No modesty please!

But male blue tits,apparently,judge females by their looks.

For the study,published online in the journal Frontiers in Zoology,scientists captured females while they were taking care of chicks and assigned them to a control group,smearing the crests of the first group with UV-blocking chemicals to make the feathers look dull. Then they restored the birds to their nests.

The male birds made fewer feeding excursions to the females with the UV-blocking chemicals on their feathers. The reason is that males judged females with poor colouration less likely to produce healthy offspringwhat the researchers call the differential allocation hypothesis.

This is one of the first studies to focus on females to observe changes in males behaviour, said Matteo Griggio,a researcher at the University of Veterinary Medicine in Vienna.