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sandhill crane
Florida Sandhill Crane,
Grus canadensis pratensis.
Adult (behind) and immature
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Subclass: Neornithes
Infraclass: Neognathae
Superorder: Neoaves
Order: Gruiformes
Family: Gruidae
Genus: Grus
Species: G. canadensis
Binomial name
Grus canadensis
(Linnaeus, 1758)
subspecies
  • Grus canadensis canadensis
(Linnaeus, 1758)
  • Grus canadensis pratensis
(F.A.A. Meyer, 1794)
  • Grus canadensis nesiotes
Bangs & Zappey, 1905
  • Grus canadensis tabida
(J.L. Peters, 1925)
  • Grus canadensis rowani (disputed)
Walkinshaw, 1965
  • Grus canadensis pulla
Aldrich, 1972

and see text

Synonyms

Ardea canadensis Linnaeus, 1758
Grus minor
Grus proavus
and see text

The Sandhill Crane (Grus canadensis) is a large crane of North America and extreme northeastern Siberia. The common name of this bird references habitat like that at the Platte River, on the edge of Nebraska's Sandhills in the American midwest. This is the most important stopover area for the Lesser Sandhill Crane, (Grus canadensis canadensis), with up to 450,000 of these birds migrating through annually.

Contents

Description

Head of adult Grus (canadensis) canadensis

Adults are gray overall; during breeding, the plumage is usually much worn and stained, particularly in the migratory populations, and looks nearly ochre. The sandhill crane has a red forehead, white cheeks and a long dark pointed bill. Its long dark legs trail behind in flight, and the long neck is kept straight in flight. Immature birds have reddish brown upperparts and gray underparts. The sexes look alike. Size varies among the different subspecies. This crane frequently gives a loud trumpeting call that suggests a French-style "r" rolled in the throat, and they can be heard from a long distance.

Mated pairs of cranes engage in "unison calling." The cranes stand close together, calling in a synchronized and complex duet. The female makes two calls for every single call of the male.

The only other large grayish-bodied bird of North America is the Great Blue Heron. This heron is of similar dimensions to the Sandhill Crane and is sometimes mistakenly called a crane, even though it is very different in plumage details and build. Like other herons, it flies with its neck tucked toward the body.

The sandhill crane's large wingspan, which is 6-8 feet when fully grown, makes this a very skilled soaring bird similar in style to hawks and eagles. Utilizing thermals to obtain lift, they can stay aloft for many hours, requiring only occasional flapping of their wings and consequently expending little energy. With migratory flocks containing hundreds of birds, they can create clear outlines of the normally invisible rising columns of air (thermals) that they ride.

It has been said that Sandhill Cranes have been spotted devouring their young if the parents recognize weakness in a young bird. This seems unlikely. Cranes do devour the young of other species, like ducklings, especially when they are raising crane colts. However, cranes are gentle to their own injured colts and attentive to the corpses of their young. [1]

The Sandhill Crane flies south for the winter. In their wintering areas they form flocks of over 10,000 birds. One place to observe this is at Bosque del Apache National Wildlife Refuge, 100 miles south of Albuquerque, New Mexico. There is an annual Sandhill Crane Festival in November.

Fossil record

The Sandhill Crane has one of the longest fossil histories of any extant bird.[2] A 10-million-year-old crane fossil from Nebraska is often cited as being of this species,[3] but this is more likely from a prehistoric relative or the direct ancestor of the Sandhill Crane and may not belong in the genus Grus. The oldest unequivocal Sandhill Crane fossil is "just" 2.5 million years old,[4] over one and a half times older than the earliest remains of most living species of birds, which are primarily found from after the Pliocene/Pleistocene boundary some 1.8 million years ago. As these ancient Sandhill Cranes varied as much in size as the present-day birds, even those Pliocene fossils were sometimes described as new species.[5] Grus haydeni on the other hand may or may not have been a prehistoric relative of the living species, or it may actually comprise material of the Sandhill Crane and its ancestor.[6]

Head of adult Sandhill crane (Grus canadensis canadensis)
George C. Reifel Migratory Bird Sanctuary, Ladner, British Columbia

Subspecies and evolution

There is considerable variation in size (much of which is clinal) and in migratory habits. A male of G. c. canadensis averages 7.4 lbs (3.34 kg), 39 in (98 cm) in length and has a wingspan of 5.3 ft (1.6 m). A male of G. c. tabida averages 11 lbs (5 kg), 47 in (119 cm) in length and has a wingspan of 7 ft (2.12 m). The southern subspecies (along with G. c. rowani) are intermediate, roughly according to Bergmann's Rule.

