Can macaroni penguins keep up with climate- and fishing-induced changes in krill?

Macaroni penguins have evolved to cope with the highly variable conditions of the Southern Ocean. However, changes in prey supply and patchiness potentially associated with changes in climate and krill fishing activity may be occurring too rapidly for the penguins to adapt. We use a stochastic dynamic programming model to examine how changes in both the mean and patchiness of krill supply may affect the foraging decisions, and therefore breeding success, of female macaroni penguins at South Georgia. We predict that rapid changes in the mean supply of prey will have more of an effect on the condition of the female and chick than changes in prey patchiness, and that changes in foraging behavior compensate for changes in prey up to a threshold point, beyond which breeding success is likely impacted. In particular, we predict that the location of the threshold is affected by whether or not the penguins are adapted to the prey environment in which they are foraging, with the female and chick receiving on average 20% less of their daily energetic requirement if the female is not foraging optimally.