Instead of springing straight out of the water into flight, as puddle ducks are able to do, diving ducks must run across the water to build up speed before taking off. Diving ducks, puddle ducks, geese and swans begin migrating north through Pennsylvania in late February. Each year there is a peak in migration, when ponds across the state are crowded with waterfowl. While this period varies from year to year, it often follows heavy nighttime rains in late March or early April. Diving ducks nest in New England, Canada, Midwestern and prairie states, the Pacific Northwest and Alaska.
Several species inhabit both the Eastern and Western hemispheres.
Beginning in winter and before heading north, and into spring, males in their brightly-colored breeding plumage vie for females. Courtship may include ritualized drinking and preening movements, posturing and calling. Copulation takes place in the water. Nesting habits and habitats vary from species to species. Generally, female diving ducks lay 5-15 eggs in vegetation, tree cavities, or rock crevices over or near the water.