Trends in grassland bird abundance following prescribed burning in southern Arizona

Abstract

I examined trends in relative abundance and species richness of breeding and wintering grassland birds before (1996) and after (1997, 1998) a spring prescribed burn in a mesquite-dominated desert grassland at Buenos Aires National Wildlife Refuge, Arizona. The burn was moderate in intensity, patchy in extent, and affected ground cover more strongly than shrub cover, smaller shrubs more strongly than larger shrubs, and killed 1% of velvet mesquite (Prosopis velutina). Species richness of breeding birds decreased in the first year post-burn. Of breeding species, black-throated sparrows (Amphispiza bilineata) and mourning doves (Zenaida macroura) increased; whereas Botteri's sparrows (Aimophila botterii), Cassin's sparrows (Aimophila cassinii), and pyrrhuloxias (Cardinalus sinuatus) decreased in relative abundance. Breeding species characterized as not shrub-dependent exhibited changes that were more pronounced than those for shrub-dependent species. Of wintering birds, ladder-backed woodpeckers (Picoides scalaris) and vesper sparrows (Pooecetes gramineus) increased, and cactus wrens (Campylorhynchus brunneicapillus) decreased in relative abundance.