London, May 21 : A new study has determined that chameleons have the ability to fine-tune their color changes to the visual systems of specific predators.
According to a report in New Scientist, Devi Stuart-Fox at the University of Melbourne, Australia, and colleagues carried out the study.
The team studied the Smith's dwarf chameleon, which lives in South Africa, and is a critically endangered chameleon that can alter its colour palette in milliseconds, either for camouflage or for social signalling.
The team captured eight males and eight females of the species.
They placed them on a branch and presented them with realistic models of two of their biggest predators: the fiscal shrike, which is a bird that impales chameleons on thorns before eating them, and a venomous tree snake called the booms Lang.
Using a spectrometer, the team took readings of the colour shades and brightness of the background and the chameleon. Then, after the chameleon had spotted the model predator and changed colour, they took another set of readings.
The team found that chameleons colour-matched their backgrounds much more closely when presented with a bird than a snake.
However, when the team modelled the visual systems of both predators, they found that the chameleon still appeared better camouflaged to the snake than the bird, thanks to the snake's relatively poor colour vision.
In the presence of a snake, it seems, the chameleons just don't have to try as hard.
The researchers noticed that the chameleons were also consistently paler, compared with their background, when presented with the tree snake.
"This is probably because while birds usually approach from above, putting the chameleon against a dark background, snakes usually approach from below, putting it against a background of a light, bright sky," said Stuart-Fox.