BISMARCK, N.D. (AP) — State wildlife officials say sightings of whooping cranes are expected to increase in North Dakota over the next several weeks.

The endangered birds are in the midst of their spring migration. The whooping cranes that make their way through North Dakota each spring are part of a population of about 500 birds migrating from their wintering grounds at Aransas National Wildlife Refuge in Texas to their nesting grounds at Wood Buffalo National Park in Canada. That’s a distance of about 2,500 miles (4,023 kilometers).

Whooping cranes stand about 5 feet (1.5 meters) tall and have a wingspan of about 7 feet (2 meters) from tip to tip. The birds are bright white with black wingtips that are visible only when the wings are outspread. Whooping cranes usually migrate singly, or in groups of two to three birds, and may be associated with sandhill cranes.

The North Dakota Game and Fish Department says anyone seeing whooping cranes is asked to report sightings so the birds can be tracked.