Invasion of the Quackers

Lately a lot of ducks have been hanging out on the small lake behind our house. My pal Mullins has accused me of me of being obsessed with the ducks in a way similar to Tony Soprano. I don't think things have gone that far, but I have been wondering how a particular baby ducky is going to survive the oncoming Winter. How old does a duck have to be before it can fly South?