This is a plover chick (Luke Eberhart-Philips)
When sex ratio gets skewed towards one gender, parents are more likely to split up, leaving the father to care for the offspring, says a study of bird populations.
The findings of researchers from the Milner Centre for Evolution at the University of Bath are based on a study of six different populations of plovers across Africa, Asia and Latin America.
In three populations of plover, they found a balance in the sex ratio of males to females and so are their shared parenting of their offspring. But in populations where there were more males than females, the parenting too got shifted to the males.
Professor TamÃ¡s SzÃ©kely, Professor of Biodiversity at the University of Bath said: "When there are more males in the population, the females have more opportunities to find partners and so they are more likely to leave the family and mate with multiple partners in the breeding season, leaving their male partner to look after the chicks.
For males, it becomes difficult to get another partner and so they are forced to stay single and take up the primary responsibility of parenting, he noted. Adult sex ratio bias can alter social behaviour with divorce, infidelity, and parental antagonism in sex-biased populations.
"In human societies, adult sex variation is shown to be linked to economic decisions, community violence, and disease prevalence. So we wanted to look at what factors were related to imbalances in adult sex ratio of plover populations," he said.
The study has been published in Nature Communications.