An analysis of displacement from wind turbines in a wintering grassland bird community

Abstract

Wind energy development is rapidly increasing within breeding and wintering ranges of many grassland birds in North America. Despite recognized environmental benefits of such development, wind farms have the potential to negatively impact bird communities. Using an area-search method, we surveyed grassland birds within a matrix of pastures, hay fields, and agricultural lands at a wind facility in north-central Texas during the winters of 2009/10 and 2010/11. We used binary logistic regression to examine the effect of distance from wind turbines on plot occupancy for species that did not show significant habitat associations. In contrast, for species with significant habitat associations, we used a two-step process to test for displacement. First, we identified suitable plots using a niche modeling approach in Maxent. Second, we used binary logistic regression to examine whether distance to turbine influenced the occupancy of those plots. Sprague’s Pipit Anthus spragueii, Savannah Sparrow Passerculus sandwichensis, and meadowlarks Sturnella sp. showed no evidence for displacement. In contrast, the Le Conte’s Sparrow Ammodramus leconteii, was significantly more likely to occupy suitable plots as distance from the nearest turbine increased. Mean plot occupancy for the Le Conte’s Sparrow was more than four times lower in plots 400 m away. Our study highlights the need to investigate displacement at the level of individual species. Our data also suggest that species dependent on cryptic predator evasion strategies may be displaced from wind turbines and this idea warrants further investigation.