We apply Foosa at the scale of interactions among the 3 breeding penguin colonies, krill, and environmental variability at the long-term research site in Admiralty Bay, King George Island. This work-in-progress serves 2 purposes: 1) to use historical data to estimate parameters in a model-fitting framework for the purpose of model validation, and 2) to add and explore functionality in Foosa to investigate alternative, competing hypotheses about juvenile penguin survival. Our preliminary results suggest that Foosa capably captures the general trends in adult abundance at Admiralty Bay with minimal formal estimation. Preliminary examination of top-down and bottom-up forcing on juvenile penguin survival further helps to explain trends in adult abundance. From a bottom-up perspective, there appears to be a trade-off between per-capita productivity at low adult abundance and the sensitivity of juvenile survival to foraging conditions during the first winter of life. From a top-down perspective, strong depensatory stock-recruitment dynamics suggest that understanding predatory effects on juveniles may be fundamental for understanding penguin dynamics at our study colony. To better capture the inter-annual variability in the adult abundance data, we propose future work that includes, inter alia, expanding the spatial scope to account for seasonal movement of the penguins, incorporating alternative environmental drivers, and continued hypothesis testing to make strong inference about the dominant drivers of the penguins at Admiralty Bay.
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