Retreating Shorelines as an Emerging Threat to Adélie Penguins on Inexpressible Island

Abstract

Long-term observation of penguin abundance and distribution may warn of changes in the Antarctic marine ecosystem and provide support for penguin conservation. We conducted an unmanned aerial vehicle (UAV) survey of the Adélie penguin (Pygoscelis adeliae) colony on Inexpressible Island and obtained aerial images with a resolution of 0.07 m in 2018. We estimated penguin abundance and identified the spatial extent of the penguin colony. A total of 24,497 breeding pairs were found on Inexpressible Island within a colony area of 57,507 m2. Based on historical images, the colony area expanded by 30,613 m2 and abundance increased by 4063 pairs between 1983 and 2012. Between 2012 and 2018 penguin abundance further increased by 3314 pairs, although the colony area decreased by 1903 m2. In general, Adélie penguins bred on Inexpressible Island at an elevation <20 m, and >55% of penguins had territories within 150 m of the shoreline. This suggests that penguins prefer to breed in areas with a low elevation and close to the shoreline. We observed a retreat of the shoreline on Inexpressible Island between 1983 and 2018, especially along the northern coast, which may have played a key role in the expansion of the penguin colony on the northern coast. In sum, it appears that retreating shorelines reshaped penguin distribution on the island and may be an emerging risk factor for penguins. These results highlight the importance of remote sensing techniques for monitoring changes in the Antarctic marine ecosystem and providing reliable data for Antarctic penguin conservation.

UAVs for Science in Antarctica

“…The identification of the ponds can be guided by UAV surveys which can provide their description and of the surroundings with detailed images and elevation maps, as shown by Faucher et al (2021) [74]. In another monitoring procedure, Chen et al (2021) [75] compared aerial photos with current UAV surveys to quantify the retreat of about 12 m of the shoreline in 30 years in Inexpressible Island in the Ross Sea, and how it is impacting wildlife, by identifying the change of location of Adélie penguin colonies in the island.…”

A Deep Learning Based Method to Delineate the Wet/Dry Shoreline and Compute Its Elevation Using High-Resolution UAS Imagery

“…UAS provide fast and timely data acquisition of the wet/dry shoreline conditions. Additionally, UAS allow the collection of very high-resolution imagery, given their proximity to the ground, focused on the region of interest [29]. Imagery collected at lower altitudes results in higher ground sample distance (GSD), and any error in predicted features within the image will be significantly lower than the error from satellite imagery, on the order of as low as a few centimeters for UAS imagery.…”