Image: 'Bold' great tit bird
Samantha Patrick
'Bold’ great tit (a type of bird) males are less faithful, fathering more young outside their nest, but their boldness had a cost: their mates were more likely to cheat as well.
updated 11/29/2011 8:21:39 PM ET 2011-11-30T01:21:39

Males that stray from the nest for adulterous adventures may leave an opening for their mates to cheat, new research on great tit birds suggests.

While these absentee males end up with more adopted chicks from the female mate's flings, they also leave their own offspring in other nests. On average, the "bold" males have the same number of chicks as males who stay home.

"If a male has a bold personality score, he has more extra-pair young — more of his paternity will come from outside of his own nest than from within," study researcher Samantha Patrick, of the Center for Biological Studies Chizé, in France, told LiveScience. "Because the male is absent, his female is unprotected."

Opportunistically monogamous
Great tit birds are socially monogamous, which means they stick with one partner for life. Based on previous work, though, the researchers knew that the bolder, more adventurous of the species tend to cheat on their partner. The researchers weren't sure if this actually gave the bold males more offspring, since it lets their mates cheat as well.

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For three years, the researchers studied a wild group of great tits (Parus major), a small common European and Asian bird, nesting in boxes near Oxford University. The researchers captured wild birds from the area and studied how they reacted to a new environment in the lab. The "bold" birds were more adventurous and inquisitive in the new environment, exploring the nooks and flying from perch to perch.

The researchers took samples of the birds' DNA and released them into the wild. The researchers then used that DNA information to determine which chicks came from which fathers and how this correlated with the dads' boldness scores.

About 13 percent of the chicks were offspring from extra-pair mating by the males, with about half of the nests holding offspring from "adulterous affairs." The males scoring highest on boldness the most likely to have extra-pair chicks. But because these cheating males spent more time away from the nest, their female mates had more chicks from other males as well. In the end, wandering males had no more offspring than their stay-at-home brethren.

"Males that were very bold, that explored very quickly, they were much less faithful to their mate, but they also had less paternity in their nests," Patrick said. "What it showed was that your personality didn't predict your fitness, how many young you had, but it predicted the mating strategy though which you had those young."

Kees van Oers, a researcher at the Netherlands Institute of Ecology, told LiveScience in an email that the study is "very valuable" because, "the role of personality in mating decisions and extra-pair paternity is not well studied." There are slight differences between this study and a previous one by his own group possibly because the study group of birds was larger and enabled the researchers to look closely at the associations between birds and their offspring, or because of the different locations used (his study was in the Netherlands).

Benefits of being bold
Not all of the bold males were as successful cheaters as others, with some fathering one chick outside the nest while others may have fathered four or five. The researchers suggest the bird's surroundings could impact their success: If a bold male is surrounded by shy males, he may be more successful at fathering more offspring with females that aren't his mate.

"It might be a byproduct of their personalities, of their level of exploration, bold birds may be more active, they may be encountering other females, and have the opportunity," Patrick said. "Shy birds may explore less and encounter fewer other birds, and therefore be more faithful to their mate."

Tough environmental conditions may also give some bold birds a leg up, since bold birds range farther in search of food and tend to be more dominant in territorial squabbles. The result is more success at surviving — and thus, passing on their genes.

The study is published Nov. 30 in the journal Proceedings of the Royal Society B: Biological Sciences.

You can follow LiveScience staff writer Jennifer Welsh on Twitter @microbelover. Follow LiveScience for the latest in science news and discoveries on Twitter@livescience  and on Facebook.

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Explainer: 10 peeks at sex in the wild

  • Image: scroll fragment
    Jerome Maison  /  AP file / Warner Independent Pictures

    Emperor penguins endure some the harshest conditions on the planet — the Antarctic winter — to satisfy their primal urge for sex. The annual ritual begins with a days-long, up to 75-mile slog to their inshore breeding grounds. Once there, an elaborate courtship of calls and poses reunites old mates and enables young lovers to form lasting bonds.

    Copulation itself occurs under the cover of the dark of the polar night. Then the true sign of their devotion begins: Males huddle together to incubate the eggs as the females waddle back out to sea to feast, fattening up to provide for their newly hatched young. Once she returns, males depart in the first of a tradeoff that may, eventually, allow for healthy offspring.

    Click on the "Next" label for nine more peeps at sex in the wild.

