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TORONTO (Reuters) - It's not all love in the avian world, where divorce, child abandonment and marrying up are part of everyday life.
"The Bird Detective," to be published in Canada this week, dispels the love-bird myth that birds pair up for life, and paints a picture instead that includes adultery and the pursuit of comfort.
"In terms of top 10 myths about birds, the permanent pair bonds that we think about, that does occur for some birds, but for most of the little songbirds that we studied, no," said the book's author, Bridget Stutchbury, a biology professor at York University in Toronto.
The book draws on 20 years of research from radio tracking and DNA testing and shows male Acadian flycatchers fertilizing females far away from their home nests, and female blue headed vireos premeditating divorce by checking out new mates before they abandon their young.
"The main discovery is that so many birds do divorce for what humans would describe as selfish reasons," Stutchbury said, noting that females may seek out males that are more colorful and better singers, or look to "step up in the world" and move to areas that are safer and have more food.
"Females are looking for the highest quality male so that their own offspring will be high quality," she said.
Stutchbury, who has studied dozens of songbird species in Canada, the United States and Panama, said shorter summers may drive females to leave their nests before their young are fully fledged so they can quickly find new mates and lay more eggs, That leaves the males to feed the hungry chicks on their own.
Males can triple or quadruple their reproductive success by fertilizing neighboring females, but only "mates" care for the young, and some are none the wiser.
"They can't tell when the egg hatches whether it's theirs or not," she said. "They have no way to know."
Divorce is surprisingly common among birds, and most live with one partner for only a few months or years. Divorce rates range from 99 percent in the greater flamingo to zero in the wandering albatross.
The book, published by HarperCollins, will be released on April 13 in Canada and at the end of May in the United States.
Reporting by Claire Sibonney, editing by Peter Galloway