The Nevada Department of Wildlife (NDOW) is the state agency responsible for the restoration and management of fish and wildlife resources, and the promotion of boating safety on Nevada’s waters. NDOW has responsibility for the wildlife resources and enforcement of the wildlife and boating safety laws on 109,894 square miles (284,620 km2) of land, 667 square miles (1,730 km2) of water and 529 streams that flow 2,750 miles (4,430 km). NDOW's eleven state-owned wildlife management areas provide approximately 117,000 acres (47,000 ha) of wildlife habitat.
Aim: Population ecologists often focus on changes in the distribution and abundance of wildlife species, which are useful for trend analyses and status assessments. However, rarely are these responses evaluated simultaneously for a single species, despite their unique contributions to fully assess a species' viability. For example, focusing solely on total abundance can mask important losses in overall distribution within a metapopulation structure that may contribute to long-term population instability that results from the extirpation of small peripheral populations. Location: Bi-State region of Nevada and California, USA. Methods: We simultaneously evaluated changes in population abundance and distribution for greater sage-grouse (hereafter sage-grouse; Centrocercus urophasianus) within the Bi-State Distinct Population Segment (DPS), a genetically distinct and isolated population straddling the border of Nevada and California. We combined population counts, demographic data, and information on space use from marked individuals to evaluate changes in population distribution and abundance over three time periods that corresponded to the three most recent population nadirs (1995-2019, 2002-2019 and 2008-2019). Results: The Bi-State DPS exhibited evidence of similar to 1.2%-2.5% declines annually, over the short/medium-term (1995-2019; (lambda) over cap = 0.987, 95% CRI: 0.970-0.999), short-term (2002-2019; (lambda) over cap = 0.975, 95% CRI: 0.963-0.985) and recent-term (2008-2019; (lambda) over cap = 0.988, 95% CRI: 0.973-1.001). Since 1995, the spatial distribution of sage-grouse abundance in the Bi-State DPS shifted amongst subpopulations, with peripheral subpopulations suffering the largest declines. Main Conclusions: Gains in abundance and distribution amongst expanding subpopulations did not offset losses in the remaining subpopulations, with a net loss in occupied distribution of 156 km(2) since 1995. Reductions in spatial distribution could have implications for metapopulation persistence as peripheral populations become more vulnerable to stochastic events, which would not have been apparent from the evaluation of overall metapopulation abundance on its own.
Introduction Desert fishes are vulnerable to anthropogenic environmental alterations that degrade habitat and reduce water availability, but these same fishes benefit from restoration actions that reverse the causes of decline. Ash Meadows speckled dace (Rhinichthys osculus nevadensis) is a federally endangered minnow endemic to the Mojave Desert at Ash Meadows National Wildlife Refuge, Nevada, United States and is considered in need of conservation because of anthropogenic alterations to habitats they occupy.Objectives This study aims to establish quantitative associations between dace populations and environmental gradients that exist at Ash Meadows National Wildlife Refuge to guide restoration and management activities.Methods We fit an open-population generalized N-mixture model using environmental and repeated count data collected across four seasons to assess environmental covariates for abundance, detection, and apparent survival of Ash Meadows speckled dace. We also used total length data to analyze age structure and make inferences on recruitment and movement.Results We found that dace abundance was highest in habitats with deeper water and denser canopy cover; detection was greatest in habitats with open canopies and when surveys were conducted earlier in the day and used longer trap soak times; and apparent survival was highest at locations with denser canopy cover. We also found evidence of recruitment and recolonization in restored habitats across the refuge.Conclusions The tools and framework we apply here are applicable to other freshwater ecosystems afflicted by anthropogenic alterations and where restoration decisions require abundance-based information for organisms in need of conservation.
