“We show for the first time in a wild animal species a link between personality and divorce”explained to AFP Ruijiao Sun, first author of the study published in the Biology Letters of the British Royal Society. Diomedea Exulans, the great screaming albatross, is nevertheless a model of loyalty. Divorce is here “very rare”, with a rate of about 13% in the population studied by the ecologist, who is a doctoral student at the American Woods Hole Institute of Oceanography. If 90% of birds are monogamous, sailors are all without exception. But life as a couple is not smooth, even for the latter.
an albatross “shy” is up to twice as likely to divorce as an albatross “bold”
Studies have identified a divorce regime “adaptive”, in specialist language, that is to say motivated by the eternal imperative of reproduction. For instance, “if a bird finds that its chances of breeding are too low with a specific partner, it may look for another”, explains Ruijiao Sun. One study has spotted such behavior in the black-browed albatross.
Nothing like it here. On the other hand, the personality of the individual, more or less shy, “is one of the predictors of divorce”, explains marine biologist Stéphanie Jenouvrier, co-author of the study, to AFP. In this case, an albatross “shy” is up to twice as likely to divorce as an albatross “bold”.
To verify this, and explain it, the researchers drew on a database unique in the world, established by the Center for Biological Studies of Chizé, – which depends on the University of La Rochelle -, and the Polar Institute French Paul-Emile Victor.
Since 1959, their members have been recording the tribulations of a colony of great albatrosses established on Possession Island, in the icy waters of the Crozet Archipelago, one of the French Southern and Antarctic Lands. “We ring them with a number, and each year we draw a map with the location of their nest, they are not shy and by approaching slowly we can make many observations”says Stéphanie Jenouvrier, who worked for a long time for the center of Chizé.
“Some are very bold, some very shy, and most are in between”
Researchers can thus “reconstruct the whole history of these birds”, from their birth until their disappearance, she explains. Because Diomedea Exulans, which can live up to 50 years, has its habits. Once in a couple, it reproduces “every two years, because he needs a year to raise his only cub, before taking a year off, but separately, before the couple get together again”, explains Ruijiao Sun.
And this is where things get complicated. Males and females will spend months gliding, thanks to their wings with a span exceeding three meters, over several hundred kilometers a day, above the waters of the southern Indian Ocean. But in distinct areas, the males further south than the females, who seek sustenance in waters more frequented by trawlers using trolling lines. And there, “if the albatross tries to catch the lure, it sinks”explains Stéphanie Jenouvrier.
As a result, the population of great albatrosses is predominantly male, with a certain number of widowers obviously not intending to stay that way for too long. This is where the personality factor comes in. The researchers measured that of almost 2,000 individuals, over ten years, with a scale of reaction to the approach of a human up to five meters. More “bold”which ignores the intruder, up to the most “shy”which abandons the nest, which is very rare.
“Some are very bold, some very shy, and most are in between”, according to Ruijiao Sun. By cross-referencing these measures with those of the divorce rate, the researchers concluded that “Shy males divorce more than bold males”. A shy male in a relationship will prefer to spin the English way rather than confront a widower in need of the company of the opposite sex.
However, the personality of the protagonists does not explain everything. “Other factors are at work, remarks Stéphanie Jenouvrier, individuals who are in a long-term relationship are less likely to divorce than young couples”…