Biology Reference
In-Depth Information
FEATHER CARE
Feathers are a wonderful adaptation for flying creatures. If a bat flying through trees ac-
cidentally tore a wing on a branch, the injury could permanently ground it. If a bird were
in the same kind of collision, the branch might damage a feather or two but more likely
would simply part two feathers, which the bird could realign simply by preening.
Basic Grooming
As wonderful as feathers are, they must be properly groomed to hold up under the rigors
of a bird's daily life. Birds nibble them to realign hooks and barbules to maintain the in-
tegrity of the vanes, and in the course of this preening they pick off lice and mites, too.
To keep feathers supple and protected from sun, wind, rain, and saltwater damage, most
birdshaveaglandatthebaseofthetailcalledauropygialglandor“preengland.”During
preening, birds nibble at this small, pimplelike structure to squeeze out drops of oil that
they work into their feathers to keep them supple and in good condition, as hand lotion
candoforourskin.Theoilmayalsofosterhelpfulspeciesoffungusthatprotectfeathers
from parasites while helping control harmful fungus growth.
People once believed that the oil secreted by this preen gland directly waterproofed
feathers, but when researchers removed the preen gland from ducks, they found that the
feathers continued to be waterproof until, over time, they grew brittle and started break-
ing. Apparently the oil indirectly contributes to waterproofing not by repelling water it-
self but by helping the feathers to maintain their structure.
Parasite Prevention
Mites and some other ectoparasites eat feathers, damaging hooks and barbules. Preening
helps get rid of these pests but often isn't enough, so many birds engage in additional
activities. In one, called “anting,” birds apparently take advantage of the formic acid or
another strong chemical in ants to repel mites. There are two techniques for anting. In
passiveanting,thebirdsitsstill,almostasifinatrance,onananthillorotherspotwhere
ants are swarming, allowing them to crawl through its feathers. In active anting, the bird
picks up an ant or other thing with strong chemicals, such as a mothball or cigarette butt,
and smears it on its feathers. Sometimes after this active anting, the bird eats the remain-
ing insect.
