White-winged Nightjar Eleothreptus candicans Scientific name definitions

White-winged Nightjar is a small, sexually dimorphic caprimulgid of the open savannas of central South America. The extensive white in the wings and tail of the adult male is unmistakable, and is exhibited during display flights performed at small arenas during the breeding season. This striking visual display is largely at the expense of vocal communication, with the species lacking the far-carrying calls typical of many other nightbirds, and males instead producing a dull mechanical noise during display flights. In contrast, the female – which appears to carry out all the incubation, brooding and chick provisioning duties – lacks any white markings in the plumage, and is superficially similar to the female Sickle-winged Nightjar (Eleothreptus anomalus) or Little Nightjar (Setopagis parvula).

Although there are historical records from two additional localities in Brazil, White-winged Nightjar is currently known from only four sites in northern Bolivia, south central Brazil and eastern Paraguay. As a consequence of this restricted distribution, and the ongoing degradation of its cerrado habitat, the species is listed as Endangered on the IUCN Red List. Nevertheless, it is likely that the species persists undetected at other sites within the large area encompassed by existing localities, and the identification and survey of potentially suitable campo grassland sites remains a priority.

19–23 cm (1 Holyoak, D. T. (2001). Nightjars and Their Allies: The Caprimulgiformes. Oxford University Press, Oxford, UK. Close ); male 46–51 g. Sexually dimorphic. Upperparts and inner wing-coverts pale greyish brown, speckled, barred and streaked brown; boldly spotted blackish on crown, no nuchal collar; outer wing-coverts white, edged brown and boldly spotted blackish; scapulars greyish brown boldly marked blackish, inner webs generally buffish; broad pale buff submoustachial stripe; row of buffish spots around lower throat; breast  greyish brown tinged chestnut and tawny, barred and speckled brown; rest of underparts white. In flight, male has whitish wings and a largely white tail  ; female lacks white in plumage, has scapulars more boldly marked blackish  and has buffish underparts. Iris reddish brown or chestnut, bill generally blackish with dull pinkish base, legs and feet grey or pinkish grey. Female might be confused with Setopagis parvula, but latter is more patterned, with pale throat and distinctive pale spots on wing-coverts. Juvenile only very recently described: similar to adult but slightly browner and less greyish, with no white on wings and tail. Subadult males show less white in the wings and tail, with four outer primaries having white terminal spots, and only the outermost all dark (thus virtually adult-like), the others being barred cinnamon (2 López, B., Clay, R.P. and Lowen, J.C. (1998). A new plumage of the White-winged Nightjar Caprimulgus candicans (Aves: Caprimulgidae). Bull. Brit. Orn. Club. 118(3): 183-187. Close ).

N Bolivia (Beni Biological Station, in Beni) (5 Grim, T. and Šumbera, R. (2006). A new record of the endangered White-winged Nightjar (Eleothreptus candicans) from Beni, Bolivia. Wilson J. Orn. 118(1): 109–112. Close ), SC Brazil (Emas National Park, in SW Goiás) (6 Rodrigues, F.H.G., Hass, A., Marini-Filho, O.J., Guimarães, M.M. and Bagno, M.A. (1999). A new record of White-winged Nightjar Caprimulgus candicans in Emas National Park, Goiás, Brazil. Cotinga 11: 83–85. Close ), and E Paraguay (Mbaracayú Forest Nature Reserve, in Canindeyú; Laguna Blanca, in San Pedro) (7 Pople, R.G. (2003). The Ecology and Conservation of the White-winged Nightjar Caprimulgus candicans (Eleothreptus candicans). PhD thesis, University of Cambridge, Cambridge, UK. Close , 8 Anon. (2002). A new population of the White-winged Nightjar Caprimulgus candicans. World Birdwatch 24(3): 5. Close ). Historical records from Mato Grosso and São Paulo, in S Brazil.

Typically open grasslands with scattered trees (e.g. Tabebuia caraiba and Anadenanthera spp.) (9 Clay, R.P., López Lanús, B., Tobias, J.A., Lowen, J.C. and Mazar Barnett, J. (2000). The display of the White-winged Nightjar. J. Field Orn.. 71(4): 619-626. Close ) and bushes: dry open savannas, and open cerrado or grassland with scattered bushes, palms, termite mounds and anthills. Also in grasslands regenerating after fires. Avoids areas of tall grass; sometimes listed for Chaco woodland, but this seems extremely unlikely (1 Holyoak, D. T. (2001). Nightjars and Their Allies: The Caprimulgiformes. Oxford University Press, Oxford, UK. Close ). A lowland species, recorded from sea-level to 210 m.

Largely unknown, although may be migratory in parts of range.

Known to feed on beetles and moths. Forages low (1–2 m above ground) (1 Holyoak, D. T. (2001). Nightjars and Their Allies: The Caprimulgiformes. Oxford University Press, Oxford, UK. Close ) over hillsides, hilltops and cerrado, ­including burnt areas; flight typically slow and frequently interspersed by glides (1 Holyoak, D. T. (2001). Nightjars and Their Allies: The Caprimulgiformes. Oxford University Press, Oxford, UK. Close ). Also reported to flycatch from low perch (1 Holyoak, D. T. (2001). Nightjars and Their Allies: The Caprimulgiformes. Oxford University Press, Oxford, UK. Close ).

