The rise in divorce rates of monogamous albatrosses is being caused by climate change. As warmer waters cause males and females to travel farther for food, the rate of divorce will increase.
The conclusion of 15-year-old study by University of Lisbon researchers on black-browed albatrosses of Falklands is now known.
Normally, just 3.7 per cent of the birds split up from their chosen mate — a parting of the ways that occurs in the wake of a failed attempt at breeding offspring.
This figure can reach as high as 8% when the water temperature is elevated. Pairs may split even after having a successful breeding season.
Two possible reasons why warmer sea temperatures might be increasing the number of albatross divorces have been suggested by researchers.
The first is that males — forced to hunt for longer and fly further — are not returning to their breeding grounds in time in warmer years, and so the females move on.
Or, perhaps the birds are experiencing more stress from difficult circumstances and scarcity of food, which can lead to unsuccessful pairings being viewed negatively.
Female albatrosses might decide to change their partners next year in misguided hopes of easier breeding.

Climate change is increasing divorce rates in monogamous albatrosses, who are notoriously monogamous. Warming waters force males to travel farther for food. Image: The breeding couple
Francesco Ventura (University of Lisbon) and his associates carried out the study.
‘In many socially monogamous species, divorce is a strategy used to correct for sub-optimal partnerships and is informed by measures of previous breeding performance,’ the researchers wrote in their paper.
‘The environment affects the productivity and survival of populations, thus indirectly affecting divorce via changes in demographic rates.
‘However, whether environmental fluctuations directly modulate the prevalence of divorce in a population remains poorly understood.’
Since 2003, the researchers have been collecting data on the black-browed albatross population that breeds on New Island, in the Falklands, which is estimated to number some 15,500 bird pairs in total.
Five sub-colonies were chosen by the team to record the annual encounters of breeding birds and non-breeding birds in the study patches.
The tagging rings that were attached to the feet of each bird allowed them to be identified.
They also kept an eye on the fate of each chick and egg.
It was confirmed by the team that couples of albatross birds were more likely than not to divorce after a breeding success, and the birds choose to find new breeding partners during the next season.
Specifically, female albatrosses — who tend to initiate break-ups — were 5.4 times more likely to split with their partner if their eggs failed to hatch.
The team found, however, that albatross divorcing rates rose with the onset of warm sea temperature anomalies. This was true regardless of their previous breeding performances. It reached as high as 8% of all breeding pairs.
‘Environmentally driven divorce may therefore represent an overlooked consequence of global change,’ the researchers warned.

Normally, just 3.7 per cent of the birds split up from their chosen mate — a parting of the ways that occurs in the wake of a failed attempt at breeding offspring. Yet this figure rises to as high as 8 per cent when water temperatures were elevated — with pairs splitting even after a successful previous breeding season. A breeding pair of albatrosses with blackbrows

Since 2003, the researchers have been collecting data on the black-browed albatross population that breeds on New Island, in the Falklands — home to some 15,500 bird pairs
Although the Falkland Islands’ albatross population is not at risk, there are potential problems with smaller numbers in other parts of the world if temperatures rise.
Researchers warned that current climate changes could also affect other species, which are known to choose long-term partners.
‘We argue that investigating divorce adopting a temporal perspective may provide critical insight into the role of the environment on divorce in other socially monogamous avian and mammalian populations,’ the team concluded.
Proceedings of the Royal Society B published the full results of the study.