With its spiky head plumage and intense red eyes, the southern rockhopper penguin (Eudyptes chrysocome, seen above) looks more like a slightly predatory guy at a college party than a committed monogamous partner. But these males mate for life, reuniting with the same female year after year during mating season. Despite their monogamous mating patterns, however, the birds really don’t spend much time together, according to a new study. Using GPS trackers mounted to the penguins’ legs, scientists monitored 16 birds from a colony in the Falkland Islands over the course of a mating season. The data show that males arrived at the nesting site approximately 6 days before their female counterparts and stayed about 6 days longer. However, the short mating season means the pairs are only united for about 20 to 30 days a year. And when they were separated, it was usually by a large distance: During the winter months, partners were separated by an average distance of about 600 km, and one pair was observed as far as 2500 km apart, the team reports online today in Biology Letters. Despite the large spatial segregation, their habitats were quite similar, ruling out the possibility that partners are spending the winter months apart because of sex-based differences in habitat or food preference. So why don’t the birds just stick together? So far it’s still a mystery, but the team speculates that if the birds arrived at and left the nesting site at the same time, they’d be much more likely to spend the winter together. But because the females show up late and leave early, the cost of finding one another after a week of dispersing through the open ocean might not be worth it—it’s easier to just meet back at the nesting site next year.
Science| DOI: 10.1126/science.aad1726