The chestnut-shouldered antwren (''Euchrepomis humeralis'') is a species of

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

in subfamily Euchrepomidinae of family

Thamnophilidae The antbirds are a large passerine bird family, Thamnophilidae, found across subtropical and tropical Central and South America, from Mexico to Argentina. There are more than 230 species, known variously as antshrikes, antwrens, antvireos, fire ...

, the "typical antbirds". It is found in

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

Ecuador Ecuador, officially the Republic of Ecuador, is a country in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean on the west. It also includes the Galápagos Province which contain ...

, and

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

Taxonomy and systematics

The chestnut-shouldered antwren was described by the English ornithologists

Philip Sclater Philip Lutley Sclater (4 November 1829 – 27 June 1913) was an England, English lawyer and zoologist. In zoology, he was an expert ornithologist, and identified the main zoogeographic regions of the world. He was Secretary of the Zoological ...

and

Osbert Salvin Osbert Salvin (25 February 1835 – 1 June 1898) was an English natural history, naturalist, Ornithology, ornithologist, and Herpetology, herpetologist best known for co-authoring ''Biologia Centrali-Americana'' (1879–1915) with Frederick DuC ...

in 1880 and given the

binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...

''Terenura humeralis''. There it remained until the current genus ''

Euchrepomis ''Euchrepomis'' is a genus of insectivorous passerine birds in the antbird, antbird family, Thamnophilidae. In 2012 Gustavo Bravo and colleagues introduced the genus ''Euchrepomis'' for four species that were previously placed in the genus ''Ter ...

'' was created in 2012 following

phylogenetic analysis In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...

. The chestnut-shouldered antwren is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

Description

The chestnut-shouldered antwren is long and weighs about . The sexes have different plumage. Adult males have a whitish

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 k ...

and a thin dark line through the eye on an otherwise pale gray face. Their crown and nape are black, their back greenish olive, their rump rufous-chestnut, and their uppertail

coverts A covert feather or tectrix on a bird is one of a set of feathers, called coverts (or ''tectrices''), which cover other feathers. The coverts help to smooth airflow over the wings and tail. Ear coverts The ear coverts are small feathers behind t ...

and tail grayish olive. Their wing coverts are blackish gray with whitish tips that form two bars on the closed wing, their flight feathers olive-tinged blackish gray with pale olive-yellow edges, and the bend of the wing rufous-chestnut. Their throat and breast are pale gray and their belly and undertail coverts are pale yellow. Adult females have an olive-brown crown, nape and eyeline, a pale gray supercilium, and dark olive-brown wings with at most a trace of chestnut at the bend.Zimmer, K. and M.L. Isler (2020). Chestnut-shouldered Antwren (''Euchrepomis humeralis''), 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.chsant1.01 retrieved December 26, 2023

Distribution and habitat

The chestnut-shouldered antwren is found from eastern Ecuador and eastern Peru south of the Rio Napo south into northwestern Bolivia and east in Brazil through northern

Rondônia Rondônia () is one of the 26 states of Brazil, located in the northern subdivision of the country (central-western part). It is bordered by Acre (state), Acre in the west, Amazonas, Brazil, Amazonas in the north, Mato Grosso in the east, and Bo ...

and into Amazonas state as far as the Rio Madeira. It inhabits the subcanopy and canopy of '' terra firme'' and drier floodplain tropical evergreen forest.

Behavior

Movement

The chestnut-shouldered antwren is believed to be a year-round resident throughout its range.

Feeding

The chestnut-shouldered antwren feeds on

arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

s, though details of its diet are lacking. It typically forages in pairs or small family groups that usually join

mixed-species feeding flock A mixed-species feeding flock, also termed a mixed-species foraging flock, mixed hunting party or informally bird wave, is a flock of usually insectivorous birds of different species that join each other and move together while foraging. These ar ...

s. It forages almost entirely in the forest canopy, acrobatically gleaning prey from leaves and the ends of branches.

Breeding

Nothing is known about the chestnut-shouldered antwren's breeding biology.

Vocalization

The chestnut-shouldered antwren's song is "very high, thin, slightly descending, gradually accelerating to a 'fuh-fuh-weet-weet-d-rrr' rattle".

Status

The

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

has assessed the chestnut-shouldered antwren as being of Least Concern. It has a very large range but its population size is not known and is believed to be decreasing. No immediate threats have been identified. It is considered fairly common in most of its range and occurs in several protected areas.

References

{{Taxonbar, from=Q27075125 chestnut-shouldered antwren Birds of the Amazon rainforest Birds of the Ecuadorian Amazon Birds of Peruvian Amazonia chestnut-shouldered antwren chestnut-shouldered antwren chestnut-shouldered antwren Taxonomy articles created by Polbot