Spatial Occupancy and Abundance Trends of Endangered Florida Grasshopper Sparrows at Three Lakes Wildlife Management Area

摘要

We analyzed spatiotemporal variations in point counts of Ammodramus savannarum floridanus (Florida Grasshopper Sparrow) at Three Lakes Wildlife Management Area (WMA) during 2003-2012 to provide a detailed report of population changes during that period. There were significant increases in estimates of occupancy probability and abundance of Florida Grasshopper Sparrows at count points in some parts of Three Lakes WMA from 2003 to 2008 followed by significant reductions in these estimates from 2008 to 2012. Inconsistent, finer-scale population fluctuations appeared to be occurring within these time periods. From 2003 to 2012, estimates of overall change in occupancy probability and abundance of the Florida Grasshopper Sparrows at count points were largely negative throughout the area, hut a region in the northeast portion of the WMA may offer the greatest chance for population persistence. The count points characterized by most persistent occurrence and abundance were >= 600 m from the edge of non-prairie habitat, at higher elevations (18.5-19.0 m above sea level), and associated with areas burned within the previous 2 years. Causes for the overall population decline are unknown, hut appear to he acting over the entire range of the Florida Grasshopper Sparrow.