Minimal bias in surveys of grassland birds from roadsides

ABSTRACT Edges, including roads, can have unintended deleterious impacts on wildlife. However, roads also present opportunities for replicable, and spatially and temporally consistent, wildlife monitoring. Assessing sources of variability associated with roadside-based surveys could improve the accuracy and extend the inferences of surveys, thus strengthening their applicability to management. We assessed roadside effects on abundance (λ) and detection probability (p) of high-priority grassland and shrubland songbirds in western Kentucky and Tennessee, USA. We delineated transects 300 m apart perpendicular to secondary roads and, along each transect, positioned point counts at 0 m, 300 m, and 600 m off the road. We surveyed 8 species: Northern Bobwhite (Colinus virginianus), Bell's Vireo (Vireo bellii), Prairie Warbler (Setophaga discolor), Field Sparrow (Spizella pusilla), Grasshopper Sparrow (Ammodramus savannarum), Henslow's Sparrow (Ammodramus henslowii), Dickcissel (Spiza americana), and Eastern Mead...