It’s a common myth that the waxy substance from a bird’s uropygial, or “preen”, gland is what makes feathers waterproof. This is not the case. While the waxy secretion is vital for the long-term health and maintenance of each feather, it is the remarkable physical structure of the feather itself that makes feathers waterproof.
Each covert feather on a bird is structured so that, when all of its parts are aligned and “zipped” together *just right*, it creates a mesh much like GORE-TEX™ with gaps too small for water with normal surface tension to penetrate.
When a bird is contaminated with an oily substance, just as it is on a piece of clothing, even GORE-TEX™, only a thorough washing with the right tools under the right conditions can remove all of the oil and leave no residue. And, after years of practice, teams at Bird Rescue are professionals with the skills and training required to clean them. Once a contaminant is removed, then the work is up to the animals themselves: they will need to re-waterproof their feathers by preening, that is realigning the hooks and barbules to re-create that waterproof mesh. Once waterproof, our patients can then return to the wild.
This is where those uropygial gland oils come into play. It takes a long time to grow such a complex coat, and most birds replace their feathers only once a year because of the metabolic costs. So, that waxy substance is like a bird’s own feather conditioner, critical to keeping feathers supple and flexible so they will last and keep those little gaps tiny for a full year!
Also, check out How Oil Affects Birds