Functional attributes of ungulate migration: landscape features facilitate movement and access to forage.

Long-distance migration by terrestrial mammals is a phenomenon critical to the persistence of populations, but such migrations are declining globally because of over-harvest, habitat loss, and movement barriers. Increasingly, there is a need to improve existing routes, mitigate route segments affected by anthropogenic disturbance, and in some instances, determine whether alternative routes are available. Using a hypothesis-driven approach, we identified landscape features associated with the primary functional attributes, stopovers and movement corridors, of spring migratory routes for mule deer in two study areas using resource selection functions. Patterns of selection for landscape attributes of movement corridors and stopovers mostly were similar; however, landscape features associated with movement corridors aligned better with areas that facilitated movement, whereas selection of stopovers was consistent with sites offering early access to spring forage. For movement corridors, deer selected for dry sites, low elevation, and low anthropogenic disturbance. For stopovers, deer selected for dry sites, with consistently early green-up across years, south-southwesterly aspects, low elevation, and low anthropogenic disturbance. Stopovers and movement corridors of a migratory route presumably promote different functions, but for a terrestrial migrant, patterns of habitat selection indicate that the same general habitat attributes may facilitate both movement and foraging in spring. Our findings emphasize the roles of topographical wetness, vegetation phenology, and anthropogenic disturbance in shaping use of the landscape during migration for this large herbivore. Avoiding human disturbance and tracking ephemeral forage resources appear to be a consistent pattern during migration, which reinforces the notion that movement during migration has a nutritional underpinning and disturbance potentially alters the net benefits of migration.

Effects of Lead Exposure, Flock Behavior, and Management Actions on the Survival of California Condors (Gymnogyps californianus).

Translocation is an increasingly important tool for managing endangered species, but factors influencing the survival of translocated individuals are not well understood. Here we examine intrinsic and extrinsic drivers of survival for critically endangered California condors (Gymnogyps californianus) whose wild population recovery is reliant upon releases of captively bred stock. We used known fate models and information-theoretic methods to compare the ability of hypothesized covariates, most of which serve as proxies for lead exposure risk, to predict survival rates of condors in California. Our best supported model included the following predictors of survival: age of the recovery program, precipitation, proportion of days observed feeding on proffered carcasses, maximum blood lead concentration over the preceding 18 months, and time since release. We found that as flocks have increased in size and age, condors are increasingly likely to range more widely and less likely to be observed feeding on proffered food, and these "wilder" behaviors were associated with lower survival. After accounting for these behaviors, we found a positive survival trend, which we attribute to ongoing improvements in management. Our findings illustrate that the survival of translocated animals, such as highly social California condors, is influenced by behaviors that change through time.

Terrestrial Scavenging of Marine Mammals: Cross-Ecosystem Contaminant Transfer and Potential Risks to Endangered California Condors (Gymnogyps californianus).

The critically endangered California condor (Gymnogyps californianus) has relied intermittently on dead-stranded marine mammals since the Pleistocene, and this food source is considered important for their current recovery. However, contemporary marine mammals contain persistent organic pollutants that could threaten condor health. We used stable carbon and nitrogen isotope, contaminant, and behavioral data in coastal versus noncoastal condors to quantify contaminant transfer from marine mammals and created simulation models to predict the risk of reproductive impairment for condors from exposure to DDE (p,p'-DDE), a major metabolite of the chlorinated pesticide DDT. Coastal condors had higher whole blood isotope values and mean concentrations of contaminants associated with marine mammals, including mercury (whole blood), sum chlorinated pesticides (comprised of ∼95% DDE) (plasma), sum polychlorinated biphenyls (PCBs) (plasma), and sum polybrominated diphenyl ethers (PBDEs) (plasma), 12-100-fold greater than those of noncoastal condors. The mean plasma DDE concentration for coastal condors was 500 ± 670 (standard deviation) (n = 22) versus 24 ± 24 (standard deviation) (n = 8) ng/g of wet weight for noncoastal condors, and simulations predicted ∼40% of breeding-age coastal condors have DDE levels associated with eggshell thinning in other avian species. Our analyses demonstrate potentially harmful levels of marine contaminant transfer to California condors, which could hinder the recovery of this terrestrial species.

Modeling the distribution of migratory bird stopovers to inform landscape-scale siting of wind development.

