Heron at sunset. The color vision of birds stops working considerably earlier in the course of the day than was previously believed, in fact, in the twilight. Birds need between 5 and 20 times as much light as humans to see colors. (Credit: iStockphoto)

ScienceDaily (Nov. 16, 2009) — Research at the Lund University Vision Group can now show that the color vision of birds stops working considerably earlier in the course of the day than was previously believed, in fact, in the twilight. Birds need between 5 and 20 times as much light as humans to see colors.

It has long been known that birds have highly developed color vision that vastly surpasses that of humans. Birds see both more colors and ultraviolet light. However, it was not known what amount of light is necessary for birds to see colors, which has limited the validity of all research on this color vision to bright sunlight only.

"Using behavioral experiments we can now demonstrate that birds lose their color vision in the twilight and show just how much light is needed for birds to be able to interpret color signals," says Olle Lind, a doctoral candidate at the Department of Cell and Organism Biology.

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