribution and evaluate, in a descriptive manner, range overlap with native bighorn sheep (Ovis canadensis). We analyzed 136 survey counts using the Exponential Growth State-Space model to estimate population trends and abundance. Mountain goats dispersed 50-85 km from introduction sites to occupy all mountain ranges in the northern GYA and 30-40 km to occupy new areas in the southern GYA. Mountain goat numbers increased in nearly all count units, with the strongest growth rates estimated in areas more recently colonized. Using moderate detection probability (0.70), we estimated approximately 2,355 mountain goats in the GYA. Although not tested in our analysis, the gradual range expansion and population growth rates were consistent with density-dependent processes observed in other introduced large herbivores and demonstrate that mountain goats can successfully disperse over unsuitable locales to colonize new areas. Therefore, we expect mountain goat populations will continue to expand into unoccupied mountain ranges that contain significant numbers of bighorn sheep unless specific management actions are implemented to address their population growth. Ó

Bighorn sheep (Ovis canadensis) populations in the western United States have undergone widespread declines and extirpations since the late nineteenth century as a consequence of introduced diseases, competition with livestock, and unregulated hunting. Washington, Idaho, USA, and British Columbia, Canada were historically thought to be occupied by 2 bighorn lineages or subspecies: Rocky Mountain (O. c. canadensis) and California (O. c. californiana). The putative California lineage was completely extirpated in the United States, and reintroductions to reestablish populations were sourced directly or indirectly from a single region in southern British Columbia. Restoration efforts have attempted to maintain the diversity and divergence of these 2 lineages, sometimes referred to as subspecies although taxonomic classifications have changed over time. In this study we describe genetic variation in a subset of native and reintroduced herds of California and Rocky Mountain bighorn sheep. We examined genetic diversity and divergence between bighorn sheep herds using 15 microsatellite loci, including 4 loci linked to genes involved in immune function. We analyzed 504 samples from reintroduced herds in Washington (n = 10 California herds, n = 4 Rocky Mountain herds) and Idaho (n = 5 California), and source herds in Oregon (n = 1 Rocky Mountain) and British Columbia (n = 5 California, 1 Rocky Mountain). Genetic structure reflected known reintroduction history, and geographic proximity also was associated with decreased genetic divergence. Herds in Washington and Idaho sourced from California bighorn sheep were less genetically diverse than those sourced from Rocky Mountain herds. Also, levels of relatedness within and across California herds were higher than in Rocky Mountain herds and similar to what would be expected for full and half siblings. Lower diversity and higher relatedness among California herds is a concern for long-term fitness and likely related to past population bottlenecks, fewer source populations, and management history, such as entirely sourcing California herds from British Columbia. Genetic divergence of neutral loci between California and Rocky Mountain herds was greater than that of adaptive loci, potentially indicating that balancing selection has maintained similar genetic diversity across lineages in loci associated with immune and other adaptive functions. Thus, we recommend future reintroductions and augmentations should continue to use source populations from the appropriate California or Rocky Mountain lineage to avoid potential outbreeding depression and maintain possible adaptive differences. This could be accomplished by obtaining sheep from ≥1 source within the genetic lineage, while avoiding sourcing from admixed herds. Future work encompassing a broader geographic sampling of populations and a greater portion of the genome is necessary to better evaluate the degree to which contemporary divergence between lineages is associated with recent founder effects and genetic isolation or evol...