Behaviour 2019
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Optimizing Embryonic Development: Modelling the Incubation-Foraging Trade-Off  
Alexandra G. Cones, Dakota Coomes, Philip H. Crowley. University of Kentucky, Lexington, KY, United States

How parents manage embryonic development is an understudied but essential early step in reproductive success. For the oviparous homeotherms of interest here, this requires balancing a trade-off between incubation and foraging, whether one or both parents participate in incubating eggs. In this modeling analysis, taking account of differences between altricial and precocial species—represented here by house sparrows and wood ducks, respectively—we find that mortality risk in the egg stage can strongly interact with survival in the nestling stage for altricial species. The benefits of supplementary nest attentiveness in the altricial case may account for males accepting the opportunity costs of providing joint care of both eggs and chicks. A seasonal clutch-size decline is more likely to result from a cumulative female fecundity cost between clutches in the altricial case and from delayed nesting by females of lower quality in the precocial case. These results highlight both the importance of downstream consequences between life stages on optimal parental decisions and how optimal parental decisions can vary by species-specific physiology and ecology.