King Penguins Thrive in Warming Climate: A Glimpse into Their Uncertain Future

King penguins (Aptenodytes patagonicus) are thriving in the changing subantarctic climate. As temperatures rise, the survival rates of chicks reaching adulthood are also on the rise. While these penguins appear to be benefiting from climate change, researchers caution that they may eventually face challenges in accessing essential food sources.

In 2023, king penguin chicks on French Possession Island began hatching approximately 19 days earlier than in 2000. With a longer breeding season, the survival rate of chicks has increased to an average of 62%, compared to 44% in 2000, as reported by Gael Bardon from the Monaco Science Center and colleagues.

“King penguins are showing rapid changes that seem positive in the short term, but the long-term effects are still uncertain,” said Burdon.

Each summer, a pair of king penguins, easily recognized by their bright yellow-orange neck feathers, tend to a single egg, which hatches into a fluffy brown chick about two months later. After laying eggs, the parents leave the chicks on the island and swim hundreds of kilometers south to the polar front, where warm and cold currents create a nutrient-rich environment for plankton growth. The penguins catch small lanternfish that feed on this plankton and return to nourish their young.

Warmer waters may boost lanternfish populations. The study suggests that the early breeding of king penguins correlates with rising sea surface temperatures and decreasing plankton concentrations, indicating potential increases in lanternfish availability.

Burdon explained that this early breeding gives chicks more time to feed and gain weight before the challenging winter months, thus reducing the risk of starvation.

Although the Possession Island population appears stable due to improved chick survival, there may be penguins migrating to other islands, leading to population growth in new colonies.

Team members emphasize that the king penguin’s shift to early breeding is occurring faster than that of most polar species, serving as a “wake-up call” regarding environmental changes. Celine le Bohec from the Monaco Science Center shared these insights.

In recent years, abnormal warmth has caused the polar front to shift south, compelling king penguins to travel farther for food, resulting in declining chick survival and potential population decreases on Possession Island. Without islands beyond Possession Island for migration, the penguins are forced to expand their foraging areas. A study indicated that this population could diminish in the coming decades if the polar front continues to shift southward gradually. Research also suggests compromising food availability could be a critical issue.

“Rapid changes that extend the breeding cycle are favorable, but food availability on the polar frontier may collapse if colonies distance themselves too far,” cautions Le Bohec. “We risk reaching a tipping point.”

On the optimistic side, some researchers like Lewis Halsey, a professor at the University of Roehampton, UK, noted the resilience of penguins on Possession Island after the 2004 mini-tsunami. He highlighted that penguins also consume other nearby foods, such as squid, suggesting that while populations may decline, extinction is unlikely. “They demonstrate remarkable flexibility, indicating that a collapse is improbable.”

Scientists had hoped that the king penguin’s reproductive stability would hold as they adapted to climate changes, and the actual improvement in reproduction is a promising sign, according to Tom Hart from Oxford Brookes University, UK.

“This is encouraging news. Although conditions can change, king penguins are currently outperforming many of their counterparts in overall penguin populations, which are generally declining,” he remarked. “This is a rare success story.”

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