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© 2003 Cornell Laboratory of Ornithology |
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Sandhill Crane Cool Fact: Sandhill Crane families (mother, father, and young) typically stay together for nine to ten months, until early in the spring after the young bird’s hatching.
Well known for their elaborate courtship dances and graceful flight, Sandhill Cranes are the most common and widespread crane in North America. Their assembly in huge numbers in central Nebraska during spring migration is one of North America’s great avian phenomena. The species, which includes multiple distinct populations on the continent, also shows fascinating family dynamics, including unusually durable pair bonds and extended parental care of young. Sandhill Cranes breed across the tundra, mountains, and plains of Canada and the northern United States, from western Alaska (and northeast Siberia) to central Ontario and Michigan. Isolated populations breed in northwest Colorado, at the Wyoming-Idaho border, in northern Nevada, and in southern Oregon and northeast California. Sandhill Cranes from all these regions are migratory, wintering in the Central Valley of California; southern Arizona, New Mexico, Texas, and Louisiana; south Florida; and northern Mexico. Sandhill Crane populations in southern Alabama and northeast Florida are resident year-round. These various populations show significant morphological differences, most obviously in size; Sandhill Cranes that breed in the Arctic (lesser sandhill cranes, or Grus canadensis canadensis) are smallest, and those nesting in the northern United States are the largest (greater sandhill crane, or G. c. tabida), with sizes of central Canadian and nonmigratory birds falling in between. Such differences have led ornithologists over recent decades to recognize at least three and up to six subspecies of Sandhill Crane. Sandhill Cranes forage by picking and probing with their long bills both at and below the water’s surface, as well as on land. They prefer grain when available, but eat a wide variety of foods. In their northern breeding areas, they consume berries, mammals, and insects. Where resident year-round, Sandhill Cranes eat insects, reptiles, amphibians, small birds and mammals, seeds, and berries. During migration, Sandhill Cranes assemble at established staging areas and stopover points. One such place, in the Platte and North Platte River valleys in Nebraska, hosts the largest gathering of cranes in the world. About three-fourths of the Sandhill Cranes that breed from Alaska and the Canadian plains and mountain provinces pass through the area. At its peak in late March, the number of Sandhill Cranes on the Platte and North Platte reaches about half a million. At the Nebraska staging area and elsewhere in early spring, Sandhill Cranes engage in dazzling courtship displays shortly after dawn. The primary mechanism for pair formation, courtship “dancing” includes raising bills, strutting, prancing, spreading wings, and leaping, with distinctive vocalizations. These acts are triggered by hormonal changes, which in turn result from changes in the duration of daylight. Nests are generally built above water, attached to emergent vegetation and/or actually floating on the surface. Floating nests have the advantage of remaining intact and accessible even with increases in water level. Some Sandhill Cranes build their nests on dry land; such nests are typically smaller than those built over water. Surrounding vegetation, such as twigs or grass, is used to construct the nest. Clutches usually include two eggs. Within 24 hours of hatching, Sandhill Crane chicks can walk from the nest; they can also swim. By the second day, siblings are highly aggressive toward each other; indeed, conflicts between siblings may be one important reason that most often, only one young crane per brood survives to fledging. Notwithstanding this intense sibling rivalry, Sandhill Cranes have close and durable pair bonds and family relationships. Pairs remain bonded and monogamous for periods of multiple years. Mother, father, and young stay together from the time of hatching into the following March, a period of nine to ten months. During this time, first-year birds feed on their own, but depend on their parents’ locating food and providing protection from predators and other territorially aggressive Sandhill Cranes. Description: Sandhill Cranes are tall, long-necked, heavy-bodied birds, measuring about 45 inches from bill tip to tail. Lesser Sandhill Cranes average about 10 percent shorter in height. During summer, adult Sandhill Cranes have rust-colored bodies, wings, and tails subtly shaded with gray; necks are entirely gray. In winter, rust coloration is mostly absent, replaced by pure gray. Variable amounts of reddish-brown may appear in the wings. In all seasons, legs and bills are black, and crown is red. Juvenile Sandhill Cranes have mostly rusty brown upperparts and gray underparts, with no red cap. Unlike herons and egrets, Sandhill Cranes and cranes of other species fly with their necks extended. (Cranes are thought to be more closely related to rails than to herons and egrets.) Sandhill Cranes have a distinctly hunchbacked appearance in flight. Sandhill Cranes also have a characteristic wingbeat, pushing slowly downward and then flicking quickly upward. Voice: Sandhill Cranes issue a variety of vocalizations, usually loudly. Most common are loud rattles and rolling trumpet-like calls covering multiple pitches at once. Recording credit: The recording of the Sandhill Crane was made by Marian P. McChesney, MLNS catalog #2764. Recordings of the Sandhill Crane may be found on our Bird Songs of Alaska, Bird Songs of California, Bird Songs Eastern/Central, and Western Bird Songs CDs and tapes available at our online Cornell Lab Birding Shop. Reference:
Tacha, T.C., S.A. Nesbitt, and P.A. Vohs. 1992. Sandhill Crane. In
The Birds of North America, No. 31 (A. Poole, P. Stettenheim, and F. Gill,
Eds.). Philadelphia: The Academy of Natural Sciences; Washington, DC:
The American Ornithologists’ Union. |
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Copyright © 2003 Cornell Laboratory of Ornithology |