Archived 2014 discussion: Horned Curassow (Pauxi unicornis) is being split: list P. koepckeae as Critically Endangered and P. unicornis as Endangered?

The initial deadline for comments on this topic is 28 April 2014, and therefore later than for most other topics currently under discussion.

This is part of a consultation on the Red List implications of extensive changes to BirdLife’s taxonomy for non-passerines

Lynx Edicions and BirdLife International will soon publish the HBW-BirdLife Illustrated Checklist of the Birds of the World, building off the Handbook of the Birds of the World series, and BirdLife’s annually updated taxonomic checklist.

The new Checklist will be based on the application of criteria for recognising species limits described by Tobias et al. (2010). Full details of the specific scores and the basis of these for each new taxonomic revision will be provided in the Checklist.

Following publication, an open and transparent mechanism will be established to allow people to comment on the taxonomic revisions or suggest new ones, and provide new information of relevance in order to inform regular updates. We are also actively seeking input via a discussion topic here regarding some potential taxonomic revisions that currently lack sufficient information.

The new Checklist will form the taxonomic basis of BirdLife’s assessments of the status of the world’s birds for the IUCN Red List. The taxonomic changes that will appear in volume 1 of the checklist (for non-passerines) will begin to be incorporated into the 2014 Red List update, with the remainder, and those for passerines (which will appear in volume 2 of the checklist), to be incorporated into subsequent Red List updates.

Preliminary Red List assessments have been carried out for the newly split or lumped taxa. We are now requesting comments and feedback on these preliminary assessments.

Horned Curassow Pauxi unicornis is being split into P. unicornis and P. koepckeae, following the application of criteria set out by Tobias et al. (2010).

Prior to the taxonomic change, P. unicornis (BirdLife species factsheet) was listed as Endangered under criteria A2bcd+3bcd+4bcd, on the basis that the species was suspected to be undergoing a population decline of 50-79% over 44 years (estimate of three generations), owing to habitat loss and hunting pressure. Although the factsheet gives the rate of decline as ≥ 30% over 44 years, based on a forest loss analysis, the impact of hunting pressure is thought to be driving a much more rapid decline. The pre-split species is regarded as poorly known and the total population was estimated to number 1,000-4,999 mature individuals, assumed to roughly equate to 1,500-7,500 individuals in total.

Hunting for food seems to be the most serious threat in both Bolivia and Peru, with substantial negative impacts suspected throughout the range of the pre-split species (Gastañaga 2006). In Bolivia, forests within its elevation range are being cleared for cultivation (Dinerstein et al. 1995, Fjeldså in litt. 1999, Maillard 2006). Road-building and associated development have a negative impact and inhibit dispersal (Herzog and Kessler 1998, Fjeldså in litt. 1999). In Peru, subsistence agriculture threatens its habitat (R. MacLeod in litt. 2000), as does the opening up of the foothills to colonisation and hunting. Mining, oil exploration and illegal logging are potential future threats in El Sira, as well as forest clearance by colonists.

P. koepckeae is known only from the Cerros del Sira in Huánuco, Peru, and went unrecorded since its description in 1969 until local knowledge surveys in 2003 and observations in 2005 confirmed its continued existence (Gastañaga 2006, Gastañaga et al. 2011). The total population is estimated to number fewer than 400 individuals (Gastañaga in litt. 2007), with evidence that its numbers are declining (Gastañaga and Hennessey 2005). The species occurs at densities of up to 20 individuals/km2, although this appears to be exceptional and at most sites only one or two individuals have been found (R. MacLeod in litt. 2007).

This species inhabits cloud forest in the Cerros del Sira, being recorded elevations of around 1,100-1,700 m (Gastañaga et al. 2011, Socolar et al. 2013), although in the dry season individuals have also occasionally been found at lower levels (down to 950 m) along the upper edge of adjacent montane forest.

It is suggested that this species qualifies as Critically Endangered under criterion C2a(ii), on the basis that it is likely to number fewer than 250 mature individuals, forming a single sub-population, which is in continuing decline owing to on-going hunting pressure, habitat loss and habitat degradation.

