A new albatross around the neck of bird populations? Warming sea temperatures are linked to an increase in "divorces" among albatrosses, according to a new study.
The research, published last week by New Zealand's Royal Society, found an increase in the probability of divorce among albatrosses, which usually mate for life, during years with warmer sea surface temperatures.
The research examined 15,500 breeding pairs of black-browed albatrosses on New Island in the Falklands over 15 years. Francesco Ventura of the University of Lisbon, an author of the research, said it shows a "direct link between the increase in sea surface temperatures and the increase in the probability of divorce."
Researchers found that the average divorce rate among the birds was 3.7%. But the divorce rates increased in years when the sea surface temperatures were warmer, rising to 7.7% in 2017.
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Ventura explained that divorce among albatrosses doesn't look like "a female calling for a lawyer and standing up and leaving the male on the nest." Instead, it is mainly caused by an inability to reproduce.
"Within our study colony, we knew exactly the identity of every single breeding bird and the fate of their reproductive attempt," Ventura said. "We were able to monitor the establishment of the pairs and investigate whether in the following breeding season both members of the pair survived and if at least one of them mated with another individual. That's how we define divorce."
The research accounted for previous breeding successes and failures among the birds, in addition to other factors. But Ventura said that alone couldn't explain the rise in divorce rates.
Instead, he explained that lower sea surface temperatures indicate waters with more food, while warmer waters "are more indicative of resource-poor conditions."
Therefore, when sea surface temperatures were warmer, the albatrosses had to struggle to find food at sea and search over a greater area.
That has two major effects on the albatross populations, Ventura said. First, the birds had to spend more time fueling up under the conditions, which meant they returned to their breeding colonies later, possibly introducing "an asynchrony between the two members of the pair."
Second, less plentiful food could "induce the females to be more stressed," Ventura said.
"So there is this higher physiological stress levels," he said, adding that some female albatrosses, which usually initiate divorces, "might interpret this higher stress as a poor performance by the partner and therefore decide to go for an alternative mate."
Ventura emphasized that the divorce rates among the albatrosses cited in the study are not a signal that their immediate population will plummet in the coming years. But other research has found that populations of the seabirds around the world "are collapsing."
This article originally appeared on USA TODAY: New Zealand bird study: Climate change could drive albatross divorce