The colourful world of birds

Can you imagine a world even more colourful? Recent research has shown that hummingbirds also see ultraviolet light.

»Compared to hummingbirds, humans are colour-blind,« says research leader Mary Caswell Stoddard, a professor of ecology and evolutionary biology.

People perceive color with three different receptors, called cones. With them we see red, blue and green and their combinations. Birds, on the other hand, have four types of cones and, in addition to the basic three colours, also see ultraviolet light.

»That doesn’t mean birds only see one colour more. They see, for example, a mixture of ultraviolet and red or ultraviolet and blue,« Stoddard continues.

A lamp was placed above each feeder, shining in different colours and colour combinations. They always got sweetened water for one colour and plain for the other.

The feeders were constantly moved and it was made sure that the hummingbirds could not smell the sweet water. They thus proved that they [the birds] chose only on the basis of the difference in the colour of the lamp above the feeder.

»We didn’t see a difference between a green lamp and an ultraviolet green lamp, and hummingbirds always went back to the one with the sweetened water,« explains doctoral student Harold Eyster.

In addition to birds, many species of reptiles, fish, and insects see ultraviolet light. Some animals, however, see fewer colours than we do. Dogs and cats have only two types of cones, but they see better than us at night.

Points to Consider

1. Why is good for hummingbirds to see the ultraviolet light?
2. What is your favourite colour?
3. Which birds are also special?

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The original version of this article was published on July 3rd.

English translation courtesy of JL Flanner, Total Slovenia News, an English language website with news from and about Slovenia.