Why the White?

Explanation: Take a good look at this week's star, in the above photo. This is a beautiful bird of the coastal swamp woodlands of north tropical Australia, a Forest Kingfisher. It has a deep, strikingly violet head, wings, back, and tail. But ... underneath? White. And the forehead? White!

Why the white?

More specifically, what could be the adaptive advantage to having evolved such a color pattern?

Well, as far as the white below goes, on the chest and belly, we rather addressed that in a previous EPOW episode, having spotted a different bird species in the same region. Check that out for the answer.

But ... why the white forehead? One initial idea that came to me was that the white patch lies between the eyes, so maybe it had to so something with vision ... such as with helping to align eyesight to better catch prey, or somehow enabling depth perception.

Nope.

Then, a less obvious answer came to me after I photographed this same bird as it tilted its head down:

That white patch turned out to be two patches ... that, for all purposes, seem to look like big eyes!

So my hypothesis -- not studied, as far as I know -- is that such white patches serve as an anti-predator display, making the bird look like it is always watching, always on the lookout, should a predator, such a hawk, be making its move, to dissuade the predator from attacking, especially from above, as they so often do.

I've not seen this hypothesis advanced before, and there may very well be other alternative explanations.

And also, of course, an adaptation could very well serve more than one purpose, as well.

So, for now, my working hypothesis at least tentative explains why the white?

EPOW - Ecology Picture of the Week