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Climate crisis pushes albatross ‘divorce’ rates higher – study | Birds

Climate crisis pushes albatross ‘divorce’ rates higher – study | Birds

Black-browed albatrosses in New Zealand.

Albatrosses, some of the world’s most loyally monogamous creatures, are “divorcing” more often – and researchers say global heating may be to blame.

A new Royal Society study has found that warming waters and climate change are driving black-browed albatross divorce rates higher. In general, 1-3% of those who choose a partner would decide to leave in search for better romantic pastures.

However, couples split up in years of unusually warm water temperatures. The study was done over 15 years and examined wild populations of 15,500 breeding couples in the Falkland islands.

For seabirds, warmer water means less fish, less food, and a harsher environment. Fewer chicks are born. The birds’ stress hormones increase. They are forced to hunt further afield.

The love lives of albatrosses, who are among the most loyal of all the animals, have been a long subject of scientific research. “There are all these things we think of as being super-duper human,” says Dr Graeme Elliot, principal science adviser at New Zealand’s department of conservation, who has been studying albatrosses in the country’s waters for three decades.

Birds are able to be anthropomorphized. They live for between 50-60 years and go through a long awkward teen phase where they learn to seduce their mate through dance. As they get older, they take many years-long trips far from home. They often mate for the rest of their lives and shout when greeting a partner who has been absent for a while.

However, they now share another rite that may sound familiar to young people: some are struggling to maintain relationships due to stress from the climate crisis and working longer hours to eat.

Black-browed albatrosses in New Zealand.
New Zealand: Black-browed albatrosses Photograph: Francesco Ventura

Francesco Ventura, a researcher at University of Lisbon, and co-author of the Royal Society Study, stated that researchers were surprised to discover that warmer waters were associated wit unusually high rates of albatross couple splitting up, even though there was no fish.

Ventura stated that Albatross divorce is usually caused by a reproductive failure. If a pair fails to produce a chick, there is a greater chance that they will split up. A lower food supply could result in more bird deaths. But the researchers were surprised to find that even when they accounted for that, higher water temperatures were having an extra effect – pushing up divorce rates even when reproduction was successful.

Ventura floated two possible reasons – one that warming waters were forcing the birds to hunt for longer and fly further. If birds do not return to their breeding season due to this, their partners could move on to find a new partner. Additionally, albatross stress hormones rise in warmer and harsher environments. Ventura suggested that the birds could feel that way and blame their partner.

​ “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 says.

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Research comes in many international languages albatross populations are in trouble. “Their numbers are plummeting,” Elliot. Elliot noticed that wandering albatrosses’ populations were dropping at a rate of 5-10% each year. They had been declining since 2005. The decrease in numbers is due to fewer prey, warmer seas, and increased encounters with tuna-line-fishing boats that accidentally catch and kill the birds.

Dropping population numbers were changing the birds’ mating patterns in other ways, Elliot said, with more homosexual couplings appearing. “We’re getting male-male pairs amongst the birds on Antipodes Island, which we haven’t had before,” he said. “A few percent of the boys are pairing up with another boy because they can’t find a female partner.”

The Royal Society study had looked at a population of black-browed albatrosses in the Falkland Islands, where numbers were still strong, and where divorce was not catastrophic, Ventura said – birds could find other partners. Ventura said that the same dynamics could be applied to other albatross population and could have a more devastating effect in areas with lower bird numbers. “If we’re talking about a population with a much lower number of breeding pairs, that disruption of a bond might definitely induce some disturbance in the regular breeding processes,” he said.

Now, Elliot hopes that some of the sympathies people have for albatrosses could motivate changes in behaviour, to address the environmental threats the birds are facing – particularly climate change, and tuna fishing. “We kind of need an international campaign to save these birds,” Elliot says. “If we don’t turn it around, they’ll go extinct.”

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