STABLE ISOTOPE ANALYSIS OF FALL MIGRATION STOPOVER BY SIX PASSERINE SPECIES IN AN INLAND PITCH PINE-SCRUB OAK BARREN

We conducted mist-net surveys of migrating songbirds during fall migration 2007-2009 on the 1,300-ha Albany Pine Bush Preserve (APBP), a fire-managed inland pitch pine scrub oak (Pinus rigida-Quercus spp.) barren in east-central New York. We banded 244 migrating passerines from 32 non-resident species in 8,610 net/m/hr documenting use of northeastern pine barrens as stopover sites for passerines with diverse breeding ecologies. We estimated the breeding site origin of six species (a kinglet, four warblers, and a sparrow) using stable hydrogen isotope measurements from flight feathers. There was a broad range of isotope ratios within each species indicating a large catchment area extending several hundred kilometers north and west of the stopover site. Over half the birds originated >750 km from the APBP. We found no evidence for geographical structure of the timing of migration through APBP; slopes of regression lines for capture date versus hydrogen isotope ratio from feathers (delta D-f) were not statistically different from zero. This contrasts with previous isotope research that reports both leapfrog and chain migration patterns by different warbler species at stopover sites in the western United States. Received 29 October 2010. Accepted 4 March 2011.