As birds are tetrachromats, they see four colors: UV, blue, green, and red, whereas we are trichromats and can only see three colors: blue, green, red. Bear in mind, that the magenta UV “color” shown here has been chosen to make it visible for us humans, it is a “false color”, as per definition UV light has no color.
The blue receptor can theoretically see UV light but in humans that is filtered by the lens, while in other animals it's not. Doesn't change the fact that most mammals have only two different receptors for color.
It’s typically applied to predators who learn a set of features of their prey such as color, markings, behavior, scent, sound, or some combination of some of those factors. Forming this mental search image speeds up the recognition of the prey and makes the predator more efficient.
Back in 2007, scientists, with the help of a spectrophotometer, analyzed the colors of 166 North American songbird species which did not have an apparent physical difference between the sexes. From a human’s perspective, in 92 percent of species, both males and females look identical.
Bear in mind, that the magenta UV “color” shown here has been chosen to make it visible for us humans, it is a “false color”, as per definition UV light has no color. Image credits: unknown. Image credits: Cynthia Tedore. Joe Smith, an ornithologist, explains that birds have the amazing ability to see a whole spectrum of colors ...