(Gruidae)
Class: Aves
Order: Gruiformes
Suborder: Grues
Family: Gruidae
Thumbnail description
Large birds with long neck and legs, usually gray or white plumage
Size
35–70 in (90–176 cm); 4.4–26.5 lb (2–12 kg)
Number of genera, species
4 genera; 15 species
Habitat
Typically inhabit shallow wetlands from tropical areas to the Arctic
Conservation status
Vulnerable: 5; Endangered: 6
Distribution
Present in all regions except Antarctica and South America
Evolution and systematics
Cranes are an ancient family that dates back some 40–60 million years to the end of the Age of the Dinosaurs in the remote Eocene. More than a dozen extinct species are represented in fossil records.
The Gruidae's closest relative is the New World limpkin of the family Aramidae. Somewhat smaller than cranes, limpkins have an upright stance and loud calls reminiscent of cranes. The next closest relative to the cranes and limpkins are the New World trumpeters of the family Psophidae. Native to the tropical forests of South and Central America, the jumpy behavior and the plumage of trumpeters somewhat resembles that of the most primitive of cranes, the crowned cranes. These close links of cranes to New World families suggests that the pro-crane originated in the New World and subsequently expanded into Asia where their closest relatives are bustards of the family Otidae—a family that is restricted to the Old World. From Asia, ancient cranes probably extended their ranges into Africa and Australia.
Crowned cranes are placed in the subfamily Balearicinae, and differ from cranes of the subfamily Gruinae in many ways. Crowned cranes have loose plumage and the inability to tolerate extreme cold. Gruinae cranes have compact plumage and are cold-hardy. Balearicinae cranes have elongated hind toes (hallux) and perch in trees. Gruinae cranes have vestigial short hind toes and seldom perch in trees. As the name suggests, crowned cranes have elaborate bristle-like feathers on the hind part of their heads that look like golden crowns. While Gruinae cranes lack this plumage, portions of the heads of most species are covered by predominantly bare red skin that is used in display. The trachea of crowned cranes proceeds directly from the neck to the lungs in contrast to the trachea of the Gruinae that coils to varying degrees into the sternum. The prevalence of extinct species of crowned cranes in fossil records in North America, suggests that the Balearicinae or its ancestor gave rise to the Gruinae. Today there are two living species of Baleariciae, both of the genus Balearica and both restricted to wetlands amidst the grasslands and savannas of sub-Saharan Africa.
The Gruinae includes thirteen species of the typical cranes. Although comparative studies of their DNA by American scientist Dr. Carey Krajewski suggest they all can be considered members of a single genus Grus, the species are divided into three genera—Grus, Anthropoides, and Bugeranus—based on anatomical and behavioral evidence.
The Grus includes 10 species divided into four subgroups, the Siberian; the sandhill; the Group of Five (Eurasian, whooping, hooded, black-necked and red-crowned); and the Group of Three (brolga, sarus, and white-naped). Anthropoides includes demoiselle and blue cranes, while Bugeranus has the wattled crane.
The Siberian is the enigma of the Gruinae. Although resembling the whooping crane with glistening white plumage and black primary flight feathers, the red facial comb is restricted to the area in front of the eyes, giving it a nun-like look and a pattern somewhat similar to that of the comb of the wattled crane. The reduced coiling of its trachea and its feeding behavior is also similar to the wattleds. But these similarities with Bugeranus are perhaps the consequence of convergent evolution. DNA of the Siberian suggest the species is definitely a Grus but with a more distant relationship to the remaining nine species within that genus.
The sandhill has some behavioral links to Siberian cranes but more DNA, anatomical, and behavioral links to the Group of Three. Within the Group of Three, DNA suggests the white-naped of Asia and the brolga of Australia are more closely related to each other than to the sarus of south Asia. Anatomical evidence suggests the brolga and the sarus are more closely aliened. DNA suggests the red-crowned crane is most distant within the Group of Five, and that the Eurasian, whooping, hooded, and black-necked cranes are closely related to each other. Perhaps the whooping crane arose from a stock of Eurasian cranes that immigrated into North America from Asia.
DNA suggests that the wattled crane is closely related to the demoiselle and blue cranes. Wattled cranes are adapted to African wetlands while the Anthropoides species live predominantly in grasslands in southern Africa (blue) and in Asia and north Africa (demoiselle). Perhaps the demoiselle cranelike ancestor from Asia radiated into African wetlands and grasslands to become the wattled and the blue cranes.
Physical characteristics
Cranes are large, long-legged, long-necked birds that typically inhabit shallow wetlands. They have loud calls that can carry for several miles.
Distribution
Cranes occur on all continents except Antarctica and South America.
Habitat
Most cranes nest in wetlands, where they also feed. Many species use freshwater wetlands in their summer breeding areas, but may use saltwater coastal marshes in their wintering ranges. Two species of cranes predominantly inhabit grasslands.
Behavior
Cranes of northern latitudes migrate thousands of miles (kilometers) south to wintering areas. When prevailing winds are correct, cranes climb mid-morning thermals to glide. While gliding they are not in "V" formation. However, when flap-flying without the aid of thermals, they do fly in "V" formation. For each crane population there are usually one or two traditional staging areas where the cranes remain for several weeks during migration. Otherwise, when migrating, cranes fly until late in the afternoon or evening and then roost opportunistically at available wetlands. Juvenile cranes remain close to their parents during migration and throughout most of the winter. Sometimes they accompany their parents back to natal areas in spring, and sometimes they leave their parents before or during the spring migration.
Cranes that live in warm climates typically breed during the wet season or seasons and gather in flocks during the dry season. Flocking is usually greatest just before the onset of the next breeding season and is presumed to facilitate integration of juveniles in sub-adult flocks and genetic mixing as new pairs form in the flocks.
Resources
Books:Archibald, G.W. "Cranes and their Allies." In Encyclopedia of Birds: A Comprehensive Illustrated Guide by International Experts, 2nd ed. Edited by Joseph Forshaw. Sydney: UNSW Press Ltd., 1998. del Hoyo, J., A. Elliott, and J. Sargatal. Handbook of the Birds of the World. Vol. 3, Hoatzin to Auks. Barcelona: Lynx Edicions, 1996.
Meine, Curt D. and George W. Archibald, eds. The Cranes: Status Survey and Conservation Action Plan. Cambridge: IUCN Publication Services, 1996.
Sibley, C.G., and B.L. Monroe, Jr. Distribution and Taxonomy of Birds of the World. New Haven: Yale University Press, 1990.
Periodicals:Horwich, Robert H. "Use of Surrogate Parental Models and Age Periods in a Successful Release of Hand-Reared Sandhill Cranes." Zoo Biology 8 (1989): 379–90.
Krajewski, Carey. "Phylogenetic Relationships Among Cranes (Gruiformes: Gruidae) Based on DNA Hybridization." Auk 106 (1989): 603–18.
Wessling, Bernhard. "Individual Recognition of Cranes, Monitoring and Vocal Communication Analysis by Sonography." IV European Crane Workshop. European Crane Working Group, 2000.
Organizations:International Crane Foundation. P.O. Box 447, Baraboo, WI 53913-0447 USA. Phone: (608) 356-9462. Fax: (608) 356-9465. E-mail: explorer@savingcranes.org Web site:
[Article by: George William Archibald, PhD]