Three subspecies are resident; pulla of the Gulf Coast of the U.S., pratensis of Florida and Georgia and nesiotes of Cuba.[7] The northern populations exist as fragmented remains in the contiguous U.S. and a large and contiguous population from Canada to Beringia. These migrate to the southwestern United States and Mexico. This crane is a rare vagrant to China, South Korea and Japan and a very rare vagrant to western Europe.

Six subspecies have been recognized in recent times:

  • Lesser Sandhill Crane, Grus canadensis canadensis
  • Cuban Sandhill Crane, Grus canadensis nesiotesESA: Endangered
  • Florida Sandhill Crane, Grus canadensis pratensisESA: Endangered
  • Mississippi Sandhill Crane, Grus canadensis pulla – ESA: Endangered
  • Canadian Sandhill Crane, Grus canadensis rowani
  • Greater Sandhill Crane, Grus canadensis tabida

The Canadian Sandhill Crane is morphologically not reliably distinct and was never unequivocally accepted as valid subspecies.[8] The other can be somewhat more reliably distinguished in hand by measurements and plumage details, apart from the size differences already mentioned. Unequivocal identification often requires location information, which is often impossible in migrating birds.

Lesser Sandhill Crane (Grus canadensis canadensis)
George C. Reifel Migratory Bird Sanctuary, Ladner, British Columbia

Analysis of control region mtDNA haplotype data shows 2 major lineages, one including the Lesser Sandhill Crane or Little Brown Crane, the Arctic and the subarctic migratory population. The other lineages can be divided into a migratory and some indistinct clusters which can be matched to the resident subspecies. The Lesser and Greater Sandhill Cranes are quite distinct, their divergence dating roughly to some time during the Late Pliocene or Early Pleistocene, some 2.3–1.2 million years ago (mya). It seems as if glaciation fragmented off a founder population of the Lesser Sandhill Crane, because during each major ice age its present breeding range was frozen year-round. Still, Sandhill Cranes are amply documented from fossil and subfossil remains right to the modern era.[9] Conceivably, they might be considered distinct species already, a monotypic G. canadensis and the Greater Sandhill Crane G. pratensis, which would include the other populations.[7]

It appears as if the scant differences between southern Canadian and western U.S. populations result from genetic drift due to the recent reduction in population and range fragmentation; until the early 20th century the southern migratory birds occupied a much larger and continuous range. Thus, the subspecies rowani may well be abandoned.[7]

The two southern U.S. resident populations are somewhat more distinct, while the Cuban population has been comparatively little studied but appears to have been established on the island for a long time. These and the migratory Greater Sandhill Crane proper form a group of lineages that diverged much more recently from a range in the southern U.S. and maybe northern Mexico, where they would have been resident. The southern migratory population would then represent a later re-expansion which (re-)evolved their migratory habits independent from the northernmost birds, the geographically separated populations expanding rapidly in numbers when more habitat was available as the last ice age ended.[7]

Distribution and ecology

Sandhill Crane colt

Their breeding habitat is marshes and bogs in central and northern Canada, Alaska, part of the midwestern and southeastern United States, Siberia and Cuba. They nest in marsh vegetation or on the ground close to water. The female lays two eggs on a mound of vegetation, but it is rare that both chicks hatch and grow to independence.[7] Cranes mate for life; both parents feed the young, called "colts", who are soon able to feed themselves. The colts are taught to fly over many weeks when they run and dance with their parents. Dancing is a significant component in the education of young cranes.[10] The Sandhill Crane does not breed until it is two to seven years old, and the average generation time is 12.5 years.[7] It can live up to 25 years in the wild; in captivity it has been known to live more than twice that span. Mated pairs stay together year-round and migrate south as a group with their offspring.

