Imagine if the human brain could interpret light in the ultraviolet spectrum. The world around us would look similar to the picture above.
Even more fascinating, is that this is how the rods and cones of a birds eye interpret light. In fact, birds can largely be separated into two categories: those that see in UV light, and those that see in what we call “visible light” (usually nocturnal birds). Over the past 30 years, we’ve learned not only that this ability exists, but that it defines their behavior. 2
Studies have shown that many birds plumage is highly reflective to UV light, which explains the fantastic array of colors many species display. This aids in mate selection and helps birds find each other in dense brush. Studies have also shown that this reflectivity allows birds to signal to each other.
Birds also use this ability to find food, as many moths, butterflies and insects have UV-reflective exteriors. This allows a foraging bird to quickly identify prey. Many raptor-type birds, like the common kestrel, hunt small mammals wandering through the plains. Some of these mammals behave much like dogs, leaving trails of urine to mark their territory. Finish researchers from the University of Turku discovered that some of this urine is reflective to UV light, allowing flying predators to see their tracks from the sky.
UV light also aides some female birds in choosing which of her chicks to feed first. In a nest full of chicks, it can be difficult for the female to accurately delegate food she has collected. European roller chicks, for instance, have a patch of bare skin on the tops of their heads, highly reflective to UV light. In newly-hatched chicks of this species, the patch is larger, signaling to the mother that this chick needs to be fed first, and higher quantities.
We can’t really comprehend what it would be like to see the world in UV light, but we can get close. Even with all our knowledge and technology, in many ways, we’re still outclassed by nature.