CONCLUSION
Based on a global-scale synthesis
of avian survival rates, we find evidence that survival increases with
decreasing latitude, but that this phenomenon is more nuanced than
previous descriptions have characterized. Specifically, we demonstrate
that the latitudinal survival gradient is stronger in northern
hemisphere species, where climate seasonality may be greater. By
including aspects of species life history traits in our models, we could
explain a greater portion of the variation in survival rates than with
latitude alone. These results indicate the importance of considering an
organism’s intrinsic traits as well as the extrinsic factors of their
environment when describing broad-scale macroecological patterns. Where
peaks in survival occur, how they relate to climatic variables, and how
these patterns are likely to change through time and space given the
effects of climate change, are of major importance for conservation. We
hope that in assembling this database and dissecting some of the global
patterns in survival across avian groups and hemispheres, we can provide
a platform for future work to target underrepresented regions and taxa
and also make a clear path forward to better understanding variation in
survival rates, and how it intersects with other life history traits
across the world’s avifauna.