Data from: A wide range of abiotic and biotic variables leaves most variation in bird nest architecture unexplained

Nests are the locations or containers for offspring, and mediate
interactions between offspring and the environment. However, understanding
how environmental factors shape the evolution of nest architecture is
complicated. In particular, the relative contributions of biotic (e.g.,
protection from predation) and abiotic (e.g., microclimate maintenance)
factors to the evolution of nest architecture have not been clearly
quantified, and multiple nest traits, such as their location or shape, are
rarely considered together. Here, we use a dataset of 3,685 bird species
with complete data across five different nest traits (out of a wider
dataset of 10,528 species included in the repository), to characterise a
multivariate ‘morphospace’ of nest architecture. We achieve this using
ordination methods, namely a principal coordinate analysis. Then, we use
all derived axes of variation in nest morphospace and multivariate
phylogenetic comparative methods used for geometric data to explore
whether abiotic or biotic factors better explain the variation observed in
ordination-derived nest architecture. We detect that abiotic
environmental factors (climate) explain more variation than biotic
factors. However, substantial variation in nest architecture remains
unexplained after accounting for the variables used here, suggesting that
commonly used nest traits may not capture covariation between nest
architecture and the environment as expected. Nonetheless, our study
demonstrates how nest evolution is affected by the environment on a global
scale, which will form a foundation to explore a more diverse array of
nest traits and environmental variables, to understand nest evolution in
the world’s birds.