The prairie potholes offer a good example.
Potholes come in all shapes and sizes, with an equally varied array of lifespans.
But the ducks make use of them all. Where to see Wetlands Click here for some of John Grassy's picks. When teal, gadwall, mallard, wigeon, and other ducks complete their northward migration, the larger potholes are still cold and dormant. The smallest potholes, often called pair ponds, are not. But these shallow pools warm rapidly.