    - John Roach, contributor

  • Captive pandas require help to get it on

    Image: Pandas
    Wichai Taprieu  /  AP file

    In the wild, biologists say pandas get it on without too much of a hitch. But since the wild population in China's mountain forests hovers around just 1,600, there's a push to boost the panda population in zoos around the world. And that's where the problems lie. Many pandas lack interest in their arranged mates and some inexperienced males who give it the old college try fail to engage the proper body part. As an aid, some zoo keepers attempt to arouse the bears and teach them appropriate technique with specially made DVDs, a.k.a. panda porn. When that fails — and it often does — artificial insemination is considered a last resort. These tricks combined with a better understanding of what makes the panda libido tick are beginning to pay off. The captive population has boomed in recent years.

  • Male macaques groom for sex

    Image: Japanese Macaque monkeys
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    Male macaques groom females in exchange for sex, according to a study that examined the market underpinnings of monkey sex. According to the research, based on 20-months of observation in an Indonesian nature reserve, a female is three times more likely to mate with a male if he grooms her first. Supply and demand also comes into play: Males spend more time grooming when competition for female attention is greater. Scientists refer to this practice as a biological market.

  • Male antelopes play hard to get

    Image: Antelopes
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    For highly-desired male topi antelopes in Africa, the frenzied six-week-long mating season is exhausting. Any given female is receptive for about a day, thus she wants to mate as many times as possible, especially with the fittest males. This creates intense competition for high quality antelope sperm, allowing those that possess it to be picky. A study of the phenomenon found the choosy males deliberately select the least mated females and fend off aggressive females they've already mated with. The aggressive female in the center of this image is attacking the male on the left as another female eyes the scene.

  • Sumatran rhinos tussle before they tango

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    Tom Uhlman  /  AP

    Mating for the typically solitary and territorial Sumatran rhinoceros is a drawn-out affair. Studies of the critically endangered species in captivity show that when a female becomes receptive to a male's approach, she'll exhibit increased urine spraying, tail raising and swinging, and vocalizations. Foreplay includes head and genital butting, which can be a bit too much when a female isn't quite ready to tango with a young and aggressive male. But when the tussle is successful, a male will mount, often riding his mate for up to an hour. The image here shows the results of a successful mating at the Cincinnati Zoo. Such captive breeding efforts are a silver lining for conservationists hoping to keep the Sumatran rhino alive — just 300 are thought to remain in the wild.

  • Burliest walrus bulls get the harem

    Image: Walrus
    Liz Labunski  /  AP

    With a cacophony of clicks, clacks, whistles, and bellows, male walruses swim around the chilly Arctic waters vying for the attention of ice-bound females. Males will also fight off other males that get too close, sending the loser packing. Once the fussing and fighting is done, female harems surround the burliest males in the water for an underwater romp. Though scientists know little about what actually happens under the cover of the waves, they do know walruses are endowed with the mammal world's largest penis bone, called a baculum, which extends up to 30 inches.

  • Dolphin mating is brief, but bountiful

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    For playful dolphins, mating seems just like another carefree and pleasurable way to pass away the day. Along with some typical male posturing for access to females, there's plenty of chasing, rubbing, nuzzling and stroking that constitutes as foreplay. The belly-to-belly copulation act itself lasts less than a minute, though is often repeated several times over the course of an hour.

  • Virgin female spiders risk all for a big mate

    Image: archaeological site in Masada

    For some male spiders, sex is the ultimate sacrifice: females eat them as part of the reproductive ritual. But among the East African blood-gorging jumping spider Evarcah culicivora, shown here, males possess the coital-infused cannibalistic urge. Nevertheless, female virgins opt to be deflowered by bigger males before settling in with a small guy for the long haul. Scientists suspect females gamble with their fate once in hopes of producing larger, fitter offspring, but decide not to double down after the flirtation with danger.

  • Sappy sex for beetles of all sizes

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    As this picture shows, Japanese sap beetles come in big, medium, and small sizes. Generally, in the beetle world, mating success is only bestowed on males with the biggest bodies because they can beat out the competition with brute force. Big sap beetles successfully employ this strategy, but when they do, the medium guys take to the air with their extra long wings and survey for sites where big males are absent. But the little guys have the biggest testicles. This allows them to hang with the big guys and sneak sex behind their backs. Since the little beetles have such big testes, they produce more competitive sperm, upping their chances at siring offspring when they get a shot.

  • Cycads have 'hot' plant sex

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    Hot sex has ancient roots. The males in a group of plants called cycads, which have been around for at least 250 million years, get all hot and bothered as a means to compel pollen-covered insects deep in their cones to flee forth and find a female to pollinate, according to scientists. The plants begin the process by emitting a fragrance that lures little insects called thrips into their cones. After a few hours of the thrips feasting and rolling around in there, the cycads heat up as much as 25 degrees Fahrenheit, which turns their sweet smelling fragrance into a stench. The thrips flee, some landing on benign-smelling female cycads and thus completing the pollination cycle.


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