The role of mortality risk in parental behaviour

Background: A parent feeding its young during the breeding season faces a trade-off between mortality risk and provisioning young with food for growth.

Question: How should the parent behave to maximize reproductive success when mortality to both parent and young are considered?

Mathematical method: Using an optimality model, we establish new formulae to describe parental behaviour when there is a trade-off between growth rate of the young and mortality risk to both parent and young.

Key assumptions: We consider mortality functions for both parent and young. These comprise the sum of a background mortality risk and a mortality risk attributed to parental behaviour.

Conclusions: Mortality is an important parameter in the determination of parental behaviour. As the dependence of the mortality of the young on parental effort grows, a parent should invest a greater proportion of time in being vigilant for predators. An increase in other mortality parameters prompts the opposite effect. Mortality should be described by multiple parameters to predict fully how a parent should behave.