How do swans keep their feathers so white?

Question

My 5 year old daughter and I were at the zoo and she asked me "How do the swans stay so clean when they swim in such dirty water?" They were perfectly white and the water was green.

Answer 1

I think they take a lot of bird baths. Their feathers repel water, otherwise they'd become water logged and wouldn't be able to swim or fly.

Answer 2

Birds spend a lot of time preening-keeping their feathers clean and in good condition. Their ability to fly and to keep warm depends on a well-maintained feather coat.

Birds bathe in birdbaths, along lakeshores and rivers, and even in puddles. After a bath, a bird uses its beak to smooth out its feathers and nibble or pluck away dirt and parasites. With its beak, a bird "zips up" its flight feathers, closing all the gaps that might allow air to flow through and slow down its flight.

Some birds, such as house sparrows, often bathe in dust, which absorbs grime and wipes out parasites.

Most birds finish preening by using the beak to take waxy oil from a preen gland near the tail and spread it on their feathers. The oil keeps feathers flexible. It might also prevent the growth of harmful bacteria and fungi

Answer 3

They have self-cleaning feathers.
They produce oils with which they groom themselves, that keep the water from the feathers. The same oils keep the water from penetrating the feathers, keep the dirt out too. If the bird gets mud on it, the mud will fall off before long.

Answer 4

The water looked dirty but it wasn't, or maybe the feathers are dirt resistant.

Answer 5

oils..naturally generated from their bodies.