Plasticity of incubation behaviors helps Wood Ducks (Aix sponsa) maintain an optimal thermal environment for developing embryos

Abstract

ABSTRACT Optimal development of avian embryos occurs within a narrow range of incubation temperatures. Most parents that physically incubate their eggs through direct contact are challenged to balance their time on the nest with taking foraging recesses to satisfy their energetic requirements. To explore the costs and investment strategies of incubating female Wood Ducks (Aix sponsa), we manipulated the microclimate of nests by reducing down insulation from the typical 4.0 g to 0.5 g. Cooling rates of clutches during morning recesses increased when down insulation was reduced, especially at low ambient temperatures. Females with reduced down responded to increased cooling rates by shortening morning recesses and increasing daily incubation constancy, and these behavioral changes were independent of their body mass at the start of incubation. Females in both treatment groups responded similarly to changes in ambient temperature and spent less time incubating as ambient temperatures increased. Clutch temper...