I AM PEDRO'S UROPYGIAL GLAND
by Sally Blanchard
Pedro likes to preen his feathers thoroughly at least once a day to keep them in tiptop shape. Pedro is a big healthy Green-winged macaw. During his preening, he often reached down to his lower back and rubs his beak on me. I am his uropygial (that’s pronounced Euro-pij-eal) gland - but you can call me the preen gland for short. The first time that someone told me my real name, I thought they were trying to insult me! I am a very mysterious gland. No one really knows for sure how important I am to Pedro’s welfare. As with the human appendix, his body function is not dependent on me. I am very well developed in Green-winged macaws. We are also well-developed in budgerigars but less developed in cockatiels, finches, canaries, cockatoos, lovebirds, African greys, Eclectus and even my close relative, the Blue and Gold Macaw. Paco, my Amazon parrot friend, doesn’t even have a Uropygial gland. He doesn’t even know what he is missing! We are totally absent in Amazon parrots. I don’t know why any parrot doesn’t need us? Sometimes the uropygial gland becomes impacted or infected. We can even be removed from a bird’s body and I’ve been told that doesn’t seem to even change that bird’s quality of life. But that doesn’t mean that I don’t have some reason to exist. So let’s look at what I do....
I am a bi-lobed gland located on top of and at the base of the tail. Birds, unlike humans, have no sweat glands and only a few sparsely distributed skin glands. I am the main skin gland on Pedro. My function as an Uropygial gland is to allow Pedro access to a holocrine sebaceous secretion, called sebum. Pedro uses his beak to smear this substance all over his feathers when he is preening. This secretion forms a film of fat over the feathers which helps keep them waterproof and helps prevent Pedro’s feather sheaths from drying out and becoming brittle. Sebum also inhibits the growth of microorganisms in birds so that skin infections are fairly rare. It is also believed by some ornithologists that the secretion may also be a form of communication by changing the color or appearance of the feathers during breeding season. So how can other birds get along with poorly developed uropygial glands or even none at all? Why are we so developed in Green-winged macaws and Budgies, who are not even related to each other? How do Amazons get along without us? No one knows that much about the uropygial gland and how important we really are to different birds. This will remain a mystery until more research is done. There is still so much that people don’t know about birds and hopefully as the future unfolds, they will understand more about what makes Pedro’s body work.