As regular CFZ-watchers will know, for some time Corinna has been doing a column for Animals & Men and a regular segment on On The Track... particularly about out-of-place birds and rare vagrants. There seem to be more and more bird stories from all over the world hitting the news these days so, to make room for them all - and to give them all equal and worthy coverage - she has set up this new blog to cover all things feathery and Fortean.

Friday, 10 June 2016

Do female birds mate with multiple males to protect their young?

Date: May 30, 2016
Source: KILDEN - information and news about gender research in Norway

Blue tit females mate with more than one male. Several possible blue tit fathers may then work together to stop predators from attacking their young, according to new research from the University of Bergen. Philosopher Claus Halberg believes this research challenges established ideas about the passive female.

"In many species, such as the blue tit, females often mate with multiple males. We've known this since the 1990s. The question has been why. For a long time it was thought it was to ensure that the offspring got the 'best' genes. But our studies indicate that it may have to do with completely different reasons," says Adele Mennerat.

Mennerat is a post-doctoral research fellow in the Department of Biology at the University of Bergen. She also teaches at the Centre for Women's and Gender Research.

Blue tits pair off in the winter. While only females build nests, they share the feeding task with the males when the young are born. But if the chicks are given a DNA test, it will often show that they have up to three or four different fathers. For the sake of simplicity, let's call these chicks that are not the offspring of the male feeding them, "extra-pair chicks."

"The main hypothesis has been that the fathers of the 'extra-pair chicks' had especially good genes and that this was why the female had mated with them. But around the year 2000, evolutionary biologists began to doubt whether this was the main explanation. Many researchers tried to show this was the case -- that is, there was a difference in genetic quality between the extra fathers and the feeding father -- but they found little evidence for this," explains Mennerat.

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