Interactive effect of temperature-induced energetic benefits and shifts in feeding conditions on parental care strategie
For endotherms living in cold climates, warming temperatures associated with climate change may present energetic benefits. These benefits may lead to shifts in patterns or success of parental care. Life history theory suggests that long-lived organisms should favor investment in future fitness potential, in some cases at the expense of current fitness potential; this is especially important as we consider energetically costly parental care activities. We focused our study on a long-lived burrow-nesting seabird, Leach’s storm-petrel (Oceanodroma leucorhoa), which has a prolonged parental care period for a single clutch per year. Air temperature increases are expected to decrease metabolic needs during incubation and may alleviate negative consequences of temporary parental absence from the nest (e.g., reduced temperature loss of eggs and reduced chick metabolism). We developed a stochastic dynamic state-variable model to investigate effects of increased burrow temperature on both the optimal parental-care strategy and the lifetime fitness consequences of historical parental-care strategies. Although climate change is expected to affect food resources as well, our ability to predict the magnitude and even direction of this for Leach’s storm-petrel is poor. As a consequence, we have repeated the initial analysis under varying expectations of foraging conditions.
Our results suggest that increased burrow temperatures will not only reduce metabolic costs of adults during the incubation period by up to 33%, but could allow adults to provide less care during incubation for similar levels of lifetime fitness, due to enhanced hatching and fledging rates. The impact of temperature on food availability caused greater shifts in optimal parental care strategies than increase in burrow temperature. Even in the face of energy savings from reduced parental-care costs, parents were unable to compensate for increased foraging duration requirements in simulations with negative shifts in food availability. Our results suggest that if declines in lower trophic level ocean productivity result in increased foraging time requirements for adult seabirds, then abandonment rates of offspring may increase and fledging success may decrease. Further research on the foraging duration requirements of seabirds and how temperature-induced changes in ocean productivity will affect these requirements is warranted.