Albatrosses are fiercely loyal creatures: When they couple up, it’s usually for life. But in recent years, they’ve been splitting more often. Increasing water temperatures amid climate change may be to blame, according to a study published by the UK’s Royal Society.
These birds, which are mostly found in the southern hemisphere but have been occasionally spotted in the northeast, have a long and careful process for choosing mates. When they are only a few months old, each one travels on a solitary journey for a few years. All that alone time leads them to crave companionship, so as soon as they reach sexual maturity, they return to their nesting colonies to perform elaborate dances with prospective suitors.
Like a typical night out at a bar or nightclub, the birds begin by dancing in large crowds, but groups get gradually smaller. Eventually, the birds end up in pairs, and those relationships tend to last.
That’s not to say that albatrosses don’t have roving eyes. They do engage in “extra-pair copulation,” better known as cheating. Despite these affairs, they usually manage only nest with their main mates, returning year after year to the same nesting spots to breed with one another, and care for their young. Rates of “divorce” —wherein pairs stop nesting together — have averaged below 4 percent.
The new report, published in Proceedings B, the Royal Society’s biological research journal, ”found that ocean warming due to climate change appears to be messing with these harmonious relationships.”
For their analysis, the authors examined a wild population of 15,500 breeding albatross couples in the remote South Atlantic Falkland Islands over a 15-year period. By visiting the birds and also tracking them with GPS devices, the authors traced the birds’ mating patterns, looking to measure the frequency of divorce. They then compared these rates with data on nearby water temperatures.
In years where waters were cool, as few as 1 percent of albatross pairs headed to splitsville. But the researchers found that in years where water temperatures were unusually warm, instances of divorce rose dramatically, with up to 8 percent of couples breaking up.
There are a number of ways that difficult environmental conditions can ruin albatrosses’ relationships. For one, warmer waters can mean there are fewer fish around for the birds to eat. Some may be so malnourished that they’re not able to procreate, while others are likely prioritizing finding food over heading home to their sweethearts to breed.
Traveling on longer journeys to find nourishment can also make it more difficult for birds to sync up their mating schedules. Scarce food can also cause birds’ stress hormones to skyrocket, leaving them less interested in sex and more prone to grumpiness, which the scientists speculate may be pushing birds to separate even after mating successfully.
“The higher levels of stress might induce the female to ‘blame’ ... the partner, attributing her stress to a poor performance by the male and leaving him in favor of alternative mates,” Francesco Ventura, researcher at University of Lisbon and co-author of the Royal Society study, said.
The new study is the latest sign that the climate crisis is leaving seabirds in peril. Previous research has found that scarcer prey is threatening albatrosses’ reproductive success and making it harder for baby birds to survive. Fishing boats and trawls are also killing an increasing number of the birds. Some kinds of albatrosses are among the most endangered birds in the world. Without urgent action to stop ocean-warming greenhouse gas emissions, they could soon be gone for good.