Scientists Steve Forrest and Noah Strycker, from Stony Brook University, count chinstraps penguins from an inflatable.
An observer must count every single penguin nest, one by one, and repeat the count three times within a 5% margin to ensure accuracy. It’s often easiest to find a high point with a good view, and use landmarks (like rocks and other terrain features) to visually divide up large chunks of birds.
To understand how penguin populations are faring, a census has been organised by researchers from Stony Brook University, Northeastern University and Greenpeace to study the impact of climate change on fragile chinstrap penguin colonies on Elephant Island in Antarctica.

(This picture was taken in 2020 during the Antarctic leg of the Pole to Pole expedition under the Dutch permit number RWS-2019/40813)