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The responses of individual species to environmental changes can be manifested at multiple levels that range from individual-level (i.e., behavioral responses) to population-level (i.e., demographic) impacts. Major environmental changes that ultimately result in population level impacts are often first detected as individual-level responses. For example, herbivores respond to limited forage availability during drought periods by increasing the duration of foraging periods and expanding home range areas to compensate for the reduction in forage. However, if the individual-level responses are not sufficient to compensate for reduced forage availability, reduced survival and reproductive rates may result. We studied...
Abstract (from http://www.esajournals.org/doi/abs/10.1890/ES15-00266.1): Climate often drives ungulate population dynamics, and as climates change, some areas may become unsuitable for species persistence. Unraveling the relationships between climate and population dynamics, and projecting them across time, advances ecological understanding that informs and steers sustainable conservation for species. Using pronghorn ( Antilocapra americana) as an ecological model, we used a Bayesian approach to analyze long-term population, precipitation, and temperature data from 18 populations in the southwestern United States. We determined which long-term (12 and 24 months) or short-term (gestation trimester and lactation period)...
The responses of individual species to environmental changes can be manifested at multiple levels that range from individual-level (i.e., behavioral responses) to population-level (i.e., demographic) impacts. Major environmental changes that ultimately result in population level impacts are often first detected as individual-level responses. For example, herbivores respond to limited forage availability during drought periods by increasing the duration of foraging periods and expanding home range areas to compensate for the reduction in forage. However, if the individual-level responses are not sufficient to compensate for reduced forage availability, reduced survival and reproductive rates may result. We studied...
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Species that inhabit the arid Southwest are adapted to living in hot, dry environments. Yet the increasing frequency and severity of drought in the region may create conditions that even these hardy species can’t survive. This project examined the impacts of drought in the southwestern U.S. on four of the region’s iconic species: desert bighorn sheep, American pronghorn, scaled quail, and Rio Grande cutthroat trout. Grasping the impacts of drought on fish and wildlife is critical for management planning in the Southwest, as climate models project warmer, drier conditions for the region in the future. Species are known to respond to environmental changes such as drought in different ways. Often, before changes...
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Feral burros (Equus asinus) and horses (E. ferus caballus) inhabiting public land in the western United States are intended to be managed at population levels established to promote a thriving, natural ecological balance. Like many large ungulate populations, management agencies employ aerial surveys to obtain estimates of horse and burro population sizes. Double-observer sightability (MDS) models perform well for estimating feral horse abundances, yet the effectiveness of these models for use in burro populations is less understood and may be different due to the smaller size, stoic behavior, and cryptic pelage of burros. These models help minimize detection bias, yet bias can be further reduced with models that...
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This is the data archive for the publication Ungulate Migrations of the Western United States, Volume 4 and includes the collection of GIS map files that are mapped and described in the report. These map files are meant to provide a common spatial representation of the mapped migrations and seasonal ranges. This data release provides the means for ungulate migrations to be mapped and planned for across a wide variety of landscapes where they occur. Due to data sharing constraints of participating agencies, not all the files that underlie the mapped migrations included in the report have been released. Data in this archive can be downloaded two ways. To download by individual herd/range, clicking on child item pages...
Natural selection may result in local adaptation to different environmental conditions across the range of a species. Understanding local adaptation, in turn, informs management decisions such as translocation to restore locally-extinct populations. We used a landscape genomics approach to detect genetic signatures of selection related to climatic variation among desert bighorn sheep populations across their indigenous range in the western United States. This approach allowed us to investigate broad patterns of both neutral and adaptive genetic variation across very different environments. Analyses suggested that ancestry and isolation by distance were the most significant forces driving genetic variation in desert...
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Natural selection may result in local adaptation to different environmental conditions across the range of a species. Understanding local adaptation, in turn, informs management decisions such as translocation to restore locally-extinct populations. We used a landscape genomics approach to detect genetic signatures of selection related to climatic variation among desert bighorn sheep populations across their indigenous range in the western United States. This approach allowed us to investigate broad patterns of both neutral and adaptive genetic variation across very different environments. Analyses suggested that ancestry and isolation by distance were the most significant forces driving genetic variation in desert...
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Microsatellite genotypes for American black bears collected by Gould et al. 2002 and used to assess the genetic structure of American black bear populations in the American Southwest and northern Mexico. Genotypes are for Ursus americanus individuals.
The responses of individual species to environmental changes can be manifested at multiple levels that range from individual-level (i.e., behavioral responses) to population-level (i.e., demographic) impacts. Major environmental changes that ultimately result in population level impacts are often first detected as individual-level responses. For example, herbivores respond to limited forage availability during drought periods by increasing the duration of foraging periods and expanding home range areas to compensate for the reduction in forage. However, if the individual-level responses are not sufficient to compensate for reduced forage availability, reduced survival and reproductive rates may result. We studied...
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Natural selection may result in local adaptation to different environmental conditions across the range of a species. Understanding local adaptation, in turn, informs management decisions such as translocation to restore locally-extinct populations. We used a landscape genomics approach to detect genetic signatures of selection related to climatic variation among desert bighorn sheep populations across their indigenous range in the western United States. This approach allowed us to investigate broad patterns of both neutral and adaptive genetic variation across very different environments. Analyses suggested that ancestry and isolation by distance were the most significant forces driving genetic variation in desert...
