Marie-Charlott Rümmler

Emperor penguins (Aptenodytes forsteri) breed on the remote coastlines of Antarctica under the extreme conditions of the polar winter. Consequently, the majority of their colonies have never been visited by humans. Anthropogenic climate change and the associated profound shifts in the Antarctic ecosystem now threaten the survival of the species. Due to the extreme remoteness of these colonies, most current population estimates rely on satellite imagery or aircraft surveys, both of which are subject to considerable uncertainties.,In this study, we investigate for the first time the suitability of aerial drones for determining the population size of emperor penguin colonies. To this end, the Atka Bay colony was surveyed multiple times with an aerial drone during a single breeding season. In addition, we evaluated data from 13 aircraft surveys across 5 emperor penguin colonies in Queen Maud Land collected between 2022 and 2025. Our analysis focused on quantifying observer error and modelling breeding pair numbers based on counts of individuals.,As a result, we provide what are likely the most accurate breeding pair estimates for these colonies to date. We also quantified the distinct influence of ground resolution, lighting conditions, and guano staining on observer error. Our findings demonstrate that drones are highly suitable for surveying local emperor penguin colonies, while also highlighting that deriving breeding pair estimates from the number of individuals at the end of the season remains subject to substantial uncertainty.

Due to the remote location of colonies of Antarctic shags (Phalacrocorax(atriceps)bransfieldensis) in Antarctica, there is only sparse data on the abundance of this species. An unmanned aerial vehicle (UAV) survey for known and unknown Antarctic shag colonies along the coasts of Nelson Island and western King George Island, Antarctica, was conducted in December 2016. Four colonies, one of them previously unknown, were detected. For the first time since the 1980s, the total population size of the colonies in that area was determined. A comparison with previous estimates revealed evidence of a population increase by a factor of 2.86. To support future survey campaigns, several characteristic features of Antarctic shag colonies, nests and individuals in aerial imagery were identified. This makes possible more reliable detection and determination of population size in Antarctic shag colonies. These characteristic features were compared with those of chinstrap penguin colonies (Pygoscelis antarcticus) because these species often overlap spatially and are difficult to distinguish. In addition, the optimal weather conditions and flight parameters for an aerial survey were specified.