Journal of Wildlife Management最新文献

Since the passage of the Wild Free-Roaming Horses and Burros Act of 1971, federal agencies have been responsible for managing free-roaming equids in the United States. Over the last 20 years, management has been hampered by direct opposition from advocacy groups, budget limitations, and a decline in the public's willingness to adopt free-roaming horses (Equus caballus). As a result, free-roaming equid numbers have increased to >3 times the targeted goal of 26,785 (horses and burros [E. asinus] combined), the cumulative sum of the appropriate management levels (AML) for all 177 designated herd management areas (HMA) managed by the Bureau of Land Management. This increase is one of the causes of greater sage-grouse (Centrocercus urophasianus) population declines, owing to habitat alteration from free-roaming equids exacerbated by ongoing drought. To evaluate potential demographic mechanisms influencing these declines, we compiled survival data from 4 studies in central Wyoming, USA, including 995 adult female (first-year breeders or older) sage-grouse during the breeding season, 1,075 nests, 372 broods, and 136 juveniles (i.e., overwinter survival for fledged young), from 2008–2022. During this period, we also obtained population information for free-roaming horses from 9 HMAs used by individual grouse in our sample. Population estimates of free-roaming horses for these HMAs ranged from 59% to 7 times of the maximum appropriate management level (AML_max). Sage-grouse monitored outside of HMAs represented control populations and, because we assumed they were not exposed to populations of free-roaming horses, we set values of AML_max to zero for all grouse located outside of HMAs. To evaluate whether free-roaming horses were negatively affecting sage-grouse, we modeled daily survival of breeding age females, nest, broods, and juveniles. There was strong or moderate evidence that overabundant free-roaming horses negatively affected nest, brood, and juvenile survival. When horse abundance increased from AML_max to 3 times AML_max, survival was reduced 8.1%, 18.3%, 18.2%, and 18.2% for nests, early broods (≤20 days after hatch), late broods (>20 days to 35 days after hatch), and juveniles, respectively. These results indicate increasing free-roaming horse numbers affected vital rates for important life stages of sage-grouse, and that maintaining free-roaming horse numbers below AML_max would reduce negative effects to sage-grouse populations.

Golden eagles (Aquila chrysaetos) face many anthropogenic risks including illegal shooting, electrocution, collision with wind turbines and vehicles, and lead poisoning. Minimizing or offsetting eagle deaths resulting from human-caused sources is often viewed as an important management objective. Despite understanding the leading anthropogenic sources of eagle fatalities, existing scientific research supports few practical solutions to mitigate these causes of death. We implemented a non-lead ammunition distribution program in southeast Wyoming, USA, and evaluated its effectiveness as a compensatory mitigation action to offset incidental take (i.e., fatalities) of golden eagles at wind energy facilities. In 2020 and 2022, we distributed non-lead ammunition to 699 hunters with big-game tags specific to our >400,000-ha study area. These hunters harvested 296 pronghorn (Antilocapra americana), 14 deer (Odocoileus spp.), and 33 elk (Cervus canadensis) in the study area, which accounted for 6.9% and 6.5% of the harvest in these hunt units in 2020 and 2022, respectively. We used road surveys in 2020 to estimate a density of 0.036 (95% CI = 0.018–0.058) golden eagles/km² during the big game hunting season in our study area. Model output suggests that our non-lead ammunition distribution program offset the fatality of 3.84 (95% CI = 1.06–23.72) eagles over the course of these 2 hunting seasons. Our work illustrates the potential usefulness of non-lead ammunition distribution programs as an action to mitigate eagle fatalities caused by wind facilities or other anthropogenic causes of death.

Nature-based tourism nets roughly 8 billion annual travelers globally to all regions of Earth, with many visiting around 200,000 formally protected areas. Financially well-off tourists pay for playful activities and effects on wildlife are potentially large and relatively uncertain. Our commentary makes 3 points. First, variation in resource privileges and associated benefits characterizes not only humans but other species. Among animals, well-nurtured populations engage in more playful and leisurely activities than do those nutritionally impoverished. Privilege depends partially on birth sites, parents, and local conditions, but for humans recreation expands with monetary advantage. Second, nature-based tourism has 2 generalizable effects on wildlife, each involving degree of habituation. Among non-habituated populations, local site abandonment is frequent and modulated by seasonality, individuals' physiological states, and whether recreation is motorized or not. For habituated populations, tolerance emerges to increasing recreational exposure with some populations of species learning to rely on humans to shield as a buffer against possible predation. Third, desert bighorn sheep (Ovis canadensis nelsoni) offer a robust example of the issues surrounding the effects of tourism on wildlife because of the geographically complicated relationship between recreational pursuit and wildlife on public lands of the western United States. While protected for decades, females have failed to habituate to different forms of recreation at certain sites. The result has been flight or site abandonment. Biodiversity protection at numerous scales has made strong gains but is still needed where progress is stymied by income disparities, privilege, and increasing recreation ventures.

The Titicaca grebe (Rollandia microptera) is a poorly studied endangered species, only found in the Lake Titicaca watershed of Peru and Bolivia. Population surveys undertaken in the early twenty-first century suggested that the species had declined in number by >70%. We conducted a population survey of the grebe between March and August 2022 in Peru and Bolivia, using both maximum entropy and Bayesian occupancy models to estimate factors affecting habitat suitability for the grebe. We conducted surveys between March and August 2022 in Peru and Bolivia. Contrary to the International Union for Conservation of Nature (IUCN) population estimates of <1,000 individuals, there are likely tens of thousands of individual grebes. The population estimation was sensitive to the type of model used. Distance from shore and fishing intensity were the most significant factors influencing grebe populations. The Reserva Nacional del Titicaca, the only protected area in the lake, covers some of the most suitable Titicaca grebe habitat across its entire range. The population of the Titicaca grebe is significantly higher than previous estimates, but we do not recommend a change to its conservation status because of the lack of conservation efforts for this species, and the long-term risks associated with global warming and fisheries bycatch.

Outdoor recreational use is growing rapidly in the western United States, which increases the pressure on multiple-use public lands. Balancing recreational use with conservation goals requires considering the spatial and temporal intensity of recreational use and examining its effects on multiple species within an ecosystem. In 2019–2021, we assessed the relationship between recreational intensity and the abundance of a dominant prey species (Piute ground squirrel [Urocitellus mollis]), the abundance of avian and mammalian facultative scavengers that rely on ground squirrels, and the abundance and nesting success of ground-nesting birds at a national conservation area in southwestern Idaho, USA, where recreational shooting and off-highway vehicle use are the primary recreational activities. Recreational intensity varied across the study site. The abundance of ground squirrels was not related to recreational intensity. The abundance of common ravens (Corvus corax) and the abundance of American badgers (Taxidea taxus), 2 common facultative scavengers, were both positively associated with recreational intensity, while the abundance of other avian facultative scavengers was not related to recreational intensity. The abundance of horned larks (Eremophila alpestris) and nesting success of long-billed curlews (Numenius americanus), a more sensitive species, were negatively related to recreational intensity. Together, our results highlight the importance of considering variation in recreational intensity and the effect of recreation on multiple guilds within the ecosystem. An improved understanding of these relationships can be used with public land management to protect wildlife while providing opportunities for outdoor recreation.