The sandhill crane (Grus canadensis) is one of the two crane species native to North America. It is a large, wading bird with long black legs, long neck, and black, chisel-shaped beak. Adults are usually four feet tall, with a wingspan of about six feet.
There are six recognized subspecies of the sandhill crane, with three being migratory and the remaining being non-migratory. The lesser sandhill crane subspecies is migratory and can be found during the winters in the southcentral United States and Mexico. There are about 550,000 sandhill cranes in the mid-continental population, which accounts for at least 80 percent of all sandhill cranes. They migrate through a zone called the Central Flyway, each spring to breed in the north-central U.S., Canada, Alaska and Siberia.
Sandhill cranes mature at three to five years of age and mate for life. Cranes prefer to nest in remote, inaccessible wetland areas. They construct simple nests by scraping vegetation into a mound. In late April or early May, they typically lay two oval-shaped eggs. The eggs are greenish or brownish with dark spots.
Both males and females take turns incubating the eggs for one month. The chicks are tawny-colored and develop rapidly. Since incubation begins as soon as the first egg is laid, the eggs hatch a day or two apart. The older chick is more likely to survive, and within 10 weeks the young, called colts, are ready to take their first flight.
Adult plumage is attained by about two years of age. Mature birds are gray with white cheeks and a bare reddish forehead. Some of the mature birds’ plumage takes on a rusty color, which is caused by the iron stain picked up in the peat bogs and muskegs of their breeding ground
Cranes are omnivorous ground feeders and will eat frogs, rodents, insects, bulbs, seeds, and berries, as well as aquatic invertebrates and animals. They also have adapted to agriculture by feeding on waste grain and small animals in farm fields.
Sandhill cranes have a variety of vocalizations, but have loud, unmistakable voices. Their trachea is long and forms a loop within the breastbone, making their voices quite powerful. Their calls can be described as a loud, rolling, musical rattle, or a repeated series of trumpeting “garoo-a-a-a” calls that can be heard at a distance of more than a mile.
What the cranes may be more famous for is their lively dancing displays. Their display is usually associated with a courtship ritual, but it can also be used in aggression, facilitating pair formation, and sexual synchronization. The dance includes bowing, skipping and jumping, and cranes will also pick up sticks and repeatedly throw them up in the air. When it occurs in a flock, the dance will start slowly with one bird, then as other birds join in, the tempo speeds up. It is certainly a remarkable sight.
The sandhill crane is sometimes confused with the great blue heron (Ardea herodias). Though they have similar appearances, there are a few key differences. Sandhill cranes fly with outstretched necks, while herons fly with their head and neck tucked back into an “S” shape. Sandhill cranes have a rapid upstroke when flying, and herons have a slow, steady flap. Cranes nest separately on the ground, while herons nest in rookeries, which are large colonies in the trees. Cranes also have a loud, trumpet-like call, whereas herons emit hoarse croaks.
Coyotes, bobcats, and eagles are some of the sandhill crane’s predators, but human influence also puts them at danger. Destruction of marshland for development and some agricultural practices continue to be a threat, especially in the Central Platte River Valley of Nebraska. Their shrinking available roosting space is threatening their populations, as well populations of other animals, including endangered whooping cranes and least terns.
Sandhill crane fossils dating back six million years have been found in Nebraska, making it the oldest bird species still living today