Response of Breeding Florida Grasshopper and Bachman's Sparrows to Winter Prescribed Burning

Abstract

Populations of Florida grasshopper (Ammodramus savannarum floridanus) and Bachman's sparrows (Aimophila aestivalis) are small and declining. Prescribed burning is the primary management tool used to maintain their grassland habitats, but the effects of this management practice on the breeding density and reproductive success of these populations are poorly understood. We conducted a 3-year spot-mapping study of 3 winter burn classes (0.5-yr, 1.5-yr, and 2.5-yr postfire) in native dry prairie on 2 sites in central Florida to determine the effects of fire management on breeding density and reproductive success of these 2 sparrows. Florida grasshopper sparrow densities were greater on recently burned plots (0.5 yr postburn: x = 4.0 ± 1 territories/10 ha (x ± SE); 1.5 yr postburn x = 3.4 ± 0.8 territories/10 ha) than on plots that had not been burned in 2.5 years (x = 1.8 ± 0.8 territories/10 ha). Grasshopper sparrow reproductive success was also higher in recently burned plots (0.5 yr postburn; x = 1.6 successful territories/plot) than in 2.5-year burn plots (x = 0.6 successful territories/plot). In contrast, Bachman sparrow breeding densities and reproductive success were not affected by fire management rotation. Our results indicate that a fire rotation of ≤3 years is necessary to maintain suitable breeding habitat for Florida grasshopper sparrows but does not appear to negatively affect breeding Bachman's sparrows.