Ekkies colors is a lifestyle choice

[Beatriz Cazeneuve]

Some female parrots have brightly coloured feathers, looking more like a male, and its their lifestyle that's to blame, an Australian study shows.

The research, headed by ornithologist Dr Robert Heinsohn from Canberra's Australian National University was published in their journal Science.

In the bird world, males usually sport the most beautiful and colourful plumage, then primp, preen and parade for the opposite sex.

In fact, only a handful of species have evolved where the female looks better, and even then it's usually due to a sex role reversal where, for example, the male stays back to care for the offspring while the female goes out competing for mates.

But the parrot Ecletus roratus, originally from New Guinea but found in the rainforests of Queensland's Cape York Peninsula, is unique.

Not only are females' plumage dramatically brighter than males', researchers have now determined that the birds' colour reversal is due to lifestyle factors, not a sex role reversal.

A weird way to mate

The research, carried out in Iron Range National Park over eight years, has unearthed the parrot's rare mating system.

Usually, parrots enjoy social monogamy and share their parental duties. But male and female E. roratus parrots have entirely separate roles during breeding.

This is partly because of the scarcity of suitable nesting spots and intense intrasexual competition: females competing for nest hollows and males for access to breeding females.

It is these lifestyle factors that seem to play a role in the birds' colouring.

Using a model of bird vision, the researchers determined that the red and blue females are more conspicuous than the green males against a visual backdrop of leaves to warn other females away from their nesting spot. In turn, the males are less conspicuous against leaves, which may help protect them against predators while hunting. But they are relatively conspicuous against trunks, which may help them compete with other males for mates.

"This is the only bird in the world that has colours so dramatically different from each other that they were initially thought to be different species," Heinsohn says.

The research team wasn't entirely surprised by the findings, he says.

"We set out to study the parrots because of their 'weirdness'. We knew something strange was going on. But it's taken eight long years of gruelling field work in a hot tropical rainforest to get this far. We didn't know what we'd find, but we knew it would be something interesting."