Biology Reference
In-Depth Information
Q Do birds see colors?
A
Yes, they do, and they can even see some wavelengths in the light spectrum that are
invisible to humans. Birds use their excellent color vision to find food, such as ripe fruits
and flowers. Their colorful plumage is also important in courtship. Many studies have
shown that when given a choice, female birds often prefer males with the most colorful
feathers.
Birds can detect polarized light that humans can't see. Experiments show that pigeons
and migratory songbirds use polarized light as a cue to help them navigate in the right
direction.
Birdscanalsoseeultravioletlight,whichisinvisibletous.Feathersreflectintheultra-
violet spectrum, and birds can see and use this information to help them discern sex and
age differences in one another and even recognize individuals. In experiments in which
female flycatchers could choose between a male with normal feathers and one treated
with sunscreen to block the UV-reflection of his feathers, females showed a strong pref-
erence for normal, ultraviolet-reflecting feathers.
Many birds, including seabirds such as terns, gulls, and albatrosses, have red or yellow
oildroplets,containinghighconcentrationsofcarotenoids(thesamepigmentsthatmake
carrots orange) within the cone cells in their eyes. Light travels through the oil droplets
before it reaches the visual pigments. The oil droplets filter out some wavelengths of
light, narrowing the color range that each cone perceives, which means the cones per-
ceive colors more accurately than we can; birds with these oil droplets apparently also
see better in hazy or watery conditions.
The ability to see ultraviolet light also comes in handy for finding food. Kestrels can
actually see where their prey — small rodents called voles — have been walking. Fresh
trails reflect UV light from urine that the voles have left behind, so kestrels can detect
