Influence of prescribed burning on bird abundance and species assemblage in a semiarid great plains grassland

Authors: A.M. Long, W.E. Jensen, R.S. Matlack

Encroachment of woody plants is widespread in semiarid grasslands of the southwestern United States. Wildlife responses to shrub removal techniques in the region are relatively unknown. In 2008 and 2009, we examined avian responses to prescribed burning of ungrazed shortgrass prairie within a study area (4811 ha) near Amarillo, Texas, that is heavily encroached by honey mesquite (Prosopis glandulosa) and cholla (Opuntia spp.). Specifically, we compared relative abundance, species richness, and species diversity of breeding birds across large, spatially replicated experimental plots burned every 2 or 4 years since 2002 and unburned controls. We found no significant differences in the mean relative abundance of most species across the treatments. However, Northern Bobwhite (Colinus virginianus), Cassin’s Sparrow (Peucaea cassinii), and Brown-headed Cowbird (Molothrus ater) were more abundant in less frequently burned plots and unburned controls. We found no differences in species richness or diversity across the treatments. Limited variation in avian responses across the treatments likely reflects the uniform pattern of vegetation structure we found across the plots, despite repeated application of prescribed fire at 2- and 4-year intervals over a 7-year period. Differences in bird species assemblages among the burn treatments might be more prominent in future years as prescribed burning continues.