American Society of Naturalists

A membership society whose goal is to advance and to diffuse knowledge of organic evolution and other broad biological principles so as to enhance the conceptual unification of the biological sciences.

“A physiological signature of ‘cost of reproduction’ associated with parental care”

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Melinda A. Fowler and Tony D. Williams

Birds pay a cost of reproduction when pushed and now we know the physiological basis of this cost

A female European starling (<i>Sturnus vulgaris</i>) returning with food for her chicks.<br />(Credit: Melinda A. Fowler and Tony D. Williams)
A female European starling (Sturnus vulgaris) returning with food for her chicks.
(Credit: Melinda A. Fowler and Tony D. Williams)

Every parent knows that bringing up children can, at times, be really hard work. But is parental care also hard work for other animals? Could parental care even kill you? And if so how? Melinda Fowler and Tony Williams (2017), of Simon Fraser University, address these questions by making female European starlings work harder while feeding their chicks. They clipped some flight feathers to reduce wing area and attached radio-transmitters to increase body mass. Even though the manipulated females must have had higher flight costs they kept working as hard as other birds, making the same number of visits to the nest to feed chicks, and rearing as many offspring. However, wing-clipped females paid a cost for this parental effort: They did less well in their subsequent breeding attempt and had lower survival to the following year. Moreover, there was a clear physiological signature of this cost females paid. Wing-clipped females had lower oxygen-carrying capacity, lower energy reserves, decreased immune function, and elevated levels of oxidative stress – all signs of poor physiological condition. So hard work during parental care can involve a widespread decline in function across multiple physiological systems: rearing kids could lead to cumulative “wear and tear” on the body and perhaps even decrease lifespan! Read the Article