Little penguins preen their feathers to keep them waterproof. All cormorants have preen gland secretions that are used ostensibly to keep the feathers waterproof. They have dense plumage with a large preen gland for waterproofing their feathers. Birds of a flock will preen each other, ruffling their head feathers in invitation. They do not have rectrices (tail feathers) or a preen gland. Mated pairs will often preen each other's feathers. The tail consists of twelve feathers and the preen gland has a tuft. The pecten is also used to preen feathers and to hold slippery food items. They also preen other birds' feathers that are otherwise hard to get at. They love to snuggle and will often preen their favorite people. Many parrots also like to gently beak or attempt to preen their owner's hands. In mammals, the gland secretes an oily substance used to preen the fur. Fighting European starlings will break off their battles to preen. Poultry have a gland called the preen gland that secrets an oily salty tasting substances. They preen themselves frequently, particularly when roosting in the middle of the day.