Climate change shifts Antarctic penguin breeding earlier by up to two weeks

Antarctic penguins are beginning their breeding season about two weeks earlier as a result of climate change, marking the largest timing shift ever recorded, according to research published Tuesday.

The study, published in the Journal of Animal Ecology, analyzed breeding patterns of Adelie, Chinstrap and Gentoo penguins from 2012 to 2022, using the date when colonies were first continuously occupied as a key indicator.

Researchers said climate change is likely to create "winners and losers," with warming conditions favoring more adaptable species such as Gentoo penguins over krill-dependent Chinstraps and ice-dependent Adelies.

The analysis drew on data from 77 time-lapse cameras installed at 37 colonies across Antarctica and sub-Antarctic islands. It found record advances in breeding timing for all three species, led by Gentoo penguins, which began breeding an average of 13 days earlier per decade and up to 24 days earlier at some colonies.

Researchers said this represents the fastest phenological shift ever documented in any bird species, and possibly in any vertebrate.

Adelie and Chinstrap penguins also began breeding about 10 days earlier on average. However, scientists said the precise drivers remain unclear, pointing to possible factors including rising temperatures, earlier ice breakup and snowmelt, and earlier phytoplankton blooms.

The study also found that penguin colony sites are warming at roughly four times the Antarctic average, making them among the fastest-warming habitats on Earth.

Penguins play a critical role in Antarctic food webs by transporting nutrients from deep waters to the surface, supporting algae growth and broader ecosystem productivity. Scientists warned that declines in penguin populations could trigger cascading effects across the Antarctic ecosystem.