Eggs and nestling cranes are eaten by crows, ravens, canids, hawks, eagles, and raccoons. Adult cranes are preyed on by foxes, coyotes, eagles, wolves, bobcats, and large owls. When approached by an avian predator, sandhill cranes will fly at the predator, kicking at it with their feet. When aware of a mammalian predator, sandhill cranes move toward the predator with their wings spread and their bill pointed at the predator. If the predator persists, sandhill cranes will attack, hissing, stabbing with their bills and kicking with their feet.[11] The cranes tend to be more aggressive while protecting their young. Mammalian predators are generally more likely to prey on adult cranes while they are distracted by nesting.

Flock of Sandhill Cranes in central Nebraska

These birds forage while walking in shallow water or in fields, sometimes probing with their bills. They are omnivorous, eating insects, aquatic plants and animals, rodents, seeds and berries. Outside of the nesting season, they forage in large flocks, often in cultivated areas. In many western states and provinces of Canada, Sandhill Cranes are hunted during waterfowl seasons. The meat is reportedly among the better-tasting gamebirds.[12]

The Florida subspecies is often seen in residential yards, and these birds seem little afraid of human approach. These visitors will eat shelled corn and commercially purchased bird seed from the ground and from feeders. They may be seen in yards in north-central Florida virtually year-round, often in pairs that may be accompanied by a juvenile. Myakka River State Park, just 50 miles south of Tampa, is a wonderful site to observe them although all around central Florida you may see them in empty farm fields from November to February.

Status and conservation

Bosque del Apache NWR, NM

Though the Sandhill Crane is not considered threatened as a species, the three southernmost subspecies are quite rare. While the migratory birds could at least choose secure breeding habitat, the resident populations could not, and many subpopulations were destroyed by hunting or habitat change. However, initially the Greater Sandhill crane proper suffered most from persecution; by 1940 probably fewer than 1,000 birds remained. They have since increased greatly again, though with nearly 100,000 individuals they are still less plentiful than the Lesser Sandhill Crane, which numbers over 400,000 individuals, making the species the most plentiful crane alive today.[13]

The Florida Sandhill Crane is far less common, with some 5,000 individuals remaining. They are most threatened by habitat destruction and probably depend on human management in the long run. In Florida, it is protected, and if killed, carries a very high monetary penalty. This subspecies is under protection of state and federal law at this time. Since the loss of habitat is a somewhat controllable cause of a declining population, habitat preservation is a valuable management measure. The current outlook for the Florida sandhill crane, if it can be maintained on the protected habitats, is good. Transplanting wild birds, as well as introducing captive-reared birds into suitable areas where crane numbers are low, appears to be a viable technique in the management of this threatened species. It is hoped that these management strategies, plus continued ecological research, will prevent the Florida sandhill crane from reaching a more critical status.[14]

The Mississippi Sandhill Crane has most drastically declined in range; it used to occur along most of the northern Gulf of Mexico coast and its range was at one time nearly parapatric with that of its eastern neighbor (compare the Mottled Duck); today only 25 breeding pairs exist in an intensively managed population, but this seems at least stable in recent times. Some 300 Cuban Sandhill Cranes remain; this is the least-known of the populations.[13]

The Mississippi Sandhill Crane has become the first bird to have a young hatched where an egg was fertilized by a sperm that was previously thawed out from a cryogenic state. This occurred at the Audubon Institute as part of this subspecies' Recovery Plan.

Sandhill Cranes have been used as foster parents for Whooping Crane eggs and young in reintroduction schemes for that species. This project failed as these foster-raised Whooping Cranes imprinted on their foster parents and later did not recognize other Whooping Cranes as their conspecifics – attempting instead, unsuccessfully, to pair with Sandhill Cranes.

