Feeling the heat: the susceptibility of African Penguins to hot weather events and climate change

The African Penguin was classified as endangered by the IUCN in 2010. Among the threats facing this species is breeding failure due to heat stress. Historically, most African Penguins bred in guano burrows, providing buffered... [ view full abstract ]

The African Penguin was classified as endangered by the IUCN in 2010. Among the threats facing this species is breeding failure due to heat stress. Historically, most African Penguins bred in guano burrows, providing buffered microclimates and shelter from predators. Guano scraping led to habitat loss, an issue that exacerbates heat stress. Without a burrow’s protection, adults may leave their nests to cool down in the sea. This is often fatal for broods in surface nests due to predation and exposure. Climate change is increasing extreme weather, worsening the situation. Previous studies indicate that artificial nests can reduce impacts, but it was not understood if they could fully replace natural burrows. This study sought to determine the temperature when heat stress begins in African Penguins, understand behavioral responses to temperature, evaluate artificial nests’ effectiveness, and investigate how climate change affects penguins. Laboratory experiments showed that penguins could not cope with ambient temperatures above 28.5°C, almost 2°C lower than similar species, suggesting that African Penguins are particularly sensitive to climate change. Field studies using penguin models showed that heat stress may occur more often and at lower temperatures than anticipated. Artificial nests experienced high summer temperatures, above penguins’ heat stress point. Sun exposure increased temperature in all artificial nest types, but did not significantly affect natural burrows, indicating that artificial burrows do not adequately protect penguins from heat stress. Our analyses provide tools to predict how African Penguins may be affected by future climate change, limiting impacts by directing management actions.