Why Do Birds Preen Themselves?
Birds preen themselves to clean and waterproof their feathers, to maintain their general health and to keep them lying smooth and neat. Most birds will preen several times a day. This preening or grooming starts as the nestling’s feathers are breaking out of their sheaths. The young bird spends a great deal of time combing the feathers with its bill and freeing them from bits of sheath and other blemishes.
In adult life the bird continues this behavior and also uses the preen glands or oil glands which are located on the back, just in front of the tail. The birds nibble at the glands and rub their heads against them, spreading the secretion on their feathers. This oil waterproofs the plumage, keeps it supple and maintains its insulating qualities. The oil may also be useful as a source of Vitamin D if swallowed accidentally by the bird.
Birds use their bills and feet to preen each feather on their body, methodically nibbling or stroking every feather from its base to its tip to get it aligned just so. Birders are familiar with different contortions birds will use in order to reach every feather, and it is not unusual to see a bird in an unusual and odd position while preening. There are other behaviors, however, that are also a part of preening.
Many kinds of birds have preen glands. They often combine preening with dust or water bathing. Ducks may be seen dipping their heads under water, flicking their wings and wriggling their bodies while preening. This seems to give them great pleasure and fun.
Some types of birds, including owls, pigeons, parrots and hawks, lack a uropygial gland. Instead, these birds have specialized feathers that disintegrate into powder down, which serves the same purpose as preen oil. Birds that produce powder down are less likely to bathe or immerse themselves in water and do not require the stronger waterproofing that preen oil provides.
Preening serves several essential purposes for birds, including:
Aligning feathers for optimum waterproofing and insulation to protect against adverse conditions, such as soaking or extreme temperatures.
Aligning feathers into the most aerodynamic shape for easier, more efficient flight. This helps birds use less energy in flight and make more acrobatic moves.
Removing feather parasites and body lice that can destroy feathers or carry disease. This keeps birds healthier and protects the entire flock or nest from an outbreak.
Removing tough sheaths from newly molted feathers. Removing these sheaths helps gets feathers into the proper position more quickly so they can be useful right away.
Creating a healthier appearance to attract a mate. A healthier, more attractive bird will attract a stronger mate and have a better chance of raising many strong, healthy chicks.
Bonding between mates as a courtship ritual that involves mutual preening, called allopreening. This is a form of communication between mates and helps keep their connection strong.
With so many reasons to preen, it is no surprise that many birds engage in this behavior for several hours a day.