They stay during winter because ducks' bodies have a nice layer of cold-resistant fat and multiple layers of feathers for keeping the water out and the heat in.
They can also tuck their feet up against their bodies and, unlike chickens, don't have cold-vulnerable combs on the tops of their heads.
Ducks can easily handle up to -20°C and like to waddle around in the winter ponds, dive in the water or just chill on the ice or snow.
Here's some pictures of just that taken in Scandinavia in mars this year.
@thewindupbirdchronicles It's from, 'the Catcher in the Rye'. Holden asked a couple of cab drivers the first one just blew him off, but the second one at least thought about it and came up with the fish analogy.
@Lostpoet Hmm, interesting and thank you for that tidbit of knowledge. In this world, while many a cab driver may be gruff, they are likely the last to blow you off in story as they have heard them all.
