Natal Philopatry and Juvenile Survival in Swainson's Warblers (Limnothlypis swainsonii)

摘要

Understanding natal dispersal and rates of philopatry can help provide minimum estimates of juvenile survival, a vital demographic parameter for which little information is available. However, despite the large number of hatch-year migratory birds banded every year at their natal sites, few are resighted or recaptured. Here, we report on the return of 22 Swainson's Warblers (Limnothlypis swainsonii) banded as nestlings or fledglings between 1997-2008 at breeding sites in Arkansas, North Carolina, and South Carolina, USA. Of 284 nestling Swainson's Warblers banded, we found 13 (4.6%) exhibiting natal philopatry. Of 95 fledglings banded, we detected 9 (9.5%) in later years. The median distance moved from the original capture to an encounter location the subsequent breeding season for all second-year birds we detected was 1.5 km (range = 54 m to 15.4 km). The mark-recapture estimate for first-year apparent survival was 0.119 (SE = 0.032). Estimated recapture probability was between 0.55 and 0.65. Only one returning juvenile we detected was female. Assuming a 50:50 sex ratio, the annual apparent (i.e., minimum) survival estimate for first-year males was 0.238. Body mass, wing size, and banding date were not good predictors of whether a juvenile would return to the site the following year, and there was no evidence of differences among study sites. Because land use and hydrology limits suitable habitat, Swainson's Warbler populations at our study sites were mostly isolated from other suitable habitats and populations; thus, individuals of this species may benefit from natal philopatry more than most passerines.