Filters: Tags: population decline (X)5 results (16.8s)
Raven Observations near Greater Sage-Grouse Nests in the Great Basin and Bi-State Regions of the Western United States (2009 - 2019)
These tables serve as input data for hierarchical models investigating interactions between raven density and Greater Sage-grouse nest success. Observations were recorded over an 11 year time period, spanning from 2009 through 2019. The model is run in JAGS via R, the code is publicly available via the U.S. Geological Survey's GitLab (O'Neil et al. 2023). We recommend not making any changes or edits to the tables unless the user is experienced with hierarchical modeling. References: O'Neil, S.T., Coates, P.S., Webster, S.C., Brussee, B.E., Dettenmaier, S.J., Tull, J.C., Jackson, P.J., Casazza, M.L., and Espinosa, S.P., 2023, Code for a hierarchical model of raven densities linked with sage-grouse nest survival...
Sea otter surveys from selected Western Aleutian Islands, Alaska and Bering Island, Russia between 1959-2015
The data table consists of a compilation of sea otter survey results from Bering Island, Russia and select Western Aleutian Islands conducted between 1959 and 2015. The counts were reduced to sea otters per kilometer of coastline for temporal comparability. A correction factor of 3.6 was applied to aerial survey totals to yield results comparable to skiff based surveys. The data table provides the island, year, mode (aerial, skiff, or ground), and shore length covered in each survey. Counts of independent otters and pups are provided if available. Total otters counted or calculated with the correction factor and the calculated linear density are also provided.
Rasters representing median raven density estimates, calculated from approximately 28,000 raven point count surveys conducted between 2009 and 2019. Estimates were the result of a Bayesian hierarchical distance sampling model, using environmental covariates on detection and abundance.
Data to Support Hierarchical Models and Decision Support Maps to Guide Management of Subsidized Avian Predator Densities
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...
Estimates of Raven Impacts on Greater Sage-Grouse Nest Survival Delineated by Field Site in California, Nevada, and Idaho (2009 - 2019)
These rasters are the result of calculating the difference in Greater Sage-grouse nest survival after a simulated reduction of raven density to 0.1 ravens per square kilometer. The difference in nest survival represents spatial variation in potential to improve nest survival by reducing raven impacts. The extent of each individual raster is the extent of the field site at which sage-grouse nest observations were recorded.