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Peacock tails are brightly coloured and highly conspicuous – but maybe not to their predators. The animals that hunt peacocks have poor colour vision and, to their eyes, the birds’ tails may actually help them blend into the background.

However, it is not clear whether this colour-based camouflage helps the peacocks much, because they make themselves noticeable in so many other ways.

Peacocks are male Indian peafowl (Pavo cristatus). When they court the female peahens, they display an enormous tail decorated with iridescent eyespots. All else being equal, peahens prefer males with more elaborate and beautiful tails.

We had thought that the tail’s bright colours also attract the attention of predators. In the birds’ native south Asia, the threats include tigers, leopards and stray dogs.

Invisible peacocks

But it is not obvious that these animals would take notice of peacock tails, because their colour vision is not as good as ours, argue Suzanne Amador Kane of Haverford College in Pennsylvania and her colleagues.

Human eyes have three kinds of colour-sensitive receptors, which mean most of us can tell the difference between colours like red and green. But cats and dogs only have two colour-sensitive receptors, so some hues look the same to them.

Kane’s team used spectroscopes to measure the light reflected be peacock tails, to determine their exact colours. Then they calculated how the tails would appear to other peafowl, and to their predators.

They found that the famous eyespots are conspicuous to peafowl but blend in for the predators. What’s more, when shown against a background of foliage the peacock tails further blended in.

The team argues that peacock tails have evolved to form a kind of secret communication channel that other peafowl can see, but which their predators are not aware of.

Other researchers are a bit more sceptical. “They’re saying that peacock colour is helpful in making them basically invisible to predators,” says Marion Petrie of Newcastle University in the UK. “I really don’t buy that.”

For starters, the camouflage would only work from the front. Seen from behind, peacocks have a bright white tail, which wouldn’t hide much says Petrie.

We should also bear in mind how peacocks behave during the mating season, says Petrie. “At the end of the day, it’s a great big bird, it’s not seeking to camouflage itself,” she says. “It shouts, it rustles its feathers, there’s a lot of movement when it’s courting another bird. It’s not skulking around in the bushes trying to hide away from predators.”