Remating opportunities and low costs underlie maternal desertion

Parental care can enhance offspring survival but may impose significant
costs to parents. The costs and benefits of care are key to understanding
patterns of parental care, where parents can benefit by having their
partner increase investment in care, while reducing their own effort.
However, investigating the costs and benefits of parental care in wild
populations is challenging. Here we use highly detailed behavioural
observations in families of a small shorebird, where one parent frequently
deserts its offspring, to explore the potential costs and benefits of
desertion in a wild population. We firstly show that females desert their
broods more frequently than males. Secondly, we investigate the benefits
of this frequent female desertion in terms of additional mating
opportunities, and the costs of desertion to females in terms of the
growth and survival of deserted offspring. Our results indicate that
female desertion is favoured by a combination of remating benefits and a
lack of costs to brood growth and survival, as abandoned male parents
continue to provide care after desertion. Our results shed light on the
costs and benefits underlying natural desertion strategies and suggest
that female desertion is a fine-tuned behaviour that responds to
seasonally changing benefits of desertion.