Are little auks filter-feeders? An experimental approach to test their sensitivity to ongoing climate change RIS ID: 6639

Little auks (Alle alle) are highly vulnerable to environmental modifications in the Arctic. Knowledge of their feeding behaviour and foraging profitability is crucial to predict how these energetically challenged birds will cope with anticipated environme ntal changes, leading to a reduction of the size/energy content of their prey (mostly calanoid copepods). Using an experimental approach, the present project will measure prey intake rates of little auks in relation to prey density and test the hypothesis that birds will filter-feed if prey density is sufficiently high. Little auks will be held temporarily in a dive pool and exposed to different prey densities, while diving/foraging behaviour will be filmed using an underwater video array. Video analysis will enable us to investigate how foraging profitability changes with prey density in little auks, which is crucial for predicting their response to climate change.