One of the most famously monogamous species of birds may be driven to “divorce” their partners at higher rates as a result of a warming planet, a new study found.
Black-browed albatrosses have the reputation of mating for life and usually stick with one partner after pairing off. Usually, only 1% to 3% of albatross pairs split up and find new mates, according to The Guardian.
But that rose to as much as 8% during years of unusually warm water temperatures, according to researchers who analyzed data involving more than 15,000 albatross pairs in the Falkland Islands over a 15-year period. The study was published in the Royal Society journal this week.
Scientists have long known that albatross pairs may divorce, typically involving the female finding a new mate, if they had an unsuccessful breeding season. But researchers found that in unusually warm years, breakup rates rose even among pairs that had successfully reproduced.
So why might warmer waters have this kind of effect? For one thing, warmer waters mean that phytoplankton, organisms that form the foundation of the marine food chain, are less plentiful. As Scientific American noted, the scarcity of phytoplankton has cascading effects up the food chain and, in this case, means that albatrosses must fly farther and work harder to find enough food.
In some cases, birds may simply have traveled farther afield and not returned in time for breeding season, leading their partners to find a new mate, University of Lisbon researcher and study co-author Francesco Ventura told The Guardian.
Ventura also said harsher temperatures and having to work harder to eat raises stress levels in the birds overall, and it’s possible that the birds may more or less blame their partner for their unhappiness.
“We propose this partner-blaming hypothesis ― with which a stressed female might feel this physiological stress, and attribute these higher stress levels to a poor performance of the male,” he said.
Earlier this month, a different study was published that documented another way that human-caused climate change seems to be affecting birds. That study found that birds in the Amazon rainforest are getting smaller in size as temperatures get hotter.