What does a pigeon look like?
July 15, 2011 11:39 AM   Subscribe

I got curious about this after reading a blog article on pigeons and face recognition. What colors does a pigeon see in other pigeons? I see pigeons with white, black, and grey bands and patches, sometimes with iridescence in the neck. The wikipedia entry for bird vision says they have pentachromatic vision.

In the experiment, the two humans changed lab coats. The article does not show a picture of the coats, but I've been wondering if they were solid colors or patterned. If the humans wore lab coats that resembled patterns in the plumage of a pigeon, maybe they'd be harder to recognize when they swapped the coats. Do pigeons pay attention to uniform expanses of color?

What advantages do they get from pentachromatic vision? How does a pentachromatic eye perceive colors in a scene? And, this also had me wondering, why don't pigeons have more variations in the color of their feathers? Or maybe they do, but not in my frequency range?
posted by bleary to Pets & Animals (6 answers total) 5 users marked this as a favorite
I also wondered about swapping lab coats. Given that pigeons are low to the ground, could they have recognized the "hostile" human by the shoes or pants color? I don't have an answer to your question, but you reminded me of mine.
posted by klausman at 12:43 PM on July 15, 2011

And, this also had me wondering, why don't pigeons have more variations in the color of their feathers? Or maybe they do, but not in my frequency range?

Pigeons are the dogs of the bird world. In the wild, they tend to be fairly uniform, but domestic breeds are tremendously varied.
posted by Sys Rq at 1:03 PM on July 15, 2011

from a 2004 journal article abstract: (Click through and you can see a thumbnail of the spectrum for free)

"Neck feathers that appear purple to the human eye exhibit four reflectance peaks—two in the UV and one in the blue and red regions—and thus exhibit a UV-purple hue. Neck feathers that appear green to the human eye are characterized by five spectral peaks: two in the UV (UVA and UVB), a predominant green peak, and secondary violet and red peaks, conferring a UV-purple-green color."

One advantage of pentachromatic vision is just extending the frequency range that the bird is sensitive to. It would be hard to describe what that looks like, since it's hard to imagine what it's like to see UV. Another advantage is resolution; having effectively a fourth detector aside from our (roughly speaking RGB) three could mean being able to tell the difference between colors that look very much the same to us. Like the friend who calls your three green shirts forest, jungle, and hunter, only more so. Like the difference between a 16-bit and a 256-bit color rendering, only if your eyes were so good that 256-bit looked crappy.

A related piece of trivia - bees, as well as some birds, are polarization sensitive. (n.b. useful for navigation when the sun is clouded) We can use polarizing filters to detect polarization as being bright or dim after that filter is applied, but I honestly can't imagine what it would be like to be able to tell what polarization something is by looking at it. A human eye could plot a point in 4-D, with an axis for brightness (rods), redness, blueness, greenness... and birds would add a 5th dimension of UV-ness, pigeons a 6th color dimension... but now imagine a dimension of polarization - it doesn't look brighter, or different colored, it just looks... polarized?? I'm fascinated and confused by the very idea of it.
posted by aimedwander at 1:09 PM on July 15, 2011 [3 favorites]

If you've ever used UV filtered glasses, you might have seen some odd color effects. The edges of torn newspaper have a pink shading, for example. I'll bet that feathers have some kind of refractive UV effect similar to the torn paper fibers.
posted by StickyCarpet at 1:50 PM on July 15, 2011

If they're pentachromats, they see extra primary colors that we don't see. What colors we see depend on how our eyes and brains work.

Look at it the other way-- consider red-green color blindness, where one of the three types of human receptors doesn't work. Those folks lack some of the colors the rest of us see.

It's not just a frequency range thing, though that's part of it (pigeons can see UV light). They'd see more colors within the spectrum that we see.
posted by zompist at 9:16 PM on July 15, 2011

I wonder if seeing polarization would allow an organism to see turbulence in the air.

It's hard to overstate how important that might be for flying organisms.

The abstract of this article seems to hold out some slight hope of an illuminating discussion of the effect of turbulence on polarized light, but it would cost $45 to explore that possibility.
posted by jamjam at 3:24 PM on July 16, 2011

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