Wandering albatrosses have a large fanbase, especially among visitors to subantarctic islands. Because the largest seabirds in the world are not only graceful in the air, but also inspire people with their way of life. Basically, these seabirds are considered to be extremely monogamous and remain with their partners throughout their long lives. But a population of wandering albatrosses probably doesn’t want to know about that, as an international research team has found out.
On Possession Island, one of the islands of the sub-Antarctic Crozet Archipelago, those male wandering albatrosses that boldly and decisively approach a female dominate over their fellow males, and they have better luck even with females that are already in a relationship. They are also less likely to lose their relationship with their mate than the shy males who avoid confrontation. That’s the result of a study by Ruijiao Sun, a graduate student at the Massachusetts Institute of Technology MIT, who, under the direction of Stephanie Jenouvrier of the Woods Hole Oceanographic Institute WHOI, had studied wandering albatrosses on the island. “Divorce doesn’t happen often,” Stephanie Jenouvrier explains, “but we found that the shyer a bird is, the more likely they are to divorce.”
Previous long-term studies of the island’s wandering albatrosses had shown that the animals have very individual personalities with very different traits. Therefore, the question for Sun and Jenouvrier was whether the higher divorce rate observed earlier (compared to other subantarctic islands) could be attributed to the birds’ personalities. “We know that personality predicts divorce in human beings, and it would be intuitive to make the connection between personality and divorce in wild populations,” Ruijiao Sun explains. In a previous paper, Sun had discovered that not only was the divorce rate higher, but that animals that divorced did so repeatedly, similar to what is known to happen in humans, adds Stephanie Jenouvrier.
That’s why they compared personality traits, which has been studied since 2008 by the study’s co-author, Dr. Samantha Patrick of the University of Liverpool. The result of the study was quite clear: while in females personality has no influence on divorce behavior, in males those who appeared bold and confident were less affected by divorce than those males who retreated when approached and harassed by a second male.
The research team also found an explanation for the reasons for this behavior. Ile de la Possession is an island belonging to the French Crozet archipelago, located halfway between Madagascar and Antarctica. The resident migratory albatrosses are much more vulnerable to fishing bycatch than other locations, due to both legal and illegal fishing for Patagonian toothfish and other fish in the waters surrounding the archipelago. Because this fishing occurs in areas where female wandering albatrosses also travel, they get killed disproportionately high on fishing vessels’ longlines. This creates an imbalance between males and females on the island. Those males that lose their mate thus get into a kind of mating despair when the mate does not show up and he pushes his way to the next mates. There he tries to turn the female to his preferences and can be aggressive. When a shy male faces this situation, the mate is not defended and she then turns to the new one.
Since this particular behavior usually occurs before actual mating, the young birds are unlikely to be affected. But what impact this behavior has on the population as a whole is what Sun and Jenouvrier want to explore next. For the divorced males, the only hope is to find a new mate that has not yet been courted. But time is running out, as the number of wandering albatrosses is declining globally, despite conservation efforts.
Dr Michael Wenger, PolarJournal
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