(CNN)Penguin colonies in some parts of the Antarctic have declined by more than 75% over the past half century, largely as a result of climate change, researchers say.
Scientists discovered that colonies of chinstrap penguins -- also known as ringed or bearded penguins -- have dropped dramatically since they were last surveyed almost 50 years ago.
Every colony surveyed on Elephant Island, an important penguin habitat northeast of the Antarctic Peninsula, experienced a population fall, according to independent researchers who joined a Greenpeace expedition to the region.
Chinstrap penguin colony in front of a glacier on Elephant Island in Antarctica.
At the last survey in 1971, there were 122,550 pairs of penguins across all colonies on Elephant Island. But the recent count revealed just 52,786 pairs -- a drop of almost 60%.
The size of the population change varied from colony to colony on Elephant Island. The biggest decline -- 77% -- was recorded at a colony known as Chinstrap Camp.
Climate change has led to reduced sea ice and warmer oceans, which has meant less krill, the main component of the penguins' diet.