A hierarchical occupancy model adapted from Royle & Dorazio (2008) and Rota et al. (2011) for use in R.

We combined approximately 28,000 raven point count surveys with data from more than 900 sage-grouse nests between 2009 and 2019 within the Great Basin, USA. We modeled variation in raven density using a Bayesian hierarchical distance sampling approach with environmental covariates on detection and abundance. Concurrently, we modeled sage-grouse nest survival using a hierarchical frailty model as a function of raven density as well as other environmental covariates that influence risk of failure. Raven density commonly exceeded more than 0.5 ravens per square kilometer and increased at low relative elevations with prevalent anthropogenic development and/or agriculture. Reduced sage-grouse nest survival was strongly associated with elevated raven density (e.g., more than 0.5 ravens per square kilometer) and varied with topographic ruggedness, shrub cover, and burned areas. For conservation application, we developed a spatially explicit planning tool that predicts nest survival under current and reduced raven numbers at local areas within the Great Basin to help direct management actions to locations where sage-grouse nests are at highest risk of failure. Our modeling framework can be generalized to multiple species where spatially registered abundance and demographic data are available.

Predictions of an anthropogenic influence on raven occurrence index intersected with sage-grouse concentration areas. The anthropogenic influence index indicates where resource subsidies are contributing the most to raven occurrence.

Predictions of an anthropogenic influence on raven occurrence index intersected with sage-grouse concentration areas. The anthropogenic influence index indicates where resource subsidies are contributing the most to raven occurrence.

Expanding human enterprise across remote environments impacts many wildlife species, including sage-grouse (Centrocercus urophasianus), an indicator species whose decline is at the center of national conservation strategies and land use policies. Anthropogenic resources provide subsidies for generalist predators, potentially leading to cascading effects on sensitive prey species at lower trophic levels. In semi-arid western ecosystems, common ravens (Corvus corax) are expanding in distribution and abundance, and may be negatively affecting sage-grouse reproductive success at broad spatial scales. Ravens are a common predator of sage-grouse nests, and potentially prey on chicks as well. This research aimed to address the growing demand for information about potential interactions between subsidized predators (i.e. ravens) and species they prey upon. More specifically, our objectives were to disentangle natural and anthropogenic influences on raven occurrence at a landscape scale, and provide spatially explicit models and scientific products to help inform decisions regarding the management of ravens and conservation of sage-grouse. Using Bayesian hierarchical occupancy models, we mapped the broad-scale occurrence of common ravens as a function of natural and anthropogenic landscape covariates using more than 15,000 point count surveys performed during 2007–2016 within the Great Basin region, USA. In addition, we provide spatially explicit model-predicted surfaces that integrate anthropogenic and natural effects on raven occurrence with underlying information about breeding sage-grouse concentration areas. This approach meets several objectives with respect to the conservation and management of sage-grouse and ravens. First, we established landscape-level patterns of predicted raven occurrence across the Great Basin region. Second, we determined associations between anthropogenic and natural features, and the broad-scale occurrence of ravens. Third, we identified regions where A) high predicted raven occurrence overlapped with breeding sage-grouse concentration areas, and B) areas where raven occurrence was strongly influenced by anthropogenic (vs. natural) variables overlapping with breeding sage-grouse concentration areas. This approach can guide management decisions where subsidized predators overlap sensitive prey habitats. For example, management applications could focus on reducing raven access to anthropogenic subsidies in areas where elevated raven occurrence coincides with breeding sage-grouse concentration areas and appears to be largely driven by anthropogenic factors, while prioritizing habitat improvements for sage-grouse elsewhere. Our approach is applicable to other species where widespread survey data are available. These data support the following publication: O’Neil, S.T., Coates, P.S., Brussee, B.E., Jackson, P.J., Howe, K.B., Moser, A.M., Foster, L.J., and Delehanty, D.J. 2018, Broad-scale occurrence of a subsidized avian predator: reducing impacts of ravens on sage-grouse and other sensitive prey. Journal of Applied Ecology

