Data from: Adult mortality probability and nest predation rates explain parental effort in warming eggs with consequences for embryonic development time

Parental behavior and effort vary extensively among species. Life history
theory suggests that age-specific mortality could cause this interspecific
variation, but past tests have focused on fecundity as the measure of
parental effort. Fecundity can cause costs of reproduction that confuse
whether mortality is the cause or consequence of parental effort. We focus
on a trait, parental time and effort in warming embryos, which varies
widely among species of diverse taxa and is not tied to fecundity. We
conducted studies on songbirds of four continents and show that time spent
warming eggs varies widely among species and latitudes, and is not
correlated with clutch size. Adult and offspring (nest) mortality
explained most of the interspecific variation in time and effort that
parents spend warming eggs measured by average egg temperatures. Parental
effort in warming eggs is important because embryonic temperature can
influence embryonic development period and, hence, exposure time to
predation risk. We show through correlative evidence and experimental
swapping of embryos between species that parentally induced egg
temperatures cause interspecific variation in embryonic development
period. The strong association of age-specific mortality with parental
effort in warming eggs and the subsequent effects on embryonic development
time are unique results that can advance understanding of broad geographic
patterns of life history variation.