There is an unexpected element of this story that also adds to the picture of how – and why – this region is changing: While the chinstrap population has been declining, the number of macaroni penguins on the island has increased dramatically.
Macaroni penguins, scientists say, are more adaptable, because they have a broader, more flexible diet.
Tracking data from the study showed that the macaronis foraged in warmer waters to the northeast of the island, where scientists say they were were likely to be supplementing their diets with fish and other crustaceans.
Dr Ratcliffe said this shift was “biggest change in community composition ever observed at a single location in Antarctica”.
“Our data shows that the cold-adapted Antarctic chinstrap species are no longer thriving beside their sub-Antarctic neighbours,” he added.
“It is further evidence of how rapid warming in the Antarctic is impacting unique and sensitive ecosystems.”
As for the title of world’s largest penguin colony, scientists say that is now held by a site more than 5,000km away – on the other side of the Antarctic continent – Cape Adare in the Ross Sea.
The research is published in the journal Current Biology, external.