Divorce More Common Among Albatross Couples With Shy Men, Study Finds | MIT News

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The wandering albatross is the flagship bird of avian monogamy. The graceful glider is known to mate for life, associating with the same bird to breed, season after season, between long sea flights.

But on rare occasions, an albatross pair will “divorce” – a term birders use for cases where one mate leaves the pair for another mate while the other mate remains in the flock. Divorce rates vary widely across the avian world, and the divorce rate for wandering albatrosses is relatively low.

Nevertheless, the giant dinghies can separate. Scientists from MIT and the Woods Hole Oceanographic Institution (WHOI) have found that, at least for one particular population of wandering albatrosses, a couple’s divorce depends on one important factor: personality.

In a study published today in the journal Biology Letters, the team reports that an albatross couple’s chances of divorce are heavily influenced by the “boldness” of the male partner. The bolder and more aggressive the male, the more likely the pair is to stay together. The shyer the man, the more likely the couple will divorce.

The researchers say their study is the first to establish a link between personality and divorce in a wild animal species.

“We thought that bold men, being more aggressive, would be more likely to divorce because they would be more likely to take the risk of changing partners to improve future reproductive outcomes,” says the study’s lead author, Stephanie Jenouvrier, associate scientist and seabird specialist. ecologist at WHOI’s FLEDGE laboratory. “Instead, we find divorcers more timid because they are more likely to be forced into divorce by a more competitive intruder. We expect that personality may have an impact on divorce rates in many many species, but in different ways.

Lead author Ruijiao Sun, a graduate student in the joint MIT-WHOI program and MIT’s Department of Earth, Atmospheric, and Planetary Sciences, says this new evidence for a connection between personality and divorce in the wandering albatross could help scientists predict population resilience.

“The wandering albatross is a vulnerable species,” says Sun. “Understanding the effect of personality on divorce is important because it can help researchers predict consequences on population dynamics and implement conservation efforts.”

The co-authors of the study are Joanie Van de Walle from WHOI, Samantha Patrick from the University of Liverpool and Christophe Barbraud, Henri Weimerskirch and Karine Delord from CNRS-University of La Rochelle in France.

Repeatedly divorced

The new study focuses on a population of wandering albatrosses that regularly return to Possession Island in the southern Indian Ocean to breed. This population has been the subject of a long-term study dating back to the 1950s, in which researchers monitored the birds each breeding season and recorded pairings and breakups of individuals over the years.

This particular population is skewed towards more male individuals than females because the foraging grounds of female albatrosses overlap fishing vessels, where they are more likely to be accidentally caught in fishing lines as bycatch. .

In previous researchSun analyzed the data from this long-term study and found a curious pattern: People who got divorced were more likely to do so again and again.

“Next, we wanted to know what motivates divorce and why some people divorce more often,” says Jenouvrier. “In humans, you also see this pattern of repetitive divorce, linked to personality. And the wandering albatross is one of the few species for which we have both demographic and personality data.

This personality data comes from an ongoing study that began in 2008 and is led by co-author Patrick, which measured the personality of individuals among the same population of wandering albatrosses on Possession Island. In the study of animal behavior, personality is defined as a consistent difference in behavior displayed by an individual. Biologists primarily measure animal personality as a gradient between shy and bold, or less to more aggressive.

In Patrick’s study, the researchers measured the boldness of albatrosses by gauging a bird’s reaction to a human approaching its nest, from a distance of about 5 meters. A bird is given a score based on its reaction (a bird that does not respond scores a zero, being the most shy, while a bird that raises its head, and even stands up, may get a higher score, being the boldest).

Patrick has done several personality assessments of the same people over several years. Sun and Jenouvrier wondered: Could an individual’s personality have something to do with their chance of getting a divorce?

“We had seen this repeating divorce pattern and then spoke with Sam (Patrick) to see, could it be personality related?” Sun reminds. “We know that personality predicts divorce in humans, and it would be intuitive to link personality to divorce in wild populations.”

shy birds

In their new study, the team used data from demographic and personality studies to see if any patterns between the two emerged. They applied a statistical model to the two datasets, to test whether the personality of individuals in a pair of albatrosses affected that pair’s fate.

They found that for females, personality had little to do with bird divorce. But among men, the trend was clear: those identified as shy were more likely to divorce, while bolder men stayed with their partners.

“Divorce doesn’t happen very often,” says Jenouvrier. “But we found that the more shy a bird, the more likely it is to get divorced.”

But why? In their study, the team puts forward an explanation, which environmentalists call “forced divorce”. They point out that in this particular population of wandering albatrosses, males far outnumber females and are therefore more likely to compete for mates. Males who are already in a pair may therefore be faced with a third “intruder” – a male who is vying for a place in the pair.

“When there is a third intruder competing, shy birds might move away and give away their mates, where bolder individuals are aggressive and will guard their mate and secure their partnership,” says Sun. “That’s why more shy people may have higher divorce rates.”

The team plans to expand their work to examine how the personality of individuals can affect how the population as a whole changes and evolves.

“Now we’re talking about a connection between personality and divorce on an individual level,” Sun says. “But we want to understand the impact at the population level.”

This research was supported, in part, by the National Science Foundation.

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