London - A stripy orange coat seems a bold choice for a predator trying to blend into a forest background.
But it turns out tigers really are camouflaged – even if it doesn’t look like it to us.
Scientists have found that while tigers appear bright orange to humans, their main prey, deer, see them as green.
This is because humans with normal ‘trichromatic’ vision can see red, blue and green lights, but deer lack the right cells in their eyes to detect the colour red.
A study by the University of Bristol used computers to simulate what the world looks like through the eyes of a ‘dichromat’ – an animal which cannot differentiate between red and green.
They did this by generating images of red objects against different backgrounds, including tigers’ natural forest habitat.
Study lead Dr John Fennell said that by simulating what the world looks like to ‘dichromatic’ animals it is possible to ‘identify the optimum colours for concealment and visibility’.
Writing in the Royal Society Journal Interface, he said: ‘The tiger appears orange to a trichromat observer rather than some shade of green, though the latter should be more appropriate camouflage for an ambush hunter in forests.
‘However ... when viewed by a dichromat, the tiger’s colour is very effective.’
Dr Fennell explained while green fur would help tigers to evade their own predators – namely humans – ‘mammalian biochemistry’ makes it impossible for them to produce that colour. The only mammal that does appear green in the wild is the sloth – but only because algae grows in its fur.