Penguins adjust breeding season to climate change

Just 3°C more is enough to change the habits of penguins living in Antarctica, scientists from the University of Oxford show. Due to climate warming, these birds are starting to breed up to 24 days earlier, which may have serious consequences for species balance in the far South.

How were penguin habits studied?

A team of biologists from the University of Oxford and Oxford Brookes University was the first in the world to study the penguin breeding season on such a large scale. The results of the groundbreaking observation were published on 19 January this year in the journal Journal of Animal Ecology.

A total of 77 time-lapse cameras were placed around habitats on the Antarctic Peninsula and islands off the coast of Antarctica, precisely recording the behaviour of these exceptional birds. Scientists observed representatives of three species: Adélie penguins (Pygoscelis adeliae), gentoo penguins (Pygoscelis papua) and chinstrap penguins (Pygoscelis antarcticus). Each recorded image was accompanied by a measurement of air temperature.

The project was particularly interesting because images from the cameras were published for 10 years on the Penguins Watch website. Thanks to this, any nature enthusiast could take part in the study by tagging observed penguin breeding behaviours.

Penguins and climate change – a clear link

Higher temperatures mean there is less sea ice around Antarctica, which in turn triggers earlier phytoplankton blooms, the basis of the local food chain. However, earlier krill development can be a trap and attracts fishing trawlers that reduce the availability of penguin food.

As noted by the study leader, Ignacio Juarez Martinez: Temperature changes are happening so quickly that penguins may begin breeding when their food is not yet readily available. This can result in a lack of food for chicks in the first weeks of their lives and may pose a lethal threat to them.

Record pace of change raises concerns about species balance

Among the three observed species, gentoo penguins proved to be record holders in terms of changes in the breeding season. Over the course of 10 years, the average start of breeding shifted by 13 days (in some colonies even by 24). For the other two penguin species, the shift was about 10 days.

For comparison, it is worth citing the results of another study on bird breeding seasons: an observation of great tits in Europe. As reported by the Associated Press News portal, an acceleration of the breeding season by about two weeks was also observed there. However, these changes occurred over… 75 years, not a decade.

According to the authors of the study, climate change has its winners and losers. Scientists include gentoo penguins in the first group. Thanks to a varied diet that also includes fish, they cope better than other species with changing conditions. The presence of other penguins in a given area strongly depends on access to krill. This may cause gentoo penguin populations to displace other species from some habitats, disrupting the balance in Antarctica.

Another cause for concern is the disruption of the natural breeding calendar. Until now, Adélie penguins and chinstrap penguins began breeding much earlier than gentoo penguins. A change in these habits may lead to competition for nesting space, threatening breeding success.

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Source:

Juarez Martinez, I., Kacelnik, A., Jones, F. M., Hinke, J. T., Dunn, M. J., Raya Rey, A., Lynch, H. J., Owen, K., & Hart, T. (2026). Record phenological responses to climate change in three sympatric penguin species. Journal of Animal Ecology, 00, 1–15. https://doi.org/10.1111/1365-2656.70201