Those of us who love to garden also love to stroll through those gardens to enjoy the colors and scents and feel the ambience. Many of us also enjoy watching the birds that come. We even en- courage their presence with bird feeders and bird baths.
Did you ever stop to think that the way we see in our gardens is not what the birds see? In the early 1970’s researchers accidentally discovered that birds can see in the ultraviolet spectrum. In fact, they are more sensitive to UV than to what we call visible light. Our eyes detect color because our retinas have three kinds of cone
cells, which are the receptors used for color vision. Birds, at least those who are active during the day, have four, in- cluding one that is specifically sensitive to UV wavelengths. Each of their cone cells also contains a tiny drop of colored oil that functions much like a filter on a camera lens so they are better than we are at detecting differences between similar colors. These abilities come in handy in finding food.
Many insects, including moths and butterflies, have body coatings that strongly reflect UV light. Berries and fruits de- velop highly reflective waxy coatings as they ripen. Many seeds are also reflective. Raptors use UV to track prey. Voles, mice and other rodents use urine to mark their territory. Urine is brilliantly visible in UV light so raptors can determine exactly where a prey is located, even when the prey may not be visible to us. The ability to see UV light influences how they see each other as well as helping them detect eggs in their nests that may not be their own.
Understanding how birds see color has given rise to enhancing equipment and backyard birding tools. Adding UV re- flective properties to window decals can reduce bird window collisions. Designing pet collars and tags that reflect UV light may make these predators more easily visible to birds. Treating field bags or clothing to not reflect UV light, cre- ates a more effective camouflage for birding gear. Designing bird feeders with UV patterns can entice birds to visit new bird feeders more easily.
So while enjoying your garden, know that what you are seeing is not what our feathered friends are seeing!