Climate presses and pulses mediate the decline of a migratory predator

Abstract

Long-term climate changes and extreme climate events differentially impact animal populations, yet whether and why these processes may act synergistically or antagonistically remains unknown. Disentangling these potentially interactive effects is critical for predicting population outcomes as the climate changes. Here, we leverage the "press-pulse" framework, which is used to describe ecological disturbances, to disentangle population responses in migratory Magellanic penguins to long-term changes in climate means and variability (presses) and extreme events (pulses) across multiple climate variables and life history stages. Using an unprecedented 38-y dataset monitoring 53,959 penguins, we show for the first time that the presses and pulses of climate change mediate the rate of population decline by differentially impacting different life stages. Moreover, we find that climate presses and pulses can work both synergistically and antagonistically to affect animal population persistence, necessitating the need to examine both processes in concert. Negative effects of terrestrial heat waves (pulses) on adult survival, for example, were countered by positive effects of long-term changes in oceanographic conditions in migratory grounds (presses) on juvenile and adult survival. Taken together, these effects led to predicted population extirpation under all future climate scenarios. This work underscores the importance of a holistic approach integrating multiple climate variables, life stages, and presses and pulses for predicting the persistence of animals under accelerating climate change.