Penguins breed earlier than ever in warming Antarctica

Penguins in Antarctica are dramatically shifting the timing of their breeding seasons in response to climate change, raising fresh concerns about their long-term survival, according to new research.

A decade-long study led by Penguin Watch at the University of Oxford and Oxford Brookes University has found that some penguin populations are now breeding more than three weeks earlier than previously recorded. The findings, published on January 20 in the Journal of Animal Ecology, suggest the changes are happening at unprecedented speed and could disrupt access to food for penguin chicks, The Guardian shares. 

“We are very concerned because these penguins are advancing their season so much, and penguins are now breeding earlier than in any known records,” said the study’s lead author, Dr Ignacio Juarez Martínez. “The changes are happening so fast that the penguins could end up breeding at times when their prey is not available yet. This could result in a lack of food for the penguin chicks in the first weeks of their life, which could be fatal. Even if the penguins could match their prey’s behaviour, we can’t expect them to keep this pace up much longer.”

Researchers examined breeding patterns between 2012 and 2022, focusing on when penguins first settled continuously at nesting colonies. The study covered three species — Adélie, chinstrap and gentoo penguins — across 37 colonies in Antarctica and nearby sub-Antarctic islands. Colony sizes ranged from just a dozen nests to several hundred thousand.

Data were collected using 77 time-lapse cameras, each recording images and air temperature throughout the breeding season. The results show that all three species are breeding earlier, but gentoo penguins experienced the most dramatic shift.

On average, gentoo breeding advanced by 13 days over the decade, with some colonies shifting by as much as 24 days — the fastest change in breeding timing ever recorded in any bird, and possibly any vertebrate. Adélie and chinstrap penguins advanced their breeding by around 10 days.

The changes could also intensify competition between species.

“Gentoos are a more temperate species and are already benefiting from the milder conditions that climate change is bringing to Antarctica,” Juarez said. “They’re already expanding their colonies throughout the peninsula and growing their numbers in colonies that were already established, while Adélies and chinstraps are both declining throughout the Antarctic peninsula.”

Gentoos’ ability to switch between krill and fish gives them a further advantage.

“With food, gentoos are foraging generalists,” Juarez said, adding that this makes them less vulnerable in years when krill is scarce.

Traditionally, staggered breeding times have helped the three species share space.

 “Part of the reason why we see the three species living together in the Antarctic peninsula is because of their traditionally staggered reproduction,” Juarez said.

But earlier breeding could increase competition for food, nesting sites and snow-free ground.

“We’ve already seen gentoos take nests that were previously occupied by Adélies or chinstraps.”

Scientists remain uncertain about the exact trigger for the shifts, though warmer temperatures, earlier ice breakup and changes in plankton blooms are all possible factors.

With penguins playing a crucial role in Antarctic food webs, researchers warn that further population declines could threaten the stability of the entire ecosystem.

By Sabina Mammadli