Gallery

See also

Footnotes

  1. ^ http://www.alaska-sandhill-crane-blog.com
  2. ^ Quantic & Hafen (2003): p.84
  3. ^ E.g. The Nature Conservancy: Sandhill Crane. Retrieved 2008-JAN-16.
  4. ^ Volz (2003)
  5. ^ Miller (1944)
  6. ^ Miller & Sibley (1942), Brodkorb (1967)
  7. ^ a b c d e f Rhymer et al. (2001)
  8. ^ Tacha et al. (1992)
  9. ^ Brodkorb (1967): pp152-153
  10. ^ http://www.christyyuncker.com/ColtSchooling.html
  11. ^ http://animaldiversity.ummz.umich.edu/site/accounts/information/Grus_canadensis.html
  12. ^ "Sandhill Crane". Kansas Department of Wildlife and Parks. http://www.kdwp.state.ks.us/news/Hunting/Migratory-Birds/Sandhill-Crane. Retrieved 14 December 2009. 
  13. ^ a b Archibald & Meine (1996), Rhymer et al. (2001)
  14. ^ Stys (1994).

References

  • Archibald, George W. & Meine, Curt (1996): 7. Sandhill Crane. In: del Hoyo, Josep; Elliott, Andrew & Sargatal, Jordi (eds.): Handbook of Birds of the World (Volume 3: Hoatzin to Auks): 85, plate 5. Lynx Edicions, Barcelona. ISBN 84-87334-20-2
  • BirdLife International (2004). Grus canadensis. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 May 2006. Database entry includes justification for why this species is of least concern
  • Brodkorb, Pierce (1967): Catalogue of Fossil Birds: Part 3 (Ralliformes, Ichthyornithiformes, Charadriiformes). Bulletin of the Florida State Museum 11(3): 99-220. PDF or JPEG fulltext
  • Meine, Curt D. & Archibald, George W. (eds.) (1996): Sandhill Crane (Grus canadensis). In: The cranes: - Status survey and conservation action plan. IUCN, Gland, Switzerland, and Cambridge, U.K.
  • Miller, Alden H. & Sibley, Charles Gald (1942): A New Species of Crane from the Pliocene of California. Condor 44(3): 126-127. DjVu fulltext PDF fulltext
  • Miller, Loye H. (1944): Some Pliocene birds from Oregon and Idaho. Condor 46(1): 25-32. doi:10.2307/1364248 DjVu fulltext PDF fulltext
  • Quantic, Diane Dufva; Hafen, P. Jane (2003): A Great Plains Reader. University of Nebraska Press. ISBN 0803238029
  • Rhymer, Judith M.; Fain, Matthew G.; Austin, Jane E.; Johnson, Douglas H. & Krajewski, Carey (2001): Mitochondrial phylogeography, subspecific taxonomy, and conservation genetics of sandhill cranes (Grus canadensis; Aves: Gruidae). Conservation Genetics 2(3): 203–218. doi:10.1023/A:1012203532300 PDF fulltext
  • Stys, B. (1994): Ecology and habitat protection needs of Florida sandhill cranes on areas proposed for land conversion activities. Florida Game and Fresh Water Fish Commission. Nongame Wildlife Program Technical Report No. 14. Tallahassee, FL. 27pp.
  • Tacha, T.C.; Nesbitt, S.A.; Vohs, P.A. (1992): Sandhill Crane. In: Poole, A. & Gill, F. (eds.): The Birds of North America 31: 1-24. Academy of Natural Sciences, Philadelphia, PA & American Ornithologists' Union, Washington, D.C. Online version. doi:10.2173/bna.31 (requires subscription) HTML introduction
  • Volz, Becky Lauren Volz (2003): The Biogeography of the Sandhill Crane (Grus canadensis). Version of 2003-DEC-31. Retrieved 2008-JAN-16.
  • Stys, B. 1994. Ecology and habitat protection needs of Florida sandhill cranes on areas proposed for land conversion activities. Florida Game and Fresh Water Fish Commission. Nongame Wildlife Program Technical Report No. 14. Tallahassee, FL. 27pp.

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