The process in which birds spread oil on their feathers using their beaks is called ___.

a.

preening

c.

brooding

b.

molting

d.

none of the above

While preening, birds spread this oil to each feather so they are evenly coated and protected. Some types of birds, including owls, pigeons, parrots and hawks, lack a uropygial gland. Instead, these birds have specialized feathersthat disintegrate into powder down, which serves the same purpose as preen oil