When You’re a Bird, the World Always Looks Psychedelic
Reposted from Audubon.org, an ornithologist explains how birds can see a whole range of colours that people can’t.

Birds have one more photoreceptor than humans: ultraviolet. Here, from left to right, are eggs as we see them and simulations of what they look like with only UV vision and what they might look like to a bird. Photo: Adapted from Bird Sense: What It’s Like to be a Bird (Walker Publishing, 2012). Photo by Joel Sartore.