Have you ever wondered how ducks stay warm even though they spend most of their time in water?
A clue to this question can be found in this well-worn idiom:
Fred told Polly to give up and go home. His advice was like water off a duck’s back, and she persisted.
Did Fred dampen Polly’s determination? No way! Polly’s self-esteem was as impervious to Fred’s discouragement just as a duck’s back is impervious to water. Duck feathers are waterproof, you see. A duck can spend all day splashing around in ponds and never get wet.
We turned to this book to understand how this waterproofing works:
Ducks Don’t Get Wet by Augusta Golden helped us understand how ducks waterproof their feathers. It turns out that ducks have special oil glands near their tails. They stroke the gland with their bills to collect the oil, and smear it all over their feathers. Since oil and water don’t mix, oily feathers keep the water out, and their skin stays dry. This behavior is called preening. A duck must spend hours preening everyday in order to stay warm, dry, and healthy.
We tried a simple experiment to demonstrate what happens when water meets oil. Each kid got a small bowl and three tablespoons of baby oil. Using pipettes, they squeezed drops of brightly colored water into the oil and observed how the two substances interact. The results were as convincing as they were colorful.