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Climate change could cause more animals to get divorced
Climate change could lead to an increase in break-ups as it puts pressure on the animal kingdom.
Researchers have found that black-browed albatrosses are more likely to divorce in years when sea temperatures were significantly warmer than average, with the possibility many other species could be affected in the same way.
It's said that birds of a feather stick together. But with global temperatures rising, this adage starts to become unstuck.
A study published in Proceedings B found that black-browed albatrosses were more likely to split up as sea temperatures rose. The birds, which normally stick with their partner year after year, were especially likely to divorce their partner if they failed to breed successfully during the year.
The paper warns that these behavioural changes could represent 'an overlooked consequence of global change, with repercussions for demography and population dynamics.'
The long-term study, using almost two decades worth of data from the Falkland Islands, was conducted by an international team of researchers.
Black-browed albatross can cover huge distances when looking for food. Image © pixuberant/Shutterstock
Love you and leave you
The black-browed albatross lives in the southern hemisphere, where they soar across the open ocean before returning each year to islands such as the Falklands to breed. They eat a variety of seafood, including krill and squid, as well as scavenging foods including other birds.
Their hunt for food can take them on short trips around their breeding sites or on longer journeys that cover thousands of miles to destinations as far away as Antarctica and Angola.
After around a decade away from home, the albatrosses return to their breeding grounds to mate and lay eggs. About 70% of the world's black-browed albatrosses are found on the Falkland Islands, where they number around 500,000 individuals.
Raising an albatross chick is no easy feat for the parents. The egg is incubated for about 10 weeks, before the chick is raised for a further 17 weeks.
To increase their chances of success albatrosses are socially monogamous. Pairs that stay together are better co-ordinated during breeding and chick care, in addition to wasting less energy each year as they don't need to search for new mates.
On the other hand, divorce offers an opportunity to find a better partner for the birds. A failure to breed has previously been found to drive break-ups among albatross pairs, as there is chance that a new partner may improve reproductive success.
Scientists have also found that reproductive success is linked to temperature in albatrosses. Black-browed albatrosses have lower survival and lower breeding success when exposed to warmer than normal temperatures, potentially putting greater strain on their pair bonds.
To investigate how a changing climate might affect the birds, scientists used data gathered from around 31,000 black-browed albatrosses from New Island in the Falklands. From 2003 onwards, five patches of the breeding colony were studied with each encounter between breeding birds recorded.
This allowed the researchers to build up a comprehensive picture of how the birds were being affected by temperature anomalies over the following 15 years.
Black-browed albatross females were more successful when looking for a new partner. Image © Giedriius/Shutterstock
It's not me, it's CO2
The researchers found that when temperatures differed from normal, the divorce rate in albatrosses increased. The highest temperature anomaly studied, which took place in 2017, saw divorces more than double from an average of 3.7% to 7.7%.
The birds that were mostly affected by the divorces were those who did not attempt to breed, or failed to breed successfully. Only 8% of males retained a mate when breeding was not attempted, compared to 11% of females.
When finding a new partner, females were much more likely to be successful, as 59% of females who switched partners after failing to breed with their current one went on to successfully raise a chick.
Males had substantially less success, as only 45% managed to breed successfully after swapping mates.
This is likely due to competition between males for female black-browed albatrosses. It is thought that, after being abandoned by an ex, the lower quality males are less likely to find a new mate as the females are looking for more proven males.
The reason for the rise in break-ups is likely due to the increased stress temperature anomalies put on the albatrosses and their environment. Prey such as krill can't tolerate increased temperatures, leaving less food available for the birds to eat.
Stress hormones such as corticosterone may build up as a result of these environmental stresses. Coupled with failed breeding, this may cause a breaking point for the albatross pair, leading to divorce.
While the researchers' study focuses solely on the black-browed albatross, they believe that other socially monogamous species, which includes 90% of birds as well as mammals such as wolves, otters and bats, could be similarly affected by rising temperatures.
With the world currently on track for 2.4⁰C of warming if countries do not improve their climate targets, there may be plenty of love lost in the animal kingdom.
