I have so many questions about this…

Take a look at this Avocet flying by. Have you seen the state of its toes? Covered in brown mud?

That, however, isn’t what’s remarkable about this Avocet. Have you seen how clean the rest of the bird is?

Exactly how does a bird with pure white feathers keep itself so clean? Remarkable, isn’t it? It’s clearly something which has evolved in these birds and not in dogs, given the state of the white dog I saw completely covered in brown mud on its lower half.

Birds have a uropygial gland at the base of the tail which exudes a waterproof substance. It consists of a waxy oil, called preen oil. In it are a complex mixture of diester waxes, fats, and fatty acids. It’s what all that frantic preening is about, with Avocets rubbing their preen gland to release the oil and then spreading it all over their feathers. They even manage to get it on the tops and backs of their heads., which is a talent.

I wish I had some on my trousers. And if we ever manage to synthesise it and bottle it commercially, I know a few dog owners who would pay a pretty penny for it.