Intrinsic and extrinsic factors that influence fledgling survival of a migratory songbird in the Southern Appalachians

Abstract

The Black-throated Blue Warbler (Setophaga caerulescens) is a Neotropical migrant songbird that breeds in eastern North America. From 2011-2012, I examined fledgling survival and habitat selection for this species at the southern limit of its breeding range in the Nantahala National Forest, North Carolina, USA. I observed 222 uniquely-marked Black-throated Blue Warbler fledglings and collected data on habitat characteristics and food availability (larval insects). An interaction between fledge date and food was most important in explaining fledgling survival, indicating a potential sensitivity of survival to phenological mismatches caused by climate change. To investigate fledgling habitat use, I compared shrub density at fledgling locations with available habitat. Fledglings of older warblers were found in areas of greater evergreen shrub density than fledglings of younger parents. My results suggest that intrinsic individual qualities and extrinsic habitat characteristics can affect fledgling survival and should be simultaneously considered in future studies.