Conservation of migratory birds requires understanding the distribution of and potential threats to their migratory habitats. However, although migratory birds are protected under international treaties, few maps have been available to represent migration at a landscape scale useful to target conservation efforts or inform the siting of wind energy developments that may affect migratory birds. To fill this gap, we developed models that predict where four groups of birds concentrate or stopover during their migration through the state of Wyoming, USA: raptors, wetland, riparian and sparse grassland birds. The models were based on existing literature and expert knowledge concerning bird migration behavior and ecology and validated using expert ratings and known occurrences. There was significant agreement between migratory occurrence data and migration models for all groups except raptors, and all models ranked well with experts. We measured the overlap between the migration concentration models and a predictive model of wind energy development to assess the potential exposure of migratory birds to wind development and illustrate the utility of migratory concentration models for landscape-scale planning. Wind development potential is high across 15% of Wyoming, and 73% of this high potential area intersects important migration concentration areas. From 5.2% to 18.8% of each group's important migration areas was represented within this high wind potential area, with the highest exposures for sparse grassland birds and the lowest for riparian birds. Our approach could be replicated elsewhere to fill critical data gaps and better inform conservation priorities and landscape-scale planning for migratory birds.

Measuring the effectiveness of conservation: a novel framework to quantify the benefits of sage-grouse conservation policy and easements in Wyoming.

Increasing energy and housing demands are impacting wildlife populations throughout western North America. Greater sage-grouse (Centrocercus urophasianus), a species known for its sensitivity to landscape-scale disturbance, inhabits the same low elevation sage-steppe in which much of this development is occurring. Wyoming has committed to maintain sage-grouse populations through conservation easements and policy changes that conserves high bird abundance "core" habitat and encourages development in less sensitive landscapes. In this study, we built new predictive models of oil and gas, wind, and residential development and applied build-out scenarios to simulate future development and measure the efficacy of conservation actions for maintaining sage-grouse populations. Our approach predicts sage-grouse population losses averted through conservation action and quantifies return on investment for different conservation strategies. We estimate that without conservation, sage-grouse populations in Wyoming will decrease under our long-term scenario by 14-29% (95% CI: 4-46%). However, a conservation strategy that includes the "core area" policy and $250 million in targeted easements could reduce these losses to 9-15% (95% CI: 3-32%), cutting anticipated losses by roughly half statewide and nearly two-thirds within sage-grouse core breeding areas. Core area policy is the single most important component, and targeted easements are complementary to the overall strategy. There is considerable uncertainty around the magnitude of our estimates; however, the relative benefit of different conservation scenarios remains comparable because potential biases and assumptions are consistently applied regardless of the strategy. There is early evidence based on a 40% reduction in leased hectares inside core areas that Wyoming policy is reducing potential for future fragmentation inside core areas. Our framework using build-out scenarios to anticipate species declines provides estimates that could be used by decision makers to determine if expected population losses warrant ESA listing.

Mapping oil and gas development potential in the US Intermountain West and estimating impacts to species.

BACKGROUND: Many studies have quantified the indirect effect of hydrocarbon-based economies on climate change and biodiversity, concluding that a significant proportion of species will be threatened with extinction. However, few studies have measured the direct effect of new energy production infrastructure on species persistence. METHODOLOGY/PRINCIPAL FINDINGS: We propose a systematic way to forecast patterns of future energy development and calculate impacts to species using spatially-explicit predictive modeling techniques to estimate oil and gas potential and create development build-out scenarios by seeding the landscape with oil and gas wells based on underlying potential. We illustrate our approach for the greater sage-grouse (Centrocercus urophasianus) in the western US and translate the build-out scenarios into estimated impacts on sage-grouse. We project that future oil and gas development will cause a 7-19 percent decline from 2007 sage-grouse lek population counts and impact 3.7 million ha of sagebrush shrublands and 1.1 million ha of grasslands in the study area. CONCLUSIONS/SIGNIFICANCE: Maps of where oil and gas development is anticipated in the US Intermountain West can be used by decision-makers intent on minimizing impacts to sage-grouse. This analysis also provides a general framework for using predictive models and build-out scenarios to anticipate impacts to species. These predictive models and build-out scenarios allow tradeoffs to be considered between species conservation and energy development prior to implementation.