![](http://wikieva.org.ve/images/thumb/Grallaria_chtonia_imagen_01.jpg/633px-Grallaria_chtonia_imagen_01.jpg) |
Táchira Antpitta Grallaria chthonia (Mercedes Madriz) |
Last
week, a team of UK and US scientists published a
paper identifying the conservation priorities for the world's 9,993 bird species based on evolutionary distinctness
, a measure of
a species’ contribution to the
total evolutionary history of its clade[...], expected to capture
uniquely divergent genomes and functions (Jetz
et al. 2014). In parallel, the Zoological Society of London compiled a list of the
world's
100 most Evolutionarily Distinct and Globally Endangered (EDGE) bird
species. The findings were widely publicised by the media.
The ZSL's EDGE list includes one Venezuelan bird, Táchira Antpitta
Grallaria chthonia,
ranked
89th. This Venezuelan endemic is one of the very few of the
world's birds that remain unknown in life: there are no photographs, no
sound recordings and no living person has ever encountered one. The
species is only known from four specimens collected at a single
locality nearly 60 years ago. In short, it is an avian enigma. Its curious specific epithet derives from the Greek
khthonios, meaning "in the earth"
– and it might as well be.
The only evidence that the bird really exists are the four museum
specimens languishing in the drawers of the Colección Ornitológica
Phelps in Caracas and the Smithsonian Institution in Washington DC.
All of them were obtained from the same tiny spot: Hacienda La
Providencia (c.7°38'N 72°15'W; Paynter 1982), along the río
Chiquito in southwestern Táchira state, on the eastern slopes of the
Páramo de Tamá in the Andes of western Venezuela. The holotype (COP
61.055, on deposit at USNM, now NMNH) was taken at 1,800 m by the
Phelps
Collection's intrepid collector Ramón Urbano on 10 February 1955, together with a
paratype. Two further skins – both males like the previous type
specimens – were obtained at 2,100 m the following March and the
species was described later that year by Wetmore and Phelps (1956).
The female has never been encountered.
That is the last time that the bird was seen in life. A three-day
search specifically for the species in September 1990 was
unsuccessful, but there was no reason to fear for its future, since
the type locality still held pristine forest above 1600 m (Collar
et
al. 1992). By December 1996 however, coffee plantations in the
río Chiquito Valley had advanced up to 1600 m, and much forest at
1900–2200 m (including the type locality) had been converted to
agriculture; although the species was not found at this time, it may
have been present in neighbouring valleys, which were apparently less
disturbed (BirdLife International 2000).
The type locality for
Grallaria chthonia and the forests that
surround it lie within Venezuela's El Tamá National Park, an IUCN
Category II protected area which extends over 1,390 km² and is
designated as an
Important
Bird Area (Lentino & Esclasans 2005), part of the
Colombian
East Andes Endemic Bird Area. In addition, the known and
potential range falls within
one
of the highest priority bioregions for the conservation of
Venezuela's birds (Rodríguez
et al. 2004). This region is
also recognised as one of the most threatened in Venezuela, with at
least 17% of the habitat within the National Park affected by
deforestation for agriculture (principally coffee cultivation) and to
create livestock pasture (Sharpe & Lentino 2008).
For the above reasons, Táchira Antpitta is considered Critically
Endangered both
nationally
and
internationally
(Sharpe 2008, BirdLife International 2014). Its population is now
estimated to consist of fewer than 50 mature individuals (BirdLife
International 2014).
Basic field surveys are urgently needed in order to determine the
true status of this virtually unknown antpitta; seasonality of
vocalisation should be taken into account, with surveys to be carried
out in May–June (BirdLife International 2014). In addition, there
are questions over its true taxonomic status. On plumage characters,
Grallaria chthonia appears to be most closely related to
G.
guatimalensis and Hilty (2003) suggests that it may be a higher
elevation subspecies of the latter. On the other hand, Ridgely & Tudor (1994) and
Krabbe & Schulenberg (2003) believe that
chthonia
is probably more more similar to (or even conspecific with)
alleni. Until
the species is better known, with molecular and vocal evidence
considered, the true affinities of this
evolutionarily
distinct and globally endangered species will remain uncertain.
Further information on this species – and all the world's birds – can be found at
HBW Alive.
References
BirdLife International (2000)
Threatened birds of the world. Lynx Edicions & BirdLife
International: Barcelona & Cambridge. 852 pp.
Collar, N.J., Gonzaga, L.P., Krabbe,
N., Madroño, A., Naranjo, L.G., Parker, T.A. & Wege, D.C. (1992)
Threatened birds of the Americas. The ICBP/IUCN Red Data Book.
3rd edition, part 2. ICBP: Cambridge. 1,150 pp.
Hilty, S. L. (2003) Birds of
Venezuela. Princeton University Press: Princeton NJ. 928 pp.
Jetz, W., Thomas, G.H., Joy, J.B.,
Redding, D.W., Hartmann, K., Mooers, A.O. (2014)
Global distribution and conservation of evolutionary distinctness in birds.
Current
Biology.
Krabbe, N.K. & Schulenberg, T.S.
(2003) Family Formicariidae (ground-antbirds). Pp. 682-731 in del
Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana,
E. (eds.) Handbook of the birds of the world. Volume 8. Lynx
Edicions: Barcelona. 845 pp.
Krabbe, N.K., Schulenberg, T.S. &
Sharpe, C.J. (2013)
Tachira Antpitta (Grallaria chthonia).
In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de
Juana, E. (eds.) Handbook of the birds of the world alive. Lynx
Edicions: Barcelona. Retrieved from http://www.hbw.com/node/56887 on
17 April 2014.
Lentino, M. & Esclasans, D. (2005)
Áreas importantes para la conservación de las aves en Venezuela. Pp.
621-769 in: BirdLife International and Conservation International
(eds.)
Áreas importantes para la conservación de las aves en los
Andes Tropicales (Serie de Conservación de BirdLife, No. 14).
BirdLife International: Quito, Ecuador.
Paynter, R.A. (1982) Ornithological
gazetteer of Venezuela. Harvard University, Museum
of Comparative Zoology: Cambridge, Mass. 245 pp.
Ridgely, R.S. & Tudor, G. (1994) The birds of South America. Volume II: the suboscine passerines. University of Texas Press: Austin. 814pp.
Sharpe, C.J. (2008)
Aves. Pp.
116-157
in: Rodríguez, J.P. & Rojas-Suárez, F. eds.
Libro Rojo de la
fauna venezolana, 3rd edition. Provita
& Shell Venezuela, S.A., Caracas, Venezuela. 364 pp.
Sharpe, C.J. & Lentino, M. (2008)
Hormiguero tororoi tachirense
Grallaria chthonia. P. 144 in:
Rodríguez, J.P. & Rojas-Suárez, F. eds.
Libro Rojo de la
fauna venezolana, 3rd edition. Provita
& Shell Venezuela, S.A., Caracas, Venezuela. Available online as: Sharpe, C.J. & Lentino, M. (2013)
Hormiguero tororoi tachirense Grallaria chthonia. WikiEVA: Especies Venezolanas Amenazadas.
Wetmore, A. & Phelps, W.H. (1956)
Further additions to the list of birds of Venezuela. Proceedings
of the Biological Society of Washington 69: 1-10.
Recommended citation:-
Sharpe, C.J. (2014)
Táchira Antpitta Grallaria chthonia
on the EDGE: evolutionarily distinct and globally endangered. The Curious Naturalist. Downloaded from http://thecuriousnaturalist.blogspot.com/2014/04/tachira-antpitta-grallaria-chthonia-on.html on
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