This repository outlines the code and process for analysing Ross Sea emperor penguin population dynamics from satellite imagery over 20-years+ from 2000-2024.

The paper is currently in review, entitled, "Evidence of emperor penguin sensitivity to sea ice fluctuations"

We estimated abundance indices for each of the seven colonies in the Ross Sea, and the overall metapopulation, using the LaRue et al. (2024) Bayesian state-space model (found here: https://github.com/davidiles/EMPE_Global/tree/main/analysis). We then calculated population growth rates from estimated abundance indices and ran a series of analyses to determine population synchrony and investigate environmental drivers of change.

The code also included how we extracted sea ice concentration anomalies (SICa) from large-scale SIC data (access through NSIDC), including how we calculated the seasonal averages and the anomalies (how each month compares to the monthly average between 1995-2024).

Our data file that includes all population abundance index estimates: EP_data_FINAL_roc.csv

Code for recreating our SICa extraction process: SIC_extractAnomalise_2025.R

Code for recreating our population figures, change point detection, and running synchrony analyses: population_figs.R

Code for rerunning our Generalised Additive Models (for the metapopulation and colony-specific GAMMs): GAM_modelling.R