Biologists revealed the effects of "divorces" among little penguins.

Phillip Island, located 125 kilometers southeast of Melbourne, is considered the largest settlement of little penguins, with an estimated population of around 37,000. Millions of tourists visit this destination each year to explore its natural parks and witness the "penguin parade" — a distinctive "march" that the birds perform as they emerge from the ocean after sunset and make their way along the beach in groups to their burrows in the sandy slopes.

Biologists from Monash University (Australia), in collaboration with colleagues from Germany and New Zealand, monitored the behavior of little penguins over 13 breeding seasons (from August to February between 2000 and 2012) at one of the sites in their mega-colony. The results of the study were published in an article recently released in the journal Ecology and Evolution.

Researchers know that members of the species Eudyptula minor live in pairs and can remain faithful to each other for extended periods, sometimes for life. However, observations on Phillip Island challenged the common belief in their monogamy.

It turned out that partner switching is not uncommon among little penguins: during the study period, biologists recorded nearly 250 "divorces" among approximately a thousand pairs they monitored. In a comment on the press release, co-author of the study Professor Richard Reina (Richard Reina) noted that penguins often have "flings" on the side.

As the scientists established, various factors influenced separations, with the most common being a low number of chicks in the brood and stress from environmental conditions that undermined the stability of the pairs.

The researchers found that "divorces" and entering into new "alliances" correlated with lower reproductive success for the colony overall. When biologists compared this factor with others, including the behavioral traits of the birds, the time spent foraging, and ecological conditions, the frequency of "divorces" emerged as the most reliable predictor of the reproductive success of the penguin colony. When more birds stayed with their partners from the previous breeding season, reproductive success was higher.

Considering the findings, the researchers concluded that monitoring the frequency of "divorces" could serve as a non-invasive tool for tracking reproductive trends in seabirds, particularly in populations living in variable external conditions. Studying and understanding this dynamic is crucial for the conservation of little penguins and other feathered inhabitants of Phillip Island.