“We, the people, in comparison with birds about as color-blind against people with normal vision,” says evolutionary biologist Mary Caswell from Princeton University (USA). In our eyes there are only three kinds of photosensitive cones to respond to blue, red and green. And those same hummingbirds have another type of cone, for communication with the ultraviolet color. Therefore they are called tetrachromats.

Most interesting is that birds don’t just see in a wider wavelength range, they are able to distinguish between the combined colors. For example, ultraviolet or UV and red and green. We, the people, it is difficult to imagine how this principle might look like. Hummingbirds, according to preliminary data, can discern at least five types of such combinations.

Team Caswell conducted thousands of experiments that proved the ability of hummingbirds to see beyond the human color spectrum. And not just to see, and very accurately distinguish between shades, solving little puzzles that you have prepared for them the scientists.

In another study, which affected the plumage 1,000 different species of birds and 2400 species of plants, it turned out – the surface structure over a third of which is such that it reflects light in the invisible spectrum. That is, at least a third of wildlife has the coloring that people will never see, and therefore will not be able to apply in their work. This is about how to assess historical events only in black-and-white pictures, which cuts off many important details associated with different colors.
Source — PNAS