Data from: Heterogeneity in breeding productivity is driven largely by factors affecting nestlings and young fledglings in an imperiled migratory passerine

Identifying factors that drive variation in vital rates among populations
is a prerequisite to understanding a species’ population biology and,
ultimately, to developing effective conservation strategies. This is
especially true for imperiled species like the golden-winged warbler
(Vermivora chrysoptera) that exhibit strong spatial heterogeneity in
demography and respond differently to conservation interventions. Habitat
management actions recommended for breeding grounds conservation include
timber harvest, shrub shearing, and prescribed fire that maintain or
create early successional woody communities. Herein, we assessed variation
in the survival of nests [n=145] and fledglings [n=134] at 17 regenerating
timber harvests sites within two isolated populations in Pennsylvania that
differed in productivity and response to habitat management. Although
overall survival of nests and fledglings was higher in the eastern
population than the central population, this was only true when the nest
phases and fledgling phases were considered wholly. Indeed, survival rates
of nestlings and recently fledged young (1-5 days post-fledging) were
lower in the central population, whereas eggs and older fledglings (≥ 6
days post-fledging) survived at comparable rates in both populations.
Fledglings in the central population were smaller (10% lower weight) and
begged twice as much as those in the eastern population, suggesting food
limitation may contribute to lower survival rates. Fledgling survival in
the central population, but not eastern, also was a function of habitat
features (understory vegetation density [+] and distance to mature forest
[-]) and individual factors (begging effort [-]).Our findings illustrate
how identifying how survival varies across specific life stages can
elucidate potential underlying demographic drivers, such as food resources
in this case. In this way, our work underscores the importance of studying
and decomposing stage-specific demography in species of conservation
concern.