Territorial calls of male are soft, undulating whistles, “tshere-she-shew” given during aerial chases (9 Clay, R.P., López Lanús, B., Tobias, J.A., Lowen, J.C. and Mazar Barnett, J. (2000). The display of the White-winged Nightjar. J. Field Orn.. 71(4): 619-626. Close ); alarm calls include similar whistles and abrupt “eek” calls. Males defend territories (in Paraguay, often sited along ridges) c. 30–60 m in diameter, within which they display (only on cloudless moonlit nights, sometimes throughout the night in suitable conditions) from 1–3 areas each ≥ 10 m from a palm or other small tree, and containing a leafless vertical perch and (2–3 m away) a small anthill, which is always marginally lower than the perch (9 Clay, R.P., López Lanús, B., Tobias, J.A., Lowen, J.C. and Mazar Barnett, J. (2000). The display of the White-winged Nightjar. J. Field Orn.. 71(4): 619-626. Close ). Apparent clustering of display arenas on upper slopes of ridges suggests a lek-mating system or male aggregation due to the use of specialized habitats for mating (9 Clay, R.P., López Lanús, B., Tobias, J.A., Lowen, J.C. and Mazar Barnett, J. (2000). The display of the White-winged Nightjar. J. Field Orn.. 71(4): 619-626. Close , 10 Pople, R.G. (2014). Breeding biology of the White-winged Nightjar (Eleothreptus candicans) in eastern Paraguay. Revista Brasileira de Ornitologia. 22(2): 219–233. Close ). Mechanical wing noises, some of them somewhat toad-like (“grrrrrt’’), with a sharp “tk” on alighting (audible up to 200 m), given in butterfly-like display flight principally designed to display the stunning white parts of plumage (1 Holyoak, D. T. (2001). Nightjars and Their Allies: The Caprimulgiformes. Oxford University Press, Oxford, UK. Close ). Display flight initially passes from the perch to the anthill, then flies directly upwards c. 50 cm, before descending rapidly and looping back again to the perch, within a period of 4–6 seconds (9 Clay, R.P., López Lanús, B., Tobias, J.A., Lowen, J.C. and Mazar Barnett, J. (2000). The display of the White-winged Nightjar. J. Field Orn.. 71(4): 619-626. Close ).

Until recently, almost unknown; first nest found in 1997 (11 Clay, R., Mazar Barnett, J. and Esquivel, E. (2014). First description of the eggs, chick, and nest site of the White-winged Nightjar Eleothreptus candicans. Revista Brasileira de Ornitologia. 22(2): 215–218. Close ). In a study in E Paraguay during 1998–2001 male display recorded from late Aug to early Jan, and egg laying from mid Sept to mid Nov; eggs laid directly on the ground, often between grass tussocks; clutch 2 eggs, pale cream-beige with variable dark brown and mauve-grey speckles and blotches, size 27·7 mm × 21·0 mm on average (n = 14), weight 6·7 g when recently laid (n = 10); chick weight c. 5·2 g on day of hatching (n = 4); hatching success 86% (n = 14 eggs); incubation period 19 days; nestling period c. 19–20 days (10 Pople, R.G. (2014). Breeding biology of the White-winged Nightjar (Eleothreptus candicans) in eastern Paraguay. Revista Brasileira de Ornitologia. 22(2): 219–233. Close ). Downy chick dark brown with inconspicuous buffy-brown and cinnamon spots, the spotting being densest on the crown; flanks and vent paler grey-brown; iris dark brown; bill blackish (11 Clay, R., Mazar Barnett, J. and Esquivel, E. (2014). First description of the eggs, chick, and nest site of the White-winged Nightjar Eleothreptus candicans. Revista Brasileira de Ornitologia. 22(2): 215–218. Close ).

ENDANGERED. Population currently estimated at 600–1700 mature individuals within an overall range of 3100 km². Until fairly recently, considered Critically Endangered and known only from two museum specimens dating from 1820s (both from Brazil, from Cuiabá, Mato Grosso, and the holotype from E São Paulo) (1 Holyoak, D. T. (2001). Nightjars and Their Allies: The Caprimulgiformes. Oxford University Press, Oxford, UK. Close ). Known from just four localities. Considered not uncommon at Emas National Park (132,000 ha), SW Goiás, in Brazil in 1980s, with no evidence for any declines since then (12 Grim, T. and Šumbera, R. (2006). A new record of the Endangered White-winged Nightjar (Eleothreptus candicans) from Beni, Bolivia. Wilson J. Orn.. 118(1): 109-112. Close ) (despite relatively few records in 1990s), and legally protected in that country. Attempts to predict the occurrence of additional populations in Brazil using a species distribution model proved unsatisfactory (13 Marini, M. Â., M. Barbet-Massin, L. E. Lopes, and F. Jiguet (2010). Predicting the occurrence of rare Brazilian birds with species distribution models. Journal of Ornithology 151(4):857–866. Close ). Possibly fairly common at Aguará Ñu in Reserva Natural del Bosque Mbaracayú, E Paraguay, where up to 20 pairs discovered in suitable habitat (of which there is c. 8000 ha) Sept–Dec 1995; continued work in Jul–Nov 1997, involving marking and radio-tracking birds, gave estimated population of 40–150 birds. In Paraguay, also known from Laguna Blanca, San Pedro, and predicted to occur in Serranía San Luis National Park, Concepción (14 Robbins, M. B., R. C. Faucett, and N. H. Rice (1999). Avifauna of a Paraguayan cerrado locality: Parque Nacional Serranía San Luis, Depto. Concepción. Wilson Bulletin 111(2):216–228. Close ), but no records there to date. Male captured at Beni Biological Station in N Bolivia in Sept 1987 suggests possibility of a population in this area, although just one subsequent record there, in Sept 2003 (12 Grim, T. and Šumbera, R. (2006). A new record of the Endangered White-winged Nightjar (Eleothreptus candicans) from Beni, Bolivia. Wilson J. Orn.. 118(1): 109-112. Close ). Seriously threatened by loss of breeding habitat to agriculture and ranching, and to grass fires, often started deliberately.