(CNN)When hummingbirds make decisions regarding food, evading predators or choosing a mate, they're influenced by the diverse colors they can see that are invisible to human eyes, according to a new study.
Hummingbirds can see an array of colors invisible to humans
These are known as nonspectral colors, or hues that come from largely separate parts of the color spectrum. Humans can see one nonspectral color, which is purple.
But it isn't part of the rainbow. Instead, we see purple when the short-wave blue and long-wave red cones in our eyes are stimulated, but not the third green medium-wave cone.
Birds, however, have a fourth cone that can detect ultraviolet light. Their four-color cone vision is referred to as tetrachromatic.
In a new study, researchers set up a field experiment to test how wild broad-tailed hummingbirds reacted to these colors.