Sea ice predicts long-term trends in Adélie penguin population growth, but not annual fluctuations: Results from a range-wide multi-scale analysis

• Published in: Global Change Biology
• Main Authors: Iles, David, Lynch, Heather, Ji, Rubao, Barbraud, Christophe, Delord, Karine, Jenouvrier, Stéphanie
• Other Authors: Canadian Wildlife Service, Environment and Climate Change Canada, Stony Brook University SUNY (SBU), State University of New York (SUNY), Biology Department - Woods Hole Oceanographic Institution, Woods Hole Oceanographic Institution (WHOI), Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Biology Department (WHOI)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: Antarctica; environmental variation; habitat suitability; niche; predictability; state-space; stochastic; uncertainty; [SDE]Environmental Sciences; Antarc*; Sea ice
• Online Access: https://hal.science/hal-02545851; https://doi.org/10.1111/gcb.15085

International audience Understanding the scales at which environmental variability affects populations is critical for projecting population dynamics and species distributions in rapidly changing environments. Here, we used a multi‐level Bayesian analysis of range‐wide survey data for Adélie penguins to characterize multi‐decadal‐ and annual effects of sea ice on population growth. We found that mean sea ice concentration at breeding colonies (i.e., “prevailing” environmental conditions) had robust non‐linear effects on multi‐decadal population trends and explained over 85% of the variance in mean population growth rates among sites. In contrast, despite considerable year‐to‐year fluctuations in abundance at most breeding colonies, annual sea ice fluctuations often explained less than 10% of the temporal variance in population growth rates. Our study provides an understanding of the spatially and temporally dynamic environmental factors that define the range limits of Adélie penguins, further establishing this iconic marine predator as a true sea ice obligate and providing a firm basis for projection under scenarios of future climate change. Yet, given the weak effects of annual sea ice relative to the large unexplained variance in year‐to‐year growth rates, the ability to generate useful short‐term forecasts of Adélie penguin breeding abundance will be extremely limited. Our approach provides a powerful framework for linking short‐ and longer‐term population processes to environmental conditions that can be applied to any species, facilitating a richer understanding of ecological predictability and sensitivity to global change.