Penguins are breaking up more often – is this a threat to their population?

Penguins have long been considered a symbol of loyalty – these adorable birds, with their characteristic black-and-white plumage, are associated with lifelong bonds. It is widely believed that once a penguin finds a mate, it stays with them forever, raising offspring together and sharing the challenges of daily life. But does this romantic vision reflect reality? Research conducted on Phillip Island sheds new light on the matter. It turns out that breakups among penguins are not uncommon, and their consequences can significantly impact the future of entire colonies.

More penguin divorces

For over a decade, scientists on Phillip Island have closely observed the lives of little penguins. This picturesque island, located off Australia’s southern coast, is home to one of the largest colonies of these birds, known as the Penguin Parade, where thousands of individuals return each year to build nests and raise their young.

The research findings were clear: in seasons when more pairs stayed together, reproductive success – the number of hatched eggs and chicks that reached the fledgling stage – was significantly higher. Stable relationships led to more healthy young, ready to face life independently. Conversely, in years when the divorce rate increased, the situation became more challenging – the number of surviving chicks dropped, sometimes by as much as half compared to more successful breeding seasons.

Why do penguins break up?

What drives penguins to end their relationships? The answer lies in reproductive success. Research from Phillip Island indicates that the key factor is how well a pair fared in the previous breeding season. If their eggs hatched and the chicks successfully fledged and became independent, the partners usually remained together. Stability brought benefits – such pairs returned to their nests the following season, prepared for further success. However, failure – the loss of eggs or the death of chicks – often led to a breakup.

In such cases, one or both partners would begin searching for a new mate, hoping for better results in the future. From an individual bird’s perspective, this is understandable – every penguin strives to pass on its genes to the next generation, and an unsuccessful breeding season suggests that the current partnership might not be effective. However, for the entire colony, this strategy carries risks.

When too many pairs separate, fewer young reach adulthood, weakening the population. Additionally, environmental changes complicate matters – reduced food availability and harsher conditions increase pressure on pairs. Longer foraging trips are beneficial during the egg incubation period, but once the chicks hatch, they require frequent and rapid food deliveries. This delicate balance can easily be disrupted.

How do penguin breakups affect the population?

When pairs break up, not only do the individuals suffer, but the entire colony is affected. Research from Phillip Island shows that in seasons with a high divorce rate – sometimes reaching one-third of all pairs – fewer chicks reach adulthood. Experienced pairs that have worked together for years function like a well-coordinated team: one partner ventures out to sea to gather food, while the other guards the nest and cares for the young. This harmony translates into better outcomes – more eggs hatch, and more chicks survive. Newly formed pairs often struggle to achieve the same level of synchronization, which negatively affects chick survival.

Moreover, breakups delay the breeding season – finding a new partner takes time, causing chicks to be born later, often under less favorable conditions. If additional challenges arise at sea, such as limited fish availability, the situation becomes even more difficult. Research indicates that social stability is crucial for the survival and proper development of penguin colonies.