P. unicornis (as defined following the taxonomic change) is found in Bolivia, being known from the adjacent Amboró and Carrasco National Parks (Cox et al. 1997, Herzog and Kessler 1998, Mee 1999, R. MacLeod in litt. 2000), and more recently has been found in Isiboro-Secure Indigenous Territory and National Park (TIPNIS) and along the outer edge of the Cordillera Mosetenes, Cochabamba, Bolivia (R. MacLeod in litt. 2007). It was formerly found along the length of Carrasco’s northern boundary (R. MacLeod in litt. 2000), but recent surveys found it in very few locations here (R. MacLeod in litt. 2007). Extensive searches over several years have failed to locate the species in Madidi National Park, La Paz, Bolivia (R. MacLeod in litt. 2003, Hennessey 2004, A. Maccormack in litt. 2004), in the rio Tambopata area near the Peru/Bolivia border (R. MacLeod in litt. 2004, Gastañaga and Hennessey 2005) and in the Cordillera Cocapata and along the inner edge of Cordillera Mosetenes in Cochabamba (R. MacLeod in litt. 2003, 2007).

This species inhabits dense, humid, lower montane forest and adjacent lowland evergreen forest at 400-1,400 m (R. MacLeod in litt. 2000, Gastañaga 2006, Maillard 2006, Gastañaga et al. 2011). For much of the year it stays above 550 m, but descends in the dry season (Renjifo and Renjifo 1997).

A model of forest loss in the Amazon basin since 2002 (Soares-Filho et al. 2006), combined with the species’s approximate range and data on its ecology and life history (following the methods of Bird et al. 2011), suggests that the species will lose 20-30% of suitable habitat in the Amazonian portion of its range (as defined by the model, and which accounts for 98% of its global extent of suitable habitat) over 44 years (estimate of three generations).

By taking the pessimistic (business as usual) scenario of this model and factoring in additional declines owing to the species’s susceptibility to hunting, fragmentation and edge-effects (following Bird et al. 2011), it is projected that it will decline by 39.8% over 44 years from 2002.

This Amazonian forest loss analysis suggests that the species qualifies as Vulnerable under criterion A4; however, given the categorisation of the pre-split species as Endangered under the A criterion, the forest loss analysis may underestimate the rate of population decline in this species. In accordance with this, Gastañaga et al. (2011) suggest that the species qualifies at least as Endangered and cite the A criterion. The estimated Extent of Occurrence of 9,300 km2 suggests that this species does not qualify as Endangered under the B criterion, as also suggested by Gastañaga  et al. (2011). However, the species may qualify as Endangered under criterion C2 (see Gastañaga  et al. 2011), if its population is estimated to include fewer than 2,500 mature individuals, either with at least 95% of mature individuals in one sub-population, or with multiple sub-populations of no more than 250 mature individuals each. Gastañaga et al. (2011) also suggest that P. unicornis could qualify as Critically Endangered under criterion A2d (population reduction of ≥80% over the past 44 years) on the basis of an observed deterioration in the level of protection afforded by national parks and associated increases in logging, hunting and cultivation within park boundaries.

Comments are invited and further information would be welcomed.


Bird, J. P., Buchanan, G. M., Lees, A. C., Clay, R. P., Develey. P. F., Yépez, I. and Butchart, S. H. M. (2011) Integrating spatially explicit habitat projections into extinction risk assessments: a reassessment of Amazonian avifauna incorporating projected deforestation. Diversity and Distributions DOI: 10.1111/j.1472 4642.2011.00843.x.

Cox, G., Read, J. M., Clarke, R. O. S. and Easty, V. S. (1997) Studies of Horned Curassow Pauxi unicornis in Bolivia. Bird Conservation International 7: 199–211.

Dinerstein, E., Olson, D. M., Graham, D. J., Webster, A. L., Primm, S. A., Bookbinder, M. P. and Ledec, G. (1995) A conservation assesssment of the terrestrial ecoregions of Latin America and the Caribbean. Washington, D.C.: World Bank.