Expanding human enterprise across remote environments impacts many wildlife species, including sage-grouse (Centrocercus urophasianus), an indicator species whose decline is at the center of national conservation strategies and land use policies. Anthropogenic resources provide subsidies for generalist predators, potentially leading to cascading effects on sensitive prey species at lower trophic levels. In semi-arid western ecosystems, common ravens (Corvus corax) are expanding in distribution and abundance, and may be negatively affecting sage-grouse reproductive success at broad spatial scales. Ravens are a common predator of sage-grouse nests, and potentially prey on chicks as well. This research aimed to address the growing demand for information about potential interactions between subsidized predators (i.e. ravens) and species they prey upon. More specifically, our objectives were to disentangle natural and anthropogenic influences on raven occurrence at a landscape scale, and provide spatially explicit models and scientific products to help inform decisions regarding the management of ravens and conservation of sage-grouse. Using Bayesian hierarchical occupancy models, we mapped the broad-scale occurrence of common ravens as a function of natural and anthropogenic landscape covariates using more than 15,000 point count surveys performed during 2007–2016 within the Great Basin region, USA. In addition, we provide spatially explicit model-predicted surfaces that integrate anthropogenic and natural effects on raven occurrence with underlying information about breeding sage-grouse concentration areas. This approach meets several objectives with respect to the conservation and management of sage-grouse and ravens. First, we established landscape-level patterns of predicted raven occurrence across the Great Basin region. Second, we determined associations between anthropogenic and natural features, and the broad-scale occurrence of ravens. Third, we identified regions where A) high predicted raven occurrence overlapped with breeding sage-grouse concentration areas, and B) areas where raven occurrence was strongly influenced by anthropogenic (vs. natural) variables overlapping with breeding sage-grouse concentration areas. This approach can guide management decisions where subsidized predators overlap sensitive prey habitats. For example, management applications could focus on reducing raven access to anthropogenic subsidies in areas where elevated raven occurrence coincides with breeding sage-grouse concentration areas and appears to be largely driven by anthropogenic factors, while prioritizing habitat improvements for sage-grouse elsewhere. Our approach is applicable to other species where widespread survey data are available. These data support the following publication: O’Neil, S.T., Coates, P.S., Brussee, B.E., Jackson, P.J., Howe, K.B., Moser, A.M., Foster, L.J., and Delehanty, D.J. 2018, Broad-scale occurrence of a subsidized avian predator: reducing impacts of ravens on sage-grouse and other sensitive prey. Journal of Applied Ecology

Raven point counts were related to landscape covariates using Bayesian hierarchical occupancy models and the mean of the predicted posterior distribution for raven occurrence was used to visualize results.

Raven point counts were related to landscape covariates using Bayesian hierarchical occupancy models and the mean of the predicted posterior distribution for raven occurrence was used to visualize results.

This dataset presents four tabular data files that evaluate the effect of predator exclosures around piping plover (Charadrius melodus) nests affects plover nest, chick, within-season, and annual adult survival. During 2014-2016, this data was part of a designed experiment to examine nest (n = 418), chick (n = 453), and adult (n = 367) survival at alkaline wetlands of the Northern Great Plains. Alkaline wetlands were divided between treatment wetlands and control wetlands (no exclosures placed anywhere on wetland). Field crews aimed to place predator exclosures around half of all plover nests found resulting in three treatment types: uncaged nest on control wetland, uncaged nest on treatment wetland, and caged nest on treatment wetland. The nest survival dataset includes values used with the Shaffer logistic exposure model as well as the treatment of nest and wetland separately. The chick survival dataset includes a censored Cormack-Jolly-Seber encounter history based on when chicks were searched for and in addition to the experimental treatment, the region of the study area and the density of chicks at each wetland basin are included. Adult survival was examined over two time periods, during incubation (within season) and annually, resulting in two separate datasets, and took advantage of resightings of individuals outside the focal study area. The within season survival dataset includes a Barker model encounter history, region, experimental treatment, and a measure of habitat availability based on a climate index (standardized precipitation-evapotranspiration index). The annual adult survival dataset includes a Barker model encounter history and the time-varying experimental treatment.

Predictions of raven occurrence intersected with high impact areas for sage-grouse populations. The index highlights regions where elevated raven occurrence is likely to impact breeding sage-grouse