Projecting current and future location, quality, and connectivity of habitat for breeding birds in the Great Basin

Abstract

We estimated the current location, quality, and connectivity of habitat for 50 species of breeding birds in four mountain ranges in the central Great Basin (Lander, Nye, and Eureka Counties, Nevada) and projected the future location, quality, and connectivity of habitat for these species given different scenarios of climate-induced land-cover change. In the United States, such models are relevant to federally mandated management of wild animals by state-level agencies. We sampled birds during the breeding seasons of 2001-2009 with fixed-radius point counts. For each species, we used boosted regression trees to model incidence (proportion of years a location was surveyed in which the species was present) as a function of topography and current land cover and climate. To assess model fit, we calculated the proportion of binomial deviance explained. We used cross-validation to estimate the predictive accuracy of the models. We applied the conservation planning program Zonation to identify locations where incidences of multiple species were maximized through time given current land cover and two scenarios of land-cover change, expansion of pinyon-juniper woodland into sagebrush shrubsteppe and contraction of riparian woodland. Models based on a set of 13 covariates derived from remotely sensed data had some predictive capacity for 41 of 50 species. Model outputs suggested substantial changes in amount of habitat for many species following projected expansion of pinyon-juniper woodland, but less pronounced changes following projected contraction of riparian woodland. Zonation analyses indicated that the spatial distribution of the highest-quality habitat for the avian assemblage was relatively consistent through time under both scenarios. Breeding birds in the Great Basin commonly are grouped in management plans on the basis of their general association with land-cover classes such as pinyon-juniper woodland, sagebrush shrubsteppe, and riparian woodland. However, even within these groups, the environmental attributes that explained a high proportion of variation in species' incidences and the projected responses to different scenarios of land-cover change varied considerably among species. © 2014 Fleishman et al.