Quantifying the causes and consequences of variation in satellite‐derived population indices: a case study of emperor penguins

Very high-resolution satellite (VHR) imagery is a promising tool for estimating the abundance of wildlife populations, especially in remote regions where traditional surveys are limited by logistical challenges. Emperor penguins Aptenodytes forsteri were first species to have circumpolar population estimate derived via VHR imagery. Here we address an untested assumption from Fretwell et al. (2012) that single image emperor penguin colony reasonable representation year was taken. We evaluated satellite-related and environmental variables might influence calculated area pixels reduce uncertainties satellite-based estimates populations future. focused our analysis on multiple images three representative colonies: Atka Bay, Stancomb-Wills (Weddell Sea sector) Coulman Island (Ross between September December during 2011. replicated methods (2012), which included using supervised classification tools ArcGIS 10.7 software calculate occupied (hereafter referred as ‘population indices’) each image. found indices varied 2 nearly 6-fold, suggesting pixel areas may not provide complete understanding size year. Thus, further highlight important roles of: (i) sun azimuth elevation through resolution (ii) patchiness (aggregated vs. distributed) areas. effect wind temperature patchiness. Despite intra-seasonal variability indices, simulations indicate reliable, robust trends possible including covariates aggregating across time space. Our work provides additional parameters should be future models penguins.