Around one in three clutches of eggs are abandoned in this way, making it a puzzling example of childrearing where both parents improve their reproductive success by abandoning the nest.
Males and females can mate with up to seven different partners in any one breeding season and frequently vary their attitude to childcare between different clutches.
Over the course of a breeding season more than half of all clutches are cared for by the female, with up to a fifth cared for by the male. The rest, roughly a third, are abandoned by both.
In an intensive battle of the sexes, male penduline tits often flee the nest before egg-laying is complete, whilst females sometimes hide their eggs from the males so she can leave before he notices how many eggs have been laid.
When this happens, males left caring for the eggs frequently flee the nest. Penduline tits can be found throughout most of central and southern Europe.
“If you are a penduline tit your perfect partner is one that is happy to stay home and look after the kids, whilst you go off and find a new partner,” said Dr Tamas Székely from the University of Bath (UK) who worked with colleagues from Eötvös University (Hungary) and University of Groningen (Netherlands).
“But whilst this is great for you, for your partner it is not so good. They end up having to stick around and rear the kids, which means they miss out on the opportunity to have more chicks themselves. It also increase their risk of being taken by predators while incubating the eggs or feeding the young.
“What is unusual about the penduline tit breeding system is that in one in three cases both males and females are willing to abandon the nest, even though the clutch will perish as a result. This could be said to be reminiscent of Hollywood life-styles with plenty of mating opportunities that may lead to neglect for the family at home.
“We have shown that over the course of the breeding season desertion enables the parents to produce a greater number of offspring, improving their reproductive success over those more willing to stay home. Interestingly, however, the sexes play the same strategy; whatever is good for the male is harmful for his female, and vice versa.
“Neither the males nor females are saints.”
Responsibilities for childcare vary enormously throughout the bird kingdom. Usually both parents care for the young although the female takes the bulk of care. In a score of species, such as in phalaropes and lily-trotters, males do all of the childrearing.
“As far as we know this willingness for both sexes to abandon the nest for the sake of new mates is unique,” said Dr Székely from the University’s Department of Biology & Biochemistry.
“Our findings reveal an intensive conflict between males and females over care that has affected the behavioural evolution of this species.”
Source: University of Bath
Related stories:
Male bird at Smithsonian's National Zoo has special reason to celebrate Father's Day
How will the only male rhea at the Smithsonian's National Zoo spend Father's Day? He will spend it much like he has spent the past eight weeks: as a proud papa nurturing and caring for his four chicks born April 20. This is the first time in some 30 years that rhea chicks have hatched at the Zoo.
Species still have more viable offspring if they can choose their best mate
When it comes to picking a mate, Crosby, Stills, Nash and Young had an answer: “If you can’t be with the one you love, love the one you’re with.” As it turns out, that may be a cardinal rule in the animal kingdom, too.
Mother's little helpers
An Australian bird has been found to produce smaller, less nourishing eggs when it breeds in the presence of other ‘helper’ birds that provide child-care assistance. This unique adaptation enables the birds to live longer and breed more often than females without helpers. The research, led by a University of Cambridge academic, today made the front cover of
Science.
New Clues to How Sex Evolves
Sex is a boon to evolution; it allows genetic material from parents to recombine, giving rise to a unique new genome. But how did sex itself evolve? Researchers at the Department of Energy's Lawrence Berkeley National Laboratory and the University of California at Berkeley have found clues to one part of this complex question in ongoing studies of the nematode Caenorhabditis elegans.
Certain female fish have special mating preference
Ladies' choice
A biologist at Washington University in St. Louis has shown that for some fish species, females prefer males with larger sexual organs, and actually choose them for mating. That does not exclude males with an average-sized sex organ, called a gonopodium. These fish out-compete the larger-endowed males in a predator-laden environment because they have a faster burst speed than the males with larger genitalia, who lose out because the size of their organ slows them down, making them ripe for capture by larger fish.
When it comes to female red squirrels, it seems any male will do
Researchers have found that female red squirrels showed high levels of multimale mating and would even mate with males that had similar genetic relatedness, basically mating with their relatives.
Positive school environments can help reduce student smoking
A survey of high-school children in Scotland has shown that pupils who experience positive and inclusive social environments in schools are less likely to take up smoking. New research published in the open access journal
BMC Public Health reveals that teachers who succeed in creating a positive environment in school may be responsible for their pupils staying smoke-free.
Zebrafish enable scientists to study the migration of neurons that enable sexual maturity
Scientists are watching a small group of neurons that enable sexual maturity and fertility make a critical journey: from where they form, near the developing nose, to deep inside the brain.
