Can hummingbirds see ultraviolet light?

Yes. Hummingbirds have a dedicated ultraviolet cone with peak sensitivity near 371 nm, well outside the human visible range. It functions as a fourth, independent color channel rather than a minor add-on.

How many colors can a hummingbird see?

There is no single number, but hummingbird color space is a four-dimensional volume rather than the three-dimensional space humans use. Practically, that means they perceive at least five nonspectral colors — UV+red, UV+green, UV+yellow, UV+purple, and purple — where humans perceive only purple.

What is a nonspectral color?

A color that cannot be produced by any single wavelength of light and requires stimulating non-adjacent cone types at once. Purple is the human example. For hummingbirds, combinations of the UV cone with the green or red cones create additional nonspectral hues with no human equivalent.

Do hummingbirds really prefer the color red?

Red is a reliable signal because bees see it poorly, so red flowers advertise mainly to birds. But hummingbirds are not restricted to red — they investigate many colors and, once a feeder is established, rely far more on spatial memory than on color.

Should I use red dye in hummingbird nectar so they can see it?

No. The feeder's own red parts provide the visual signal, and the birds find feeders by memory. Red dye adds no attraction benefit and is not something a hummingbird's body needs to process. Plain 4:1 sugar water is the recommended choice.

Why does a hummingbird's throat change color?

The gorget is structural color, not pigment. Stacked melanin platelets create optical interference, so the color appears and disappears with viewing angle — effectively letting the bird aim a flash of color at a specific target.

Do hummingbirds see UV patterns on flowers?

Many flowers carry ultraviolet nectar guides that are invisible to humans but clearly visible to birds and insects. Native plants that evolved alongside local hummingbirds are most likely to carry the signals those birds are tuned to.

How was hummingbird color vision tested in the wild?

Researchers at the Rocky Mountain Biological Laboratory trained wild broad-tailed hummingbirds using custom LED tubes that could emit ultraviolet along with visible light, pairing rewarding and non-rewarding feeders. Across roughly 6,000 foraging visits the birds discriminated nonspectral colors well above chance (Stoddard et al. 2020).

How Hummingbirds See Color: Inside the Tetrachromatic UV Eye | NectarBloom™