Birds also need sunlight to synthesize vitamin D, but their skin is blocked by their feathers. So the chemical precursors to vitamin D are in their “preening oil”, a substance they secrete from a gland and rub on their feathers with their beak, an activity called preening. The sunlight hits it and forms the vitamin D, and they end up swallowing enough of it the next time they preen. The preening oil also contributes to the feather’s waterproofing and keeps them flexible.
Random interesting thing:
Birds also need sunlight to synthesize vitamin D, but their skin is blocked by their feathers. So the chemical precursors to vitamin D are in their “preening oil”, a substance they secrete from a gland and rub on their feathers with their beak, an activity called preening. The sunlight hits it and forms the vitamin D, and they end up swallowing enough of it the next time they preen. The preening oil also contributes to the feather’s waterproofing and keeps them flexible.
That’s pretty cool. Random interesting facts are the best.