Abstract (from http://onlinelibrary.wiley.com/doi/10.1111/oik.04282/abstract): Nutritional ecology forms the interface between environmental variability and large herbivore behaviour, life history characteristics, and population dynamics. Forage conditions in arid and semi-arid regions are driven by unpredictable spatial and temporal patterns in rainfall. Diet selection by herbivores should be directed towards overcoming the most pressing nutritional limitation (i.e. energy, protein [nitrogen, N], moisture) within the constraints imposed by temporal and spatial variability in forage conditions. We investigated the influence of precipitation-induced shifts in forage nutritional quality and subsequent large herbivore...
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The antelope-like pronghorn is the fastest land animal in North America and has the longest land migration in the continental U.S—in fact, the species has been dubbed “the true marathoners of the American West”. While pronghorns are numerous in parts of their range, such as Wyoming and northern Colorado, they are endangered in others, such as the Sonoran Desert. In the arid Southwest, pronghorn populations have been declining since the 1980s—and it’s thought that drought is partially to blame. Average temperatures in the Southwest have increased 1.6°C since 1901, and the area affected by drought from 2001-2010 was the second largest observed since 1901. Drought conditions have reduced the availability of vegetation,...
The responses of individual species to environmental changes can be manifested at multiple levels that range from individual-level (i.e., behavioral responses) to population-level (i.e., demographic) impacts. Major environmental changes that ultimately result in population level impacts are often first detected as individual-level responses. For example, herbivores respond to limited forage availability during drought periods by increasing the duration of foraging periods and expanding home range areas to compensate for the reduction in forage. However, if the individual-level responses are not sufficient to compensate for reduced forage availability, reduced survival and reproductive rates may result. We studied...
Natural selection may result in local adaptation to different environmental conditions across the range of a species. Understanding local adaptation, in turn, informs management decisions such as translocation to restore locally-extinct populations. We used a landscape genomics approach to detect genetic signatures of selection related to climatic variation among desert bighorn sheep populations across their indigenous range in the western United States. This approach allowed us to investigate broad patterns of both neutral and adaptive genetic variation across very different environments. Analyses suggested that ancestry and isolation by distance were the most significant forces driving genetic variation in desert...
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Native to the southwestern U.S. and northwestern Mexico, the desert bighorn sheep is known for its ability to adapt to harsh, arid environments. However, this does not mean the species is immune to the effects of drought. In fact, the fragmented and isolated distribution of the desert mountain ranges that they inhabit means that they can’t follow distant rain storms without traversing broad valleys at significant risk to mortality. This study examined the effects of a 2002 drought on desert bighorn sheep in the Cabeza Prieta National Wildlife Refuge in southwestern Arizona. Specifically, researchers explored how the drought may have affected habitat selection, behavior, and diet of the sheep. For example, when...
Abstract (from Ecosphere): When animals select areas to occupy, decisions involve trade‐offs between the fitness benefits of obtaining critical resources and minimizing costs of biotic and abiotic factors that constrain their use. These processes can be more dynamic and complex for species inhabiting desert environments, where highly variable spatial and temporal distribution of precipitation can create high intra‐ and inter‐annual variability in forage conditions and water availability, and thermal constraints can differ significantly among seasons and diel periods. We examined resource selection in desert bighorn sheep (Ovis canadensis mexicana) in Cabeza Prieta National Wildlife Refuge, Arizona, USA, at multiple...
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    map background search result map search result map The Impacts of Drought on Fish and Wildlife in the Southwestern U.S. The Effects of Drought on Desert Bighorn Sheep The Effects of Drought on Southwestern Pronghorns Evaluating Adaptive Capacity of Desert Bighorn Sheep to Climate Change: Identifying Genetic to Climate Adaptations in Native and Reintroduced Populations-SNP Matrix Evaluating Adaptive Capacity of Desert Bighorn Sheep to Climate Change: Identifying Genetic to Climate Adaptations in Native and Reintroduced Populations-Major Allele Frequency by Population Detections of burros from helicopter aerial surveys in the southwestern US, 2016-2018 Genetic structure of American black bear populations in the American Southwest and northern Mexico, 1994-2014 Ungulate Migrations of the Western United States, Volume 4 The Effects of Drought on Desert Bighorn Sheep Evaluating Adaptive Capacity of Desert Bighorn Sheep to Climate Change: Identifying Genetic to Climate Adaptations in Native and Reintroduced Populations-SNP Matrix Evaluating Adaptive Capacity of Desert Bighorn Sheep to Climate Change: Identifying Genetic to Climate Adaptations in Native and Reintroduced Populations-Major Allele Frequency by Population Genetic structure of American black bear populations in the American Southwest and northern Mexico, 1994-2014 Detections of burros from helicopter aerial surveys in the southwestern US, 2016-2018 The Impacts of Drought on Fish and Wildlife in the Southwestern U.S. The Effects of Drought on Southwestern Pronghorns Ungulate Migrations of the Western United States, Volume 4