Use of a new model to quantify compromises between embryo development and parental self-maintenance in three species of intermittently incubating passerines

Abstract

1. Instead of just times to cool ( t cool) and heat ( t heat), intermittent incubation cycles contain a period ( t equil) when eggs are kept at relatively high equilibrium temperatures after heating. 2. Relative allocations favoring parental self-maintenance [when ( t cool+ t heat)> t equil] versus embryo development [when ( t cool+ t heat)< t equil] were measured for house wrens ( Troglodytes aedon), tree swallows ( Tachycineta bicolor) and black-capped chickadees ( Poecile atricapillus). 3. Wrens showed over-all significant relative allocation to parental self-maintenance, while chickadees and swallows balanced both functions. 4. House wrens gradually shifted allocation toward increased average egg temperature as incubation progressed, calling into question how temperature influences development rate.