17.009 Birds see colours, which we cannot perceive at all

Viola Ulrich
Hummingbirds see colours, which we cannot even imagine
WELT, 21.08.2020
Birds see colours, which we cannot perceive at all

Colourful tininess

Hummingbirds see colours, which we cannot even imagine

By Viola Ulrich

We men obviously miss quite a bit. So for hummingbirds the world looks a little more colourful than for us. For the little birds see colours, which we cannot perceive at all.

We men possess three colour receptors in the eye, with which we see red, green and blue light. In addition we can still perceive purple - a non-spectral colour, which not just stimulates one optical cone (Sehzapfen) from a combination of wave lengths, but several. Exactly: the red and the blue.

So most insects for example possess nine colour sensors, some crustaceans even twelve and butterflies up to 15 cone types.

Birds are so-called tetra chromates. They have four little optical cones and can, in addition to the normal colours, also still see ultraviolet light with it.

Sehzapfen

"A fourth cone not only extends the area of the colours in the ultraviolet area visible for birds, but lets them possibly also perceive combinations like ultraviolet + green and ultraviolet + red - but this was up to now difficult to find out", explained the biologist Mary Caswell Stoddard in a press announcement.

Stoddard and her research colleagues were certainly not discouraged by this. For their study, which appeared now in the specialist paper "PNAS", they have tested all through three years wild broad tailed hummingbirds in free nature on a meadow in the Rocky Mountains. The scientists have for this purpose arranged feeding places with LED lamps. Their spectrum comprised, next to the colours visible to us, also the non-spectral colours ultraviolet + green, ultraviolet + red, ultraviolet + yellow, ultraviolet + purple and purple. The scientists taught the about nine-centimetre birds, that there was sugar water at the ultraviolet lamps only, with the others they just got simple water.

The hummingbirds learned really fast, with which colours the delicacies waited for them, and headed for the feeding places, which were equipped with ultraviolet LEDs, even so the researchers had rearranged them.

"It was fascinating to see", said the co-study author Harold Eyster of the Canadian University of British Columbia. "The ultraviolet + green and the green light looked to us identical, but the hummingbirds chose quite correctly again and again the ultraviolet + green light linked to the sugar water."

The experiments showed, that hummingbirds can perceive a large number of non-spectral colours like ultraviolet + green, ultraviolet + red, ultraviolet + yellow and purple.

Moreover, the birds could distinguish ultraviolet + green from a pure ultraviolet and genuine green, as well as two different ultraviolet + red tones.

The colour perception probably helps the hummingbirds, to find rewarding sources of nectar faster, since many flowers shine in the ultraviolet area. Moreover, non-spectral colours are also found in the plumage of the birds, so that the animals communicate with each other via visual signals.

Previous webpage: 17.008 Next webpage: 17.010

Start: To the start of this webpage.

[Home]>[Miscellaneous]>[7. The Solar System]>[17. Light]>[17.009 Birds see colours, which we cannot perceive at all]

[Home] [How to Measure Your Beliefs] [The Man-Made Church] [Miscellaneous]

The address of this webpage is:
http://www.fpreuss.com/en3/en02/en0217/en0217009.htm