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Crane Hawk
Geranospiza caerulescens

Status: Lower risk

Population Trend: Unknown.

Other Names: Banded Crane Hawk (gracilis), Black Crane Hawk (nigra), Black Frog Hawk, Blackish Crane Hawk (nigra), Crane-hawk, Ischnosceles, Gray Crane Hawk (caerulescens), Wood Hawk.

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Geranospiza caerulescens
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Distribution: Neotropical. Northern MEXICO south through lowlands of Central and South America west of the Andes to northwestern PERU and through the Amazon Basin and east of the Andes to northern ARGENTINA. more....

Subspecies: 6 races. G. c. livens: Northwestern MEXICO (Sonora); G. c. nigra: Northern MEXICO (Sinaloa and Tamaulipas) south to PANAMA (west of Canal); G. c. balzarensis: PANAMA (east of Canal) to western COLOMBIA, western ECUADOR, and northwestern PERU; G. c. caerulescens: Eastern slopes of COLOMBIA and ECUADOR to the GUIANAS, Amazonian PERU, and BRAZIL; G. c. gracilis: Northeastern BRAZIL (Maranhão, Ceará, and Piauí to central Goiás and Bahia); G. c. flexipes: Southern BRAZIL (Minas Gerais, southern Goias, and Mato Grosso) and BOLIVIA south through PARAGUAY and URUGUAY to north-central ARGENTINA. more....

Taxonomy: The Crane Hawk was formerly split into several separate species, including the nigra group (containing livens and balzarensis)), the caerulescens group, and the gracilis group (including flexipes) (Peters 1931). However, color varies clinally in this species (Amadon 1982), and recent authors have regarded the group as comprising a single species. Because of the similarity in morphology and feeding habits between this species and the two species of the African genus Polyboroides. Friedmann (1950) hypothesized that they are closely related, but subsequent authors (e.g., Burton 1978) concluded that the similarities were due to convergent evolution, since the evidence for a close relationship between the two groups was weak, if the similarities of the hind limb were discounted. The study of Lerner and Mindell (2005), based on molecular sequences from two mitochondrial genes and one nuclear intron, showed that this species is probably allied to the Neotropical buteonines, as suggested earlier by Amadon (1982) on morphological grounds. More recently, Amaral et al. (2009) concluded that this species belongs to a clade also containing Rostrhamus sociabilis and Geranospiza caerulescens, based on more detailed studies with mitochondrial and nuclear genes. This clade is sister to all other buteonines, except for Ictinia and Butastur. more....

Movements: Irruptive or local migrant (Bildstein 2006), probably moving in response to changing water conditions.

Habitat and Habits: Occurs in tropical lowlands at the edge of forested areas, including gallery forest, várzea forest, wooded swamps, mangroves, and savannas with ponds. Usually, but not always, associated with water. Often perches at forest edge, soars low over adjacent open areas between forest patches, or circles at higher altitudes over forest. Usually occurs singly and is often unwary (Howell 1957).more....

Food and Feeding Behavior: These hawks forage by dropping from a perch to capture prey on the ground, by running or walking along branches, peering into holes and arboreal vegetation, or even running along the ground in more open areas, and they may quarter over open areas like a harrier (Dickey and van Rossem 1938, Sutton 1954, Jehl 1968). They often hang from a branch, balancing themselves by flapping and with spread wings and tail. Like the African harrier hawks (Polyboroides spp.), Crane Hawks can bend their legs backward and forward at the tarsal joint, an adaptation for extracting prey from tree cavities, crevices, or clumps of bromeliads and other epiphytes (Burton 1978, Smeenk and Smeenk-Enserink 1983). Sutter et al. (2001) made the only detailed study of the feeding habits of this species. They found that nesting birds at Tikal National Park, Guatemala fed on a wide variety of small vertebrates, including rodents, bats, small carnivores, lizards, snakes, and small birds. Other researchers have reported large insects and other arthropods, nestling birds, and snails in the diet (Jehl 1968, Alvarez del Toro 1980). more....

Breeding: Nests are placed high in trees and are often in clumps of orchids or other epiphytes. The nest is a small, somewhat flimsy, shallow cup of twigs, lined with finer twigs, including some with green leaves, and placed in a crotch 10-25 m high in a tree (Hewitt 1937, Sutton 1954, Wetmore 1965). Clutch size is is usually 2 eggs, sometimes 1, and they are unmarked dull white eggs, which may have a bluish tinge. more....

Conservation: Nowhere particularly common, but widely distributed and probably adaptable to a certain amount of habitat modification if wet areas are not totally eliminated. Categorized as a species of "Least Concern" by BirdLife International. more....

Important References: 
Bierregaard, R.O. 1994. Crane Hawk. P. 168 in del Hoyo, J., A. Elliott,
  and J. Sargatal (eds). Handbook of birds of the world. Vol. 2. New World
  vultures to guineafowl. Lynx Edicions, Barcelona, Spain.
Burton, P.J.K. 1978. The intertarsal joint of the harrier-hawks,
  Polyboroides spp. and the Crane-hawk Geranospiza caerulescens. Ibis
  120:171-177.
Ferguson-Lees, J., and D.A. Christie. 2001. Raptors of the world. Houghton
  Mifflin, Boston, MA.
Haverschmidt, F. 1964. Nesting of the Crane Hawk in Surinam. Condor
  66:303-305.
Jehl, Jr., J.R. 1968. Foraging behavior of Geranospiza nigra, the Blackish
  Crane-hawk. Auk 85:493-494.
Lerner, H.R., and D.P. Mindell. 2005. Phylogeny of eagles, Old World
  vultures, and other Accipitridae based on nuclear and mitochondrial DNA.
  Molecular Phylogenetics and Evolution 37:327-346.
Olmos, F. 1990. Harrier-like hunting behaviour by a Crane Hawk Geranospiza
  caerulescens
. Bulletin of the British Ornithologists' Club 110:225-226.
Ouellet, H. 1991. Description of the courtship and copulation behavior or
  the crane-hawk. Journal of Field Ornithology 62:403-406.
Smeenk, B., and N. Smeenk-Enserink. 1983. Observations on the Harrier Hawk
  Polyboroides typus in Nigeria, with comparative notes on the Neotropical
  Crane Hawk Geranospiza caerulescens. Ardea 71:133-143.
Sutter, J. 1999. Ecology of the Crane Hawk (Geranospiza caerulescens) in
  Tikal National Park, Guatemala. M.Sc. thesis, Boise State University, Boise,
  Idaho.
Sutter, J. 2012. Crane Hawk. Pp. 104-119 in D.f. Whitacre (ed.),
  Neotropical birds of prey: biology and ecology of a forest raptor community.
  Cornell University Press, Ithaca, NY.
Sutter, J., W.E. Martinez, Oliva T., F., N. Oswaldo J., and D.F. Whitacre.
  2001. Diet and hunting behavior of the Crane Hawk in Tikal National Park,
  Guatemala. Condor 103:70-77.
more....

Sites of Interest:
VIREO
Crane Hawk photos.
Xeno-canto
Vocalizations.
Aves de Rapina do Brasil
Species account with emphasis on Brazil.

Researchers:
Gómez, César

Last modified: 7/27/2012

Recommended Citation: Global Raptor Information Network. 2014. Species account: Crane Hawk Geranospiza caerulescens. Downloaded from http://www.globalraptors.org on 16 Apr. 2014








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