Sickle-winged Nightjar

The sickle-winged nightjar (''Eleothreptus anomalus'') is a species of nightjar in the family Caprimulgidae. It is found in Argentina, Brazil, Paraguay and possibly Uruguay.Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, A. Jaramillo, D. F. Lane, J. F. Pacheco, M. B. Robbins, F. G. Stiles, and K. J. Zimmer. Version 24 August 2021. Species Lists of Birds for South American Countries and Territories. https://www.museum.lsu.edu/~Remsen/SACCCountryLists.htm retrieved August 24, 2021

Taxonomy and systematics

The sickle-winged nightjar was described as ''Amblypterus anomalus'' which was later lumped into genus ''Caprimulgus''. Since the early 2010s it has been placed in its current genus ''Eleothreptus'', which it shares with the white-winged nightjar (''E. candicans''). It is monotypic.Young, N. (2020). Sickle-winged Nightjar (''Eleothreptus anomalus''), version 1.0. In Birds of the World (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.siwnig1.01 retrieved October 9, 2021Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, A. Jaramillo, D. F. Lane, J. F. Pacheco, M. B. Robbins, F. G. Stiles, and K. J. Zimmer. Version 24 August 2021. A classification of the bird species of South America. American Ornithological Society. https://www.museum.lsu.edu/~Remsen/SACCBaseline.htm retrieved August 24, 2021

Description

The sickle-winged nightjar is long; one male weighed . The adult male's upperparts are grayish brown spotted with dark shades of brown. The wings have a hooked "sickle" appearance due to the shape of the primary flight feathers. They are generally grayish brown, with blackish brown, cinnamon, and white markings. The chin is buffish white with brown bars; the throat brown with a cinnamon tinge, brown bars, and buffy streaks; the breast brown with buff spots and streaks; and the belly and flanks pale buff with brown bars. The adult female is browner than the male and does not have the modified primaries. The pattern and shades of the spots and bars are somewhat differerent as well. Juveniles are similar to the female, with a cinnamon tinge to the upperparts.

Distribution and habitat

The sickle-winged nightjar's distribution is not fully understood. It is documented in northeastern Argentina, southern Paraguay, and southern Brazil. It is suspected to also inhabit Uruguay but there are no documented records there, and there are sight records from further north in Brazil than the documented range. It is believed to be resident in most or all of its range but there are suggestions that it migrates north from Argentina following the breeding season.

Behavior

Feeding

The sickle-winged nightjar is crepuscular and nocturnal. It forages by sallying from the ground and possibly during low continuous flight. Between sallies it sits on roads and trails or perches on low branches or wire fence. It flies " with slow, fluttering flaps and glides". Its prey is insects though the details are unknown.

Breeding

The sickle-winged nightjar's breeding season appears to span from August to November or later, based on the dates of observation of adults in breeding condition, eggs, and young. It is assumed to lay its eggs on the ground without a nest like other nightjars.

Vocalization

One description of the sickle-winged nightjar's song is "a series of soft ''chip'', ''tchup'', or ''tchut'' notes"; another is "some chirping, cricket-like sounds" and a third is "a soft, single ''tick''". A reported flight call is "a harsh, nasal ''gzee gzee''".

Status

The IUCN has assessed the sickle-winged nightjar as being vulnerable. Its fairly small population is rapidly declining due to habitat loss and degradation.

References

{{Taxonbar, from=Q1259575

sickle-winged nightjar
Birds of Argentina
Birds of Brazil
Birds of Paraguay
sickle-winged nightjar
Taxonomy articles created by Polbot