Bright birds make better mothers – York study

Colourful birds are better mums than their duller counterparts, York research has revealed.

To us humans, one blue tit may look pretty much like another. But unlike us, birds can see ultra-violet (UV) light.

While the crown of a blue tit looks just blue to us, to another bird it has the added dimension of appearing UV-reflectant.

The three-year study of the birds led by the University of York found that mothers with more UV-reflectant crown feathers did not lay more eggs, but did fledge more offspring than duller females.

The brightly coloured mums also experienced relatively lower levels of stress hormones during arduous periods of chick rearing.

Author Dr Kathryn Arnold said: “Previous studies have shown that male blue tits prefer mates that exhibit highly UV-reflectant crown feathers. Our work shows that this is a wise choice.

“UV plumage can signal maternal quality in blue tits, so a male choosing a brightly coloured female will gain a good mother for his chicks and a less stressed partner.”

Based on research in woodlands on the shores of Loch Lomond, Scotland, the results are published in the journal Behavioral Ecology.

“With up to 14 chicks to care for, blue tit mothers in our study were feeding their broods every couple of minutes,” said Dr Arnold, from York University’s environment department.

“We showed that dowdy coloured females found this level of hard work twice as stressful compared with brighter mothers.

“Also, the mothers with more UV-reflectant crowns were highly successful, fledging up to eight more chicks than females with drabber feathers.”