Julia is getting divorced
Another myth less about eternal love. The giant skuas (Catharacta skua) is a seabird that has been widely thought to form a lifelong relationship. But it seems that this romantic image is not quite the truth: 'divorces' are common keep an eye out for a better match. Paulo Catry and his colleagues from the University of Glasgow studied the largest colony of giant skuas in Europe (January issue of Animal Behaviour). About 2500 breeding pairs inhabit the island of Foula, which is part of the Shetland Islands north of Great Britain. Indeed, although many of the pairs happily raise little giant skuas in the same territory year after year, a certain level of infidelity and malicious abandonment is nonetheless evident. The divorce rate is currently six percent. Even if this is still small compared to the numbers from the statistics on human behavior - one can hardly speak of basically lifelong loy alty.
What can be the reason when a couple separates? A thesis has been advanced that the birds go their separate ways when they discover that they are mismatched as parents. In the case of giant skuas, however, the reasons for divorce seem to be much more bitter. And it's always the females who go in search of a better match.
It is often observed that the female birds make unauthorized visits to the territories of other males. They are looking for what, in human eyes, might not be a particularly romantic offer, a meal thrown up by the new suitor. If the quality of the meal was sufficiently appealing, the female will leave her old mate and move to the territory of the new male. So here the way to love is clearly through the stomach.
It may even happen that female invaders chase away the female of an existing pair in order to get the mate of their choice. Success with this strategy is relatively rare, but attempts at it are common.
Researchers claim that a female will be driven to divorce her mate if she values breeding success with a new mate. The lonely abandoned males rarely breed in the year after a divorce, the females almost always successfully. Although fewer chicks are usually raised in the early years of an avian marriage, the female concludes that the loss will be more than made up for in future years.
Leaving a partner does not seem to be related to age difference. Couples with a 10-year age difference are no more likely to break up than couples of the same age. The judgments must be based on the perceived "quality" of the males. Or should some male giant skuas tend to drink too much beer and talk about football all the time?
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