London, Sep 23 (IANS): The bright colours that male lizards use for sexual signalling to attract females also increase their exposure to preying birds, new research reveals.

Using models that replicated the colouration of male and female wall lizards found on the Greek islands of Skopelos and Syros, the researchers found that the male lizard models were less well camouflaged against their habitat and more likely to fall prey to bird attacks.

"It has previously been assumed that conspicuous male colours are costly to survival, but this has not been tested before among these specific lizards living on different islands, and in general rarely in a way that takes into account the particular sensitivities of avian vision," said lead study author Kate Marshall from University of Cambridge.

To test whether the males really are more visible to feathered predators, the researchers had to develop clay models that accurately replicated the lizards' colour to a bird's eye.

Using visual modelling, they tested around 300 colour variations to find ones that matched the male and female colours in order to make the 600 clay lizards used in the study.

The researcher placed the male and female lizard models in 10 sites on each of the two islands and checked them every 24 hours over five days to see which had been attacked by birds.

"The models that had been attacked showed signs of beak marks, particularly around the head, and some had been decapitated," Marshall explained.

At the end of the study, the researchers found that the models with male colouration had been attacked more than the models with female colouration.

The study appeared in the journal Ecology and Evolution.