Thebearded tachuri(Polystictus pectoralis) is aNear Threatenedspecies ofbirdin subfamily Elaeniinae of familyTyrannidae,the tyrant flycatchers. It is found in every mainland South American country except Chile, Ecuador, and Peru.[1][2]
| Bearded tachuri | |
|---|---|
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| Female atBonito,Mato Grosso do Sul,Brazil | |
Scientific classification
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Family: | Tyrannidae |
| Genus: | Polystictus |
| Species: | P. pectoralis
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| Binomial name | |
| Polystictus pectoralis (Vieillot,1817)
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Taxonomy and systematics
editThe bearded tachuri shares genusPolystictuswith thegrey-backed tachuri(P. superciliaris) but several authors have described the relationship as weak and needing confirmation.[3][4]
As of late 2024, the bearded tachuri is assigned these three subspecies:
- P. p. bogotensis(Chapman,1915)
- P. p. brevipennis(Berlepsch&Hartert, EJO,1902)
- P. p. pectoralis(Vieillot,1817)
The two subspecies other than thenominateP. p. pectoralishave been suggested as individual species.[3]P. p. bogotensisis believed extinct.[1]
Description
editThe bearded tachuri is 8 to 10.5 cm (3.1 to 4.1 in) long and weighs 6 to 8 grams (0.21 to 0.28 oz). Adult males of the nominate subspecies have a dusky gray to blackish crown with a bushy but usually flattened crest; the crown's white center is mostly hidden. They have a short whitesuperciliumand a thin blackish line through the eye on a face that is otherwise thinly striped with black and white. Their upperparts are mostly buffy brown with a tawny to rufous rump. Their wings are dusky with bright cinnamon-buff edges on the flight feathers and tips on the wingcoverts;the last show as twowing bars.Their tail is dusky. Their chin ( "beard" ) has thin black and white stripes. Their throat and underparts are pale yellowish white with a cinnamon wash on the breast and flanks. Adult females are duller overall than males. They do not have the male's "beard". Their crown and face are mostly brown and their throat is whitish. Juveniles have reddish edges on their flight feathers, buffy wing bars, and deeper yellow underparts than adults. SubspeciesP. p. brevipennisis significantly smaller than the nominate; its crest is smaller and males have less black on their face and throat.P. p. bogotensisis quite different from the other two subspecies. Compared to them its crest is thinner and longer, its crown has less white, its supercilium is bright buff, its face ochraceous tawny, its back more tawny, the edges of its flight feathers and wing coverts deeper tawny, its throat nearly all white, and its flanks a deeper and richer tawny. Both sexes of all subspecies have a fuscous brown iris, a black bill, and black legs and feet.[4][5][6][7][8][excessive citations]
Distribution and habitat
editThe bearded tachuri has a highlydisjunct distribution.The nominate subspecies has the largest range. It is found in eastern Bolivia, much of Paraguay, western Uruguay, northern Argentina south toMendoza,La PampaandBuenos Airesprovinces, and southern Brazil in an area roughly bounded byMato Grosso,southernMinas Gerais,andMato Grosso do Sul.SubspeciesP. p. brevipennisis found from eastern Colombia into western Venezuela, in several area in central and southeastern Venezuela, and separately in each ofthe Guianasand portions of northern Brazil.P. p. bogotensisis (or was) found very locally in Colombia'sCundinamarcaandValle del Caucadepartments. The bearded tachuri is primarily a grassland species. It occurs in savanna with scattered shrubs and scrub, tall grassy areas incerrado,Venezuela'sGran Sabana,andcampos rupestresin Brazil. In elevation it mostly occurs below 1,300 m (4,300 ft) butP. p. bogotensisreaches 2,600 m (8,500 ft).[4][5][6][7][8][excessive citations]
Behavior
editMovement
editThe bearded tachuri is mostly resident. However, the southernmost population may move north for theaustralwinter, as the species is known in Bolivia and adjacent Brazil only in that season. In other areas it may wander to find suitable habitat.[1][4][6]
Feeding
editThe bearded tachuri feeds mostly on insects. It usually forages singly, sometimes in pairs, and occasionally joinsmixed-species feeding flocks.It perches high in grass or a shrub, gleaning from the perch and making short flights just above the vegetation to hover-glean or move to another perch.[4][6]
Breeding
editThe bearded tachuri's breeding season varies geographically. It includes June and July in eastern Colombia and from September to January in Argentina and most of Brazil. The species is thought to bepolygynous.Males make a flight display with song and wing-buzzing. Its nest is an open cup made from grass and other plant fibers, thistle down, and spider web. It is typically place in a shrub within about 1 m (3 ft) of the ground. The clutch size is three eggs. The incubation period, time to fledging, and details of parental care are not known.[4][6]
Vocalization
editThe bearded tachuri sings both from a perch and during its flight display, a "very high, thin series of about 3 'see sisi' notes, ending in an odd, low, toneless, very short 'krrak', together as 'see sisi-krrak'".[7]It also makes "weak rising 'feee' or 'pewee'" contact calls.[4]
Status
editTheIUCNhas originally in 1988 assessed the bearded tachuri as Threatened and since 2004 as Near Threatened. Its population size is not known and is believed to be decreasing. SubspeciesP. p. bogotensishas no confirmed records since the 1950s and is probably extinct. The other subspecies are "generally scarce and localized...Conversion to agriculture forEucalyptusplantations, arable agriculture (largely soybeans, maize and rice) and pastures have had a severe impact on its habitat in Brazil...The species's strict habitat requirements render it vulnerable to habitat degradation throughovergrazingand fire. Conversion of land to oil palm plantations could pose a future threat. "[1]It occurs in at least one protected area in most of the countries it inhabits.[4]
References
edit- ^abcdeBirdLife International (2021)."Bearded TachuriPolystictus pectoralis".IUCN Red List of Threatened Species.2021:e.T22699420A181985168.doi:10.2305/IUCN.UK.2021-3.RLTS.T22699420A181985168.en.Retrieved20 October2024.
- ^Gill, Frank;Donsker, David;Rasmussen, Pamela,eds. (August 2024)."Tyrant flycatchers".IOC World Bird List.v 14.2.Retrieved19 August2024.
- ^abRemsen, 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 28 September 2024. A classification of the bird species of South America. American Ornithological Society.https://www.museum.lsu.edu/~Remsen/SACCBaseline.htmretrieved September 29, 2024
- ^abcdefghFitzpatrick, J. W. and C. J. Sharpe (2020). Bearded Tachuri (Polystictus pectoralis), 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.beatac1.01retrieved October 20, 2024
- ^abMcMullan, Miles; Donegan, Thomas M.; Quevedo, Alonso (2010).Field Guide to the Birds of Colombia.Bogotá: Fundación ProAves. p. 151.ISBN978-0-9827615-0-2.
- ^abcdeHilty, Steven L. (2003).Birds of Venezuela(second ed.). Princeton NJ: Princeton University Press. p. 580.
- ^abcvan Perlo, Ber (2009).A Field Guide to the Birds of Brazil.New York: Oxford University Press. pp. 294–295.ISBN978-0-19-530155-7.
- ^abde la Peña, Martín R.; Rumboll, Maurice (2001).Birds of Southern South America and Antarctica.Princeton Illustrated Checklists. New Jersey: Princeton University Press. pp. Plate 72, map 72.2.ISBN0691090351.