I thought they were going to fly south

My daughter goes to pre-school at the YMCA which is next to a river. There are many geese and ducks that like to hang out at the river next to the YMCA. My daughter likes to chase them in the spring when it's nice outside.

I was under the impression however, that geese and ducks fly south for the winter because it gets very very very cold in MI. So cold that the ponds freeze.

The geese are not flying south though. They're still there hanging out in the park and by the river and in the parking lot.

Are they going to fly south? If not what will they do when all the small bodies of water freeze and what will they eat?