Tracking Wintertime Behaviour of Emperor Penguins Using High‐Resolution Synthetic Aperture Radar Imagery

Abstract

Gaining insight into population changes of species in remote areas of the world poses challenges, often resulting in opportunistic observations (convenience sampling) that limit scientific inference. Remote sensing resources, typically high‐resolution optical imagery, have revolutionised population ecology especially in polar regions like Antarctica and now many species have been censused. However, estimates based on remote sensing often remain limited to convenience sampling, rather than allowing observation at times of year that provide more information about the breeding population. Here we introduce a proof of concept using high‐resolution synthetic aperture radar (SAR) imagery to detect, enumerate and track behaviours of emperor penguins during the Antarctic winter. Using 25–30 cm Umbra SAR imagery, we gathered images at six colonies of emperor penguins during winter 2024 to determine phenology, to gain insight to the breeding population and advance a new method for breeding population observations. We found that emperor penguins are identifiable on fast ice and that SAR‐based observations match concurrent field observations (at Atka Bay). Total huddle area correlated with average colony size at emperor penguin colonies, and we found that larger colonies tended to use more space on the fast ice than smaller colonies. We demonstrate that the breeding population of emperor penguins during winter can be estimated using a combination of SAR imagery with phenological‐behavioural models. Given that models suggest emperor penguins may be quasi‐extinct before 2100, our work provides an important next step in understanding the approximate size and phenology of the breeding population, information that would be required for conservation of the species and for area‐based conservation such as evaluation of the Ross Sea Marine Protected Area (MPA), where ~33% of emperor penguins exist.