Escalating wildfire frequency and severity are altering wildland habitats worldwide. Yet investigations into fire impacts on wildlife habitat rarely extend to the macroecological scales relevant to species conservation and global change processes. We evaluate the effects of wildfire on habitat quality and selection by large mammals spanning three trophic levels in the Western United States. We analyze 12 years of GPS telemetry data for 2966 mule deer Odocoileus hemionus , 52 black bears Ursus americanus , and 74 cougars Puma concolor across Utah and Nevada, USA. Over 800 areas burned between 1990–2022 overlapped with the home ranges of 1892 animals, resulting in almost 23 000 km 2 of burned habitat and representing 12.8% of the total home range area for animals in our sample. Habitat suitability models for 664 mule deer, 14 black bears and 11 cougars indicated that burns improved summer home range quality for mule deer and black bears by 7% and 14%, respectively, highlighting the benefits of fires for nutrient cycling, understory herbaceous growth, and resultant caloric value for animal nutrition. When making fine‐scale movement decisions, however, mule deer avoided burned habitats, and all three species generally avoided high‐severity burns for up to 30 years post‐fire. Thus, the effects of burns on wildlife habitat selection appear to be dependent on spatial scale. Given projected increases in large, severe fires, our results suggest potential reductions in beneficial habitat for wildlife in the long term. However, our results also suggest that prescribed burns, because of their smaller spatial footprints and lower severity relative to wildfires, can benefit wildlife habitat quality through improvements in forage, cover, and other vegetation characteristics. Therefore, managing for low‐severity burns and limiting large, severe wildfires, e.g. via prescribed burns or fire control policies, could positively impact the habitat quality of these three common species and, therefore, the economic and ecosystem services they provide.
Animal-borne global positioning system (GPS) technology is advancing rapidly, providing new opportunities to study animal ecology and improve livestock management. Evaluation of emerging GPS technologies is needed, particularly those incorporating autonomous solar charging and satellite, cellular, and Long-Range Wide-Area Network (LoRaWAN) data transmission. We quantified and compared the performance of GPS neck collars and solar-powered GPS ear tags using stationary trials conducted under varying canopy cover conditions. Using a crossover design, we evaluated fix acquisition probability (Pacq), horizontal error (HE), circular error probable (CEP), and, when applicable, battery longevity for 10 GPS devices (7 collars and 3 ear tags) produced by 9 manufacturers. GPS performance was generally consistent across manufacturers and device types and showed limited sensitivity to canopy cover. Devices using LoRaWAN maintained high Pacq (0.92–0.99) across canopy conditions, though HE (2.94–19.70 m) and 95% CEP (7.07–77.83 m) varied substantially among devices. Track Tag and 701x ear tags exhibited high Pacq, low HE and CEP, and sustained functionality throughout the study, indicating potential for wildlife and livestock monitoring. A minimum of 84 locations was sufficient for centroid variation to reliably represent HE. Horizontal error was centered on a device-specific centroid rather than the true location, resulting in systematic bias ranging from 0.96 to 3.50 m, except for one device (11.52 m). Overall, GPS ear tags achieved performance metrics comparable to traditional collars. These results can inform technology selection, though extrapolation beyond stationary conditions should be made cautiously, as GPS performance is often optimized under static deployments.
ABSTRACT Aim Body size can influence nearly every aspect of organismal ecology, but drivers of intraspecific variation in body size are often poorly understood. We aimed to assess three hypotheses as potential explanations for intraspecific body size patterns in a desert ectotherm: that body size is driven by (i) potential foraging opportunities related to thermal constraints on activity; (ii) proxies for the abundance of resources (precipitation, primary productivity); and (iii) within and across year variability of resource availability. Location Southwestern United States, Northwestern Mexico. Methods We use a long‐lived lizard, Heloderma suspectum , to explore how environmental gradients inform body size patterns across a species range. We compile a dataset of measurements from 674 adult individuals spanning the entire species range and model body size as a function of 15 a priori selected environmental and mechanistic variables. Results We found body size was primarily influenced by spatial gradients in across‐year precipitation variability (+), within‐year resource seasonality (+), and within‐year average annual air temperature (−). Main Conclusions Our results suggest that within and among‐year patterns of resource availability are stronger drivers of body size than annual resource availability in the environment. Large body size may provide greater capacity for accumulating energy reserves, a potentially adaptive trait in environments where access to resources may be inconsistent across years and where resources may come in seasonal pulses.
