Incubation temperature and social context affect the nest exodus of precocial ducklings

The environments that animals experience during development have important fitness consequences. In birds, parents influence the developmental environment of their offspring through incubation. Subtle changes in incubation temperature affect offspring morphology and physiology, such as growth, immune function, and thermoregulation, yet little is known about how it may affect critical early-life behaviors. Because expression of behavior can be influenced by the social environment, the effect of incubation temperature on behavior may be context-dependent. We investigated whether incubation temperature and social context influence a critical early-life task in wood ducks (Aix sponsa). Wood ducks nest in tree cavities and, shortly after hatching, ducklings must jump and climb out of the cavity. Failure to exit the nest is fatal. In two experiments, we incubated eggs at different mean temperatures and examined the nest exodus of ducklings individually and in mixed-incubation temperature pair...