Rio de Janeiro antwren

Type of bird

Not to be confused with Rio de Janeiro antbird.

Rio de Janeiro antwren

Scientific classification
Domain:  | Eukaryota
Kingdom:  | Animalia
Phylum:  | Chordata
Class:  | Aves
Order:  | Passeriformes
Family:  | Thamnophilidae
Genus:  | Myrmotherula
Species:  |

M. fluminensis

Binomial name
Myrmotherula fluminensis

Gonzaga, 1988

Synonyms

Myrmotherula luctuosa

The Rio de Janeiro antwren (Myrmotherula fluminensis) is a bird in subfamily Thamnophilinae of family Thamnophilidae, the "typical antbirds". It is endemic to Brazil.[1]

## Taxonomy and systematics

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The Rio de Janeiro antwren is known only from the holotype and a few observations, and its taxonomy is unsettled.[2] The bird's discoverer, the South American Classification Committee of the American Ornithological Society, the International Ornithological Committee, and the Clements taxonomy consider it a full species.[3][4][1][5] BirdLife International's Handbook of the Birds of the World (HBW) does not recognize it as a taxon but as a color morph of the silvery-flanked antwren (M. luctuosa).[6] Other authors have suggested that it could a hybrid between the silvery-flanked antwren and the unicolored antwren (M. unicolor).[2][6] Gonzaga, who discovered the bird, noted that treating it as a color morph or a hybrid are plausible alternatives to full species status.[4]

## Description

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The Rio de Janeiro antwren is about 10 cm (3.9 in) long. The type specimen weighed 9 g (0.32 oz). The adult male has a whitish ring around the eye and stripe below it. It has gray upperparts. Its wings are darker gray with white-tipped black coverts. Its tail is gray. Its throat, breast, and center of its belly are black. The rest of its underparts are the same gray as the upperparts. It has a brown iris, a blackish brown bill, and pale bluish gray feet with yellowish soles. The female has not been described.[4][2][7]

## Distribution and habitat

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The holotype of the Rio de Janeiro antwren was collected in 1988 in Brazil's central Rio de Janeiro state.[4] It has not been seen again at that site, and was not seen again anywhere until 1994. Then and since it has been recorded a few times in Reserva Ecológica Guapiaçu (REGUA), which is near the type locality. The holotype was collected in a highly disturbed small woodlot near sea level. The sightings at REGUA have been in secondary forest that is less than 25 years old; the sightings were near old clearings and at elevations between 35 and 200 m (100 and 700 ft).[2]

## Behavior

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### Movement

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The Rio de Janeiro antwren's movement pattern, if any, is not known. The holotype was collected at a site that had been studied for seven years, which prompted speculation by the original author and others that the bird could be a straggler or altitudinal migrant from the nearby Serra dos Órgãos.[2][4]

### Feeding

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The Rio de Janeiro antwren's diet is almost unknown. The holotype's stomach contained the remains of arthropods. The species has been observed feeding with mixed-species foraging flocks, usually within about 2 m (7 ft) of the ground.[2][4]

### Breeding

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Nothing is known about the Rio de Janeiro antwren's breeding biology.[2]

### Vocalization

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As of early 2024 neither xeno-canto nor the Cornell Lab of Ornithology's Macaulay Library have recordings of Rio de Janeiro antwren vocalizations. Apparently some have been made, because authors note that the vocalizations are almost or entirely indistinguishable from those of the silvery-flanked antwren.[2][8]

## Status

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The IUCN follows HBW taxonomy and so has not assessed the Rio de Janeiro antwren separately from the silvery-flanked antwren.[9]

## References

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1. ^ a b Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (January 2024). "Antbirds". IOC World Bird List. v 14.1. Retrieved January 4, 2024.
2. ^ a b c d e f g h Zimmer, K., M.L. Isler, and C. J. Sharpe (2020). Rio de Janeiro Antwren (Myrmotherula fluminensis), 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.rdjant2.01 retrieved February 13, 2024
3. ^ Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, G. Del-Rio, A. Jaramillo, D. F. Lane, M. B. Robbins, F. G. Stiles, and K. J. Zimmer. Version 26 November 2023. A classification of the bird species of South America. American Ornithological Society. https://www.museum.lsu.edu/~Remsen/SACCBaseline.htm retrieved November 27, 2023
4. ^ a b c d e f Gonzaga, L.P. (1988). A new antwren (Myrmotherula) from southeastern Brazil. Bull. Brit. Orn. Club. 108(3): 132-135
5. ^ 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
6. ^ a b HBW and BirdLife International (2023). Handbook of the Birds of the World and BirdLife International digital checklist of the birds of the world. Version 8. Available at: http://datazone.birdlife.org/userfiles/file/Species/Taxonomy/HBW-BirdLife_Checklist_v8_Dec23.zip retrieved December 28, 2023
7. ^ van Perlo, Ber (2009). A Field Guide to the Birds of Brazil. New York: Oxford University Press. pp. 242–243. ISBN 978-0-19-530155-7.
8. ^ Pimentel, L., and F. Olmos (2011). The birds of Reserva Ecológica Guapiaçu (REGUA), Rio de Janeiro, Brazil. Cotinga 33:6–22. http://www.neotropicalbirdclub.org/articles/33/Pimentel.pdf
9. ^ BirdLife International (2017). "Silvery-flanked Antwren Myrmotherula luctuosa". IUCN Red List of Threatened Species. 2017: e.T103657471A112309679. doi:10.2305/IUCN.UK.2017-1.RLTS.T103657471A112309679.en. Retrieved 13 February 2024.

## External links

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* Data related to Myrmotherula fluminensis at Wikispecies

Taxon identifiers

Myrmotherula fluminensis|

* Wikidata: Q120264
* Wikispecies: Myrmotherula fluminensis
* Avibase: AD84BFB22781E89E
* BirdLife: 22701502
* BOW: rdjant2
* CoL: 45CZ7
* eBird: rdjant2
* GBIF: 2490193
* iNaturalist: 15834
* IRMNG: 11259519
* ITIS: 561408
* NCBI: 2765397
* Neotropical: rdjant2
* Observation.org: 74341
* Open Tree of Life: 4947793
* Xeno-canto: Myrmotherula-fluminensis