In the Great Basin, invasion by cheatgrass has altered landscape structure and ecosystem function. By usurping resources and modifying habitat, cheatgrass has caused dramatic reductions in plant and wildlife abundance and diversity. Though this pattern of biodiversity loss is clear, the mechanisms and landscape scale implications remain unknown. There is little information on whether cheatgrass impacts reptile communities. We hypothesize that loss of shrub cover in cheatgrass dominated areas will leave fewer thermal microhabitats and temperature gradients for reptiles to thermoregulate. To test this, we developed operative temperature models based on Sceloporus occidentalis to deploy at paired sites (cheatgrass vs. native shrub habitat) in northwestern Nevada.  Cheatgrass dominated sites are, on average, significantly hotter than shrub sites. Reptiles in the Great Basin rely on shrub cover to avoid critically hot temperatures, the loss of such refuges may result in temperatures restrictive for normal activity. Cheatgrass habitat may be thermally unsuitable and represent habitat loss for reptiles. We have identified a plausible mechanism of biodiversity loss due to cheatgrass invasion: modified temperature regimes and loss of thermal microhabitats. Given that 10% of the Great Basin has converted to cheatgrass monocultures, we expect significant regional declines in reptile abundance, diversity and connectivity.

Abandoned mines shelter bats and other wildlife. However, mines are often threatened with closure for human safety and renewed mining in historic districts. Bat-compatible closures have been installed in thousands of mines across North America to prevent human entry but allow bat entry. As white-nose syndrome (WNS) progresses westward across the continent, protecting bat roosts can slow the spread via human transport of the deadly fungus that causes WNS. If mines are to be permanently destroyed in renewed mining operations, bats should be evicted at the appropriate season and replacement habitat should be installed with bat gates. The timing of surveys and methods used influence the detectability of seasonal bat use of a mine. Many bat species use several roosts throughout their annual cycle, as dictated by physiological and behavioral needs. When evaluating bat use of mines recommended for closure, the goals should be to identify the most important mine roosts and avoid installing incompatible closures that may cause roost abandonment. Not all types of mine closures are acceptable to all species of bats at all times of year, and suitability may depend on colony size as well as closure size and design. Some colonies do not accept corrugated culverts or even gates. After installing any bat-compatible closure, a monitoring program should be implemented to assess its effectiveness.

Desert bighorn sheep (Ovis canadensis nelsoni) occupy a diversity of desert ecosystems throughout the southwestern United States. Significant climatic differences among these desert ecosystems suggests the potential for adaptation to local conditions in this taxon. We tested for signatures of local adaption using 2b-RAD reduced representation genotyping in conjunction with high resolution climate data for 30 native populations of desert bighorn sheep (291 individuals) distributed throughout much of its North American range. Population differentiation and ecological association tests on 11,303 SNPs identified outlier loci with alleles private to the Great Basin of California and Nevada. Private allele frequencies were correlated with higher elevation and lower annual mean temperature; logistic regression, P < 0.001. Outlier loci mapped to a ~ 5 Mb sequence on chromosome 8 of the domestic sheep genome (Oar v3.0) encompassing the EPH receptor A7 gene and six other undescribed protein coding genes. Our data suggest the few remaining desert bighorn herds native to the Great Basin may represent a unique ecotype and should be managed accordingly. Understanding the range of adaptive genetic variation present within desert bighorn sheep may prove instrumental in predicting how this taxon might respond to global climate change.

 Environmental DNA (eDNA) detection techniques are gaining popularity as a means of surveying for rare and often cryptic amphibians. Land managers and regulatory agencies are beginning to request collection of these data as part of routine biological surveys for long-term monitoring, such as on hydroelectric relicensing projects. We present methods and results of an initial trial for one season of eDNA sampling efforts on stream reaches in the Plumas National Forest, targeting the Sierra Nevada yellow-legged frog (Rana sierrae), a federally endangered species. We utilized both visual encounter surveys and eDNA riverine sampling to infer species presence/absence on three high-gradient intermittent stream reaches. Results from eDNA sampling were consistent with lack of detections in two reaches that were surveyed visually. At a third site, the species was detected visually but not with eDNA in August, and with eDNA but not visual surveys in September. This highlights the importance of identifying optimal methods for eDNA sampling based on site-specific environmental conditions, as well as the current benefits of continued incorporation of traditional methods when making management recommendations that may affect amphibian habitat.

The endangered giant kangaroo rat (Dipodomys ingens, GKR) is a keystone species restricted to the San Joaquin Desert of California, whose range has been reduced to 3% of historical, largely due to habitat loss to irrigated agriculture. The main remaining populations of the GKR are divided into two distinct and fragmented populations 150 km apart: the northern GKR of the Ciervo-Panoche natural area and the southern GKR of the Carrizo Plain. To aid in conservation efforts we sought to understand the demographic history of the species, the historical relationship between the major remaining populations, and to determine how the genetic diversity of the species is partitioned across the range. We set out to achieve this by examining >275 GKR at two mitochondrial DNA regions (>800 bp) and 17 nuclear microsatellites. We estimated that the main populations of GKR split 774-5,600 years ago, prior to agricultural intensification during the 20th century. Within the northern Ciervo-Panoche area we resolved multiple distinct subpopulations, and identified the Tumey Hills as a major source population. Identification of geographically discrete populations of giant kangaroo rats and the relationships among them will aid in conservation decision making by management agencies.

It is well documented that bridges offer substantial amounts of roost habitat for millions of bats. Many bridges provide temporal and environmental stability, which makes them highly suitable for use by bats during seasonal periods of bat activity and in some cases also during winter. Bridges are usually large structures that can support large colonies, often with a variety of roost features and characteristics that make them attractive to multi-species assemblages. Bats that use bridges vary in size as well as preference of roost feature characteristics. The author provides design criteria, including bridge- and species-specific details, of successfully-occupied replacement, in-structure roost habitat, which he has developed and refined over many years for bridges in California. The author also discusses the iterative, cooperative processes involved in working with bridge engineers and architects to incorporate important biological requirements into construction plans and completed bridges.