The Delta Amacuro softtail (''Thripophaga amacurensis'') is a

Vulnerable species A vulnerable species is a species which has been Conservation status, categorized by the International Union for Conservation of Nature as being threatened species, threatened with extinction unless the circumstances that are threatened species, ...

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 Furnariinae subfamily of the ovenbird

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Furnariidae. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the southern

Orinoco Delta The Orinoco Delta is a vast river delta of the Orinoco River, located in eastern Venezuela. Location The Orinoco Delta is one of the eight natural regions of Venezuela. It covers the whole of Delta Amacuro State and a few square kilometers of M ...

in northeastern

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

.Clements, J. F., P.C. Rasmussen, T. S. Schulenberg, M. J. Iliff, T. A. Fredericks, J. A. Gerbracht, D. Lepage, A. Spencer, S. M. Billerman, B. L. Sullivan, and C. L. Wood. 2023. The eBird/Clements checklist of birds of the world: v2023. Downloaded from https://www.birds.cornell.edu/clementschecklist/download/ retrieved October 28, 2023

Taxonomy and systematics

The Delta Amacuro softtail was described in 2013 and named for the Venezuelan state of

Delta Amacuro Delta Amacuro State ( es, Estado Delta Amacuro, ) is one of the 23 states of Venezuela, and is the location of the Orinoco Delta. The Paria Gulf and the Atlantic Ocean are found to the north, Bolívar State is found to the south, the Atlantic O ...

in which it occurs. The species had first been collected in 1899, and observed and again collected in the twentieth century, but was not recognized as a distinct species until a series of expeditions beginning in 2004. The Delta Amacuro softtail 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 "unispec ...

Description

The Delta Amacuro softtail is about long and weighs . The sexes have almost the same plumage. Adult males have olive-buff lores with dark gray tips and a grayish olive eyering; the rest of their head is brownish olive with yellow-buff spots. Their upper back is brownish olive with yellow-buff streaks. Their rest of their back is plain warm brown and their rump and uppertail

coverts A covert feather or tectrix on a bird is one of a set of feathers, called coverts (or ''tectrices''), which, as the name implies, cover other feathers. The coverts help to smooth airflow over the wings and tail. Ear coverts The ear coverts are sm ...

rufous-brown or cinnamon. Their tail is cinnamon that is brighter on its upper side. Their upperwing coverts are warm olive-brown to fulvous-brown. Their

primaries Primary elections, or direct primary are a voting process by which voters can indicate their preference for their party's candidate, or a candidate in general, in an upcoming general election, local election, or by-election. Depending on the c ...

and secondaries are dusky with warmer brown edges on the outer webs and their tertials are rufescent brown. Their chin is cinnamon-buff, their throat rufous chestnut, and their breast and belly brownish olive with buffy teardrops that become less well defined on the latter. Their flanks and thighs are plain brownish olive and their undertail coverts tinged warm ochraceous tawny. Their iris is rusty brown, their bill steel gray with dusky at the

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

's base and pale pink at the

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

's, and their legs and feet dull yellowish green. Females differ only in having a paler chin and throat than males.Fjeldså, J. and C. J. Sharpe (2020). Delta Amacuro Softtail (''Thripophaga amacurensis''), 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.deasof1.01 retrieved November 11, 2023

Distribution and habitat

The Delta Amacuro softtail is found in the southern part of the Orinoco River Delta in the northern Venezuelan state of Delta Amacuro. It is known from only four sites along the Brazo Imataca, a subsidiary channel of the Orinoco. It inhabits mature floodplain forest along streams and rivers. Some small marshes and seasonally flooded savanna are interspersed. The area floods between May and October.

Behavior

Movement

The Delta Amacuro softtail's movements, if any, are not known.

Feeding

The Delta Amacuro softtail's diet is not known. It forages alone or in pairs, poking into trapped debris, vine tangles, and other foliage, usually between about above the ground.

Breeding

Nothing is known about the Delta Amacuro softtail's breeding biology.

Vocalization

The Delta Amacuro softtail's song is often sung in duet. It is "a long chattery rattle consisting of short, loud notes given by one bird (perhaps male), then joined for variable period of time by a second bird making harsh, even shorter notes; after this, volume and tempo gradually decrease until song typically ends with only the first bird singing".

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 ...

originally assessed the Delta Amacuro softtail as Endangered but since 2021 has rated it Vulnerable. It has a very small range and an unknown population size that is believed to be decreasing. "In the eastern part of its range there appear to be no immediate threats, but in the west deforestation may be affecting this species. Logging, oil exploration and clearance for agriculture are particular threats; and by April 2010 the most westerly of its four sites had been deforested." "The known range is entirely unprotected, falling outside existing protected areas. Surveys reneeded to define the precise range and population size."

References

{{Taxonbar, from=Q14915971

Delta Amacuro softtail The Delta Amacuro softtail (''Thripophaga amacurensis'') is a Vulnerable species of bird in the Furnariinae subfamily of the ovenbird family Furnariidae. It is endemic to the southern Orinoco Delta in northeastern Venezuela.Clements, J. F., P ...

Endemic birds of Venezuela