Long-winged Harrier Circus buffoni Scientific name definitions

The Long-winged Harrier is a striking, lanky raptor of South American grasslands. The male has largely black upperparts, a gray tail and gray remiges boldly banded with black, and white facial markings. The light morph has a white belly, while the dark morph is entirely black below. Females are similarly-patterned, with much of the black replaced by brown. This species is found in wet fields, marshes, grasslands, and savanna where it courses low over the grass and drops to the ground to capture mammals, reptiles, amphibians, and birds. Like other harriers, it nests on the ground in grasses. It ranges from central Argentina, where birds are present only during the summer breeding season, through eastern Brazil to the Guianas, Venezuela, and Colombia. Its status in the northern parts of the range is unclear, but breeding has been documented on Trinidad.

46–60 cm (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ); male 390–464 g (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ), female 400–645 g (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ); wingspan 119–155 cm (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ). Female averages 4% larger, but largest female can be 30% larger than smallest male; also some evidence of clinal size variation, increasing N–S (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ). Particularly long wings and tail, white rump; like other Circus, wings held in slight dihedral in coursing flight; has longer wings and more buoyant flight than sympatric congeners. Polymorphic, with melanistic morph (not uncommon in N of range and C Argentina at least (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ) ). Normal morph male has head and back black, with white supercilium and white dap­pling on throat; below white with black breastband; underwing pale brownish grey, with black barring and black wingtips; tail grey with white tip and blackish bands, above wing-coverts and flight feathers grey, remiges tipped black. Female like male, but brown above, with tawny dappling on throat, brown streaking ventrally and tawny thighs; slightly larger than male. Melanistic morph (both sexes) has sooty black body  and white rump; tail, primaries and underwing as in normal colour morph. Legs and feet pale orange-yellow. Immature  , normal morph, as normal morph female, but underparts more broadly streaked brown; dark morph similar to adults, but sooty with white streaking below, thighs and undertail-coverts rufous.

Colombia E to the Guianas, Trinidad, and S to Brazil, Paraguay, N & C Argentina and Uruguay; non-breeding visitor in Bolivia and N Brazil; also recorded in E Panama (2 Angehr, G.R. (2011). First North American records of Long-winged Harrier (Circus buffoni), Large-billed Seed-finch (Oryzoborus crassirostris), and Yellow-hooded Blackbird (Chrysomus icterocephalus) from Panama. North Amer. Birds 64(4): 540–547. Close ).

Lowland tropical zone, in open fields including cultivated areas such as wheat (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ), rice fields (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ), marshes, grassland and savanna, but most numerous in natural grassland (3 Pedrana, J., J. P. Isacch, and M. S. Bó (2008). Habitat relationships of diurnal raptors at local and landscape scales in southern temperate grasslands of Argentina. Emu 108(4):301-310. Close ); usually moderately wet areas , but occasionally found in rather drier environments, even in the vicinity of wooded areas, in non-breeding season (4 Souza Petersen, E., M. V. Petry, and L. Krüger-Garcia (2011). Utilização de diferentes hábitats por aves de rapina no sul do Brasil. Revista Brasileira de Ornitologia 19(3):376-384. Close ). Normally below 690 m, but one record at 2000 m in Argentina; 300–1000 m in Colombia.

Migratory, at least in southernmost populations; insufficient data to assess status (resident, migratory or wintering) throughout Brazilian distribution, but recently recorded very late in austral spring in Rondônia (5 Kirwan, G.M. and Shirihai, H. (2007). Notes on open-country birds in the Brazilian states of Rondônia and Pará. Cotinga. 29: 178–180. Close ). Very rare visitor to SE Peru, presumably as an austral winter visitor (6 Schulenberg, T. S., D. F. Stotz, D. F. Lane, J. P. O’Neill, and T. A. Parker (2007). Birds of Peru. Princeton University Press, Princeton, NJ, USA. Close ). Presumed to breed Llanos do Moxos, S Beni, Bolivia (7 Tobias, J.A. and Seddon, N. (2007). Nine bird species new to Bolivia and notes on other significant records. Bulletin Brit Orn. Club 127(1): 49–84. Close ), but perhaps only a visitor further N and W in the country, e.g. in SC Pando (7 Tobias, J.A. and Seddon, N. (2007). Nine bird species new to Bolivia and notes on other significant records. Bulletin Brit Orn. Club 127(1): 49–84. Close ), with some evidence of passage through Santa Cruz in Oct–Nov (8 Olivo, C. (2005). Cold fronts and raptor migration in Bolivia. Orn. Neotropical. 16(1): 109–115. Close ). Further S, in E Buenos Aires (Argentina), passage has also been noted, peaking in early Oct (9 Juhant, M. A. (2010). Austral spring migration counts of raptors in Punta Rasa, Argentina. Ornitologia Neotropical 21(2):263–270. Close ). Birds in N South America were thought to be all migrants from S, but breeding record from Trinidad (where mainly recorded Dec–Aug (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ) ) and records of food-passing in Surinam (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ) suggest that others may breed in appropriate habitat in this region. Records from Pacific slope of SW Colombia (10 Alvarez-López, H. and G. H. Kattan (1995). Notes on the conservation status of resident diurnal raptors of the middle Cauca Valley, Colombia. Bird Conservation International. 5(2–3):341–348. Close ) and Chile suggest species may occasionally cross Andes. Occasional visitor to Santa Cruz province, S Argentina (11 Darrieu, C. A., A. R. Camperi, and S. Imberti (2008). Avifauna (non Passeriformes) of Santa Cruz province, Patagonia (Argentina): annotated list of species. Revista del Museo Argentino de Ciencias Naturales 10:111–145. Close ) and Tierra del Fuego; recently recorded on Falkland Is (12 Gregory, P. (1994) Notes on new and scarce birds in the Falkland Islands 1988–1990. Bulletin of the British Ornithologists' Club 114: 12–20. Close ).

Birds  (both aquatic and terrestrial including various smaller Rallidae (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ) ), reptiles (especially lizards (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ) ), frogs and small mammals (including cavies Cavia (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ) ); principal prey in Surinam seems to be mammals, but two birds seen eating eggs at a heronry, and has also been recorded taking entire nest of a Fluvicola water-tyrant (Tyrannidae) (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ). Hunts by coursing over open country in typical style of harriers, usually less than 5 m above ground (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ).

Apparently only very vocal in nest defence when gives a rapid wader-like chattering; plaintive disyllabic squeal given in courtship or when soliciting food (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ).

Eggs in Jun, Trinidad; possible nest building in Aug, Colombia; season Sept–Jan, C Argentina, and at least Dec–Jan, Surinam (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ). Nest a platform of rushes and grasses (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ) on the ground in rushes or up to 3 m above ground and sometimes in up to 75 cm of standing water (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ); dimensions 40–65 cm across and 10–30 cm deep (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ). 3–4 eggs in Argentina; 2 eggs in Trinidad. The brood parasite, Black-headed Duck (Heteronetta atricapillus) eggs have been found in this species nests in Argentina (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ). No further information available.

Not globally threatened (Least Concern). CITES II. Widespread, but apparently rather local. Very poorly known. Rare and local in E Brazil, more frequent in S Brazil. In Colombia, fairly common in NE Meta, less numerous in W Meta, rare in Cauca Valley. Likely to be affected by degradation of wetland habitats.