Ecological drivers of variation in the extent of the post-fledgling dependence period in raptors

The post-fledgling dependence period (PFDP) is a fundamental stage in the
life cycle of altricial birds that determines their long-term survival and
fitness. However, research on the duration of this period in raptors, and
on the global factors affecting it, is scarce. We performed the
first-of-its-kind literature review on the length of the PFDP in
Accipitridae, the largest family among diurnal raptors, and a
meta-analysis examining the effects of breeding latitude and hemisphere,
body weight, and migratory status, controlling for species’ phylogeny.
Hypotheses were contrasted to the species and population levels. The
length of the PFDP is only known for less than half of Accipitridae
species, with no data for two thirds of the threatened and near-threatened
species. Larger species and individuals breeding in lower latitudes showed
longer PFDPs, as well as non-migrants and southern-hemisphere breeders.
The effect of latitude was more marked in larger species, in resident
populations and in southern hemisphere breeders. This extended PFDP in
larger and tropical raptors may promote juvenile survival. Migration
timing and the effects of continentality in the northern hemisphere
constrain the time available for this period. Results highlight the
importance of encouraging the study of this key, but poorly known, life
cycle stage of raptors.