The olive-crowned crescentchest (''Melanopareia maximiliani'') is a species of

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

in the family Melanopareiidae. It is found in

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

, and

Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...

Taxonomy and systematics

The crescentchests (genus ''Melanopareia'') were previously included in family Rhinocryptidae, the tapaculos. A 2010 publication confirmed earlier work and created their present genus.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 19 January 2021. A classification of the bird species of South America. American Ornithological Society. https://www.museum.lsu.edu/~Remsen/SACCBaseline.htm retrieved January 19, 2021 The olive-crowned crescentchest has three subspecies, the nominate ''Melanopareia maximiliani maximiliani'', ''M. m. argentina'', and ''M. m. pallida''. The last has been suggested as a separate species due to vocal differences. In addition, a subpopulation of ''M. m. pallida'' might be an undescribed taxon.Boesman, P. (2016). Notes on the vocalizations of Olive-crowned Crescentchest (''Melanopareia maximiliani''). HBW Alive Ornithological Note 67. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona.

Description

The olive-crowned crescentchest is long. Males weigh , one female weighed , and unsexed specimens weighed . The nominate subspecies' crown and upperparts are olive-brown, the throat deep buff, and the chest and belly ochraceous. It has a narrow buff

supercilium The supercilium is a plumage feature found on the heads of some bird species. It is a stripe which runs from the base of the bird's beak above its eye, finishing somewhere towards the rear of the bird's head.Dunn and Alderfer (2006), p. 10 Also ...

with a black mask below and a black crescent and chesnut band between the throat and chest. ''M. m. argentina'' is similar but has paler underparts. ''M. m. pallida'' is paler still, its throat is more cinnamon than buff, and the facial mask is a lighter black.Krabbe, N. and T. S. Schulenberg (2020). Olive-crowned Crescentchest (''Melanopareia maximiliani''), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.olccre1.01 retrieved May 3, 2021

Distribution and habitat

The nominate subspecies of olive-crowned crescentchest is found in La Paz Department of western Bolivia. ''M. m. argentina'' is found from central Bolivia to northwestern Argentina. ''M. m. pallida'' is found in southeastern Bolivia, western Paraguay, and northern Argentina. The species generally inhabits dry scrub and grassy areas with small bushes, but ''M. m. pallida'' also frequents sawgrass in the

Chaco Basin The Chaco Basin ( es, Cuenca Chaco, es, Cuenca Chaco Paranaense or es, Cuenca Chaco-Paraná) is a major sedimentary basin in Central South America around the borders of Argentina, Bolivia and Paraguay. The basin forms part of the larger Paraná ...

. It ranges in elevation mostly from but is found as low as in Argentina.

Behavior

Feeding

The olive-crowned crescentchest usually forages alone, but sometimes in pairs, by hopping through dense cover on or near the ground. Its diet has not been recorded.

Breeding

In Argentina the olive-crowned crescentchest breeds from September to December; an active nest was found in October in central Bolivia. Two nests of ''M. m. pallida'' were cups of vegetable fiber and palm leaves; they were hidden not far above the ground. One nest of ''M. m. argentina'' was a tunnel lined with grass. The species' clutch is two or three eggs.

Vocalization

The nominate olive-crowned crescentchest and ''M. m. argentina'' have two songs, one described as "chuck" note

and the other as "chi" note

The song of ''M. m. pallida'' is faste

The species' call is described as "chit chuck

Status

The

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

has assessed the olive-crowned crescentchest as being of Least Concern. It is locally fairly common and in Argentina occurs in several protected areas.

References

{{Taxonbar, from=Q1264720 olive-crowned crescentchest Birds of the Gran Chaco Birds of Paraguay Birds of the Yungas olive-crowned crescentchest Taxonomy articles created by Polbot