A meta-analysis of global avian survival across species and latitude

Abstract

Tropical birds are purported to be longer lived than their temperate counterparts, but it has not been shown whether avian survival rates covary with latitude worldwide. Here, we perform a global-scale meta-analysis of 1,007 estimates from 249 studies of avian survival and demonstrate that a latitudinal survival gradient exists in the northern hemisphere, is dampened or absent for southern hemisphere species, and that differences between passerines and nonpasserines largely drive these trends. We also show that while extrinsic factors related to climate were poor predictors of survival compared to latitude alone, the relationship between survival and latitude is strongly mediated by intrinsic traits ― larger species with smaller clutch size had the highest survival. Taken together, our results suggest that interactions between intrinsic traits and lineage-specific effects surpass latitude and its underlying climatic factors in explaining global patterns of avian survival.