Both adults are involved in incubating the eggs for 29 to 31 days. The eggs hatch in late May or early June. The eggs in each nest hatch at different times, and the second egg or chick often is pushed out of the nest or starves to death. The current nesting area in Wood Buffalo National Park lies near the headwaters of the Little Buffalo, Klewi, Sass and Nyarling rivers. The area is interspersed with potholes and is poorly drained.
Wetlands vary considerably in size, shape and depth, and most have soft marl bottoms.
Approximately 22,500 acres of salt flats and marshes on Aransas NWR and adjacent areas comprise the principal wintering grounds. Interior portions of the refuge that are periodically used by foraging whooping cranes are gently rolling and sandy grasslands with swales and ponds. Although a variety of habitats are used during migration, a wetland is always used for night roosting and frequently for foraging. While migrating, whooping cranes roost standing in the shallow water of marshes, flooded crop fields, artificial ponds, reservoirs and rivers. Wetlands surrounded by tall trees or other visual obstructions, or marked with dense vegetation are not used.