Gastañaga, M. (2006) Peruvian Horned Curassow (Pauxi unicornis koepckeae) rediscovered in the Sira Mountains, Peru. Bulletin of the Cracid Specialist Group 22: 15–18.

Gastañaga, M. and Hennessey, A. B. (2005) Uso de información local para reevaluar la población de Pauxi unicornis en Perú. Cotinga 23: 18–22.

Gastañaga Corvacho, M., MacLeod, R., Brooks, D. M. and Hennessey, B. (2011) Distinctive morphology, ecology, and first vocal descriptions of Sira Curassow (Pauxi [unicornis] koepckeae): evidence for species rank. Ornitología Neotropical 22: 267–279.

Hennessey, A. B. (2004) A bird survey of Torcillo-Sarayoj, the lower Yungas of Madidi National Park, Bolivia. Cotinga: 73–78.

Herzog, S. K. and Kessler, M. (1998) In search of the last Horned Curassows Pauxi unicornis in Bolivia. Cotinga 10: 46–50.

Maillard, O. Z. (2006) Reciente espécimen de la pava copete de piedra (Pauxi unicornis) para Bolivia. Kempffiana 2(1): 95–98.

Mee, A. (1999) Habitat association and notes on the Southern Helmeted Curassow (Pauxi unicornis) in Parque Nacional Carrasco, Bolivia. Bull. CSG 9: 15–19.

Renjifo, J. and Renjifo, J. T. (1997) Pauxi unicornis: Biologia y Ecologia. In: Strahl, S. D., Beaujon, S., Brooks, D. M., Begazo, A. J., Sedaghatkish, G. and Olmos, F. (eds.) The Cracidae: their biology and conservation. Pp. 89-92. Surrey, Canada: Hancock House.

Soares-Filho, B. S., Nepstad, D. C., Curran, L. M., Cerqueira, G. C., Garcia, R. A., Ramos, C. A., Voll, E., McDonald, A., Lefebvre, P. and Schlesinger, P. (2006) Modelling conservation in the Amazon basin. Nature 440: 520–523.

Socolar, S. J., Gonzalez, O. and Forero-Medina, G. (2013) Noteworthy Bird records from the northern Cerros del Sira, Peru. Cotinga 35: 24–36.

Tobias, J. A., Seddon, N., Spottiswoode, C. N., Pilgrim, J. D., Fishpool, L. D. C. and Collar, N. J. (2010) Quantitative criteria for species delimitation. Ibis 152: 724–746.

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5 Responses to Archived 2014 discussion: Horned Curassow (Pauxi unicornis) is being split: list P. koepckeae as Critically Endangered and P. unicornis as Endangered?

  1. Ross MacLeod & Melvin Gastanaga says:

    On the basis of the published information in Gastanaga et al 2011 and Socolar et al 2013 and previous papers that all indicate P. koepckeae is very rare, occurs only in a narrow attitudinal band and is highly susceptible to hunting, the status of Critically Endangered under criteria C2a(ii) as suggested above seems appropriate. The species being endemic to the Cerros del Sira and the isolated nature of this fairly short and narrow mountain range mean that there can only be one sub-population and the estimate we made (Gatsanaga in litt. 2007) of a potential population of up to 400 individuals (this estimate was all individuals not the mature breeding population) was based on assuming that the species might eventually be found throughout the Cerros del Sira at appropriate altitudes. Local knowledge surveys and field visits since then suggests this is unlikely so a population estimate well below 250 mature individuals seems appropriate. In 2008, we collected reliable reports of a hunter trying to sell P. koepckeae for to local restaurants as bush meet and the species had been rediscovered due to reports from local hunters so hunting is a considerable threat.

  2. Ross MacLeod says:

    Field surveys in Carrasco National Park between 1998 and 2004, carried out by the University of Glasgow and Armonia, suggest Pauix unicornis is extremely vulnerable to hunting. The highest population density ever found for the species was monitored over this period in the valley of the Rio Leche. It declined from at least 20 singing territorial males in 1999 to none in 2004 at the same time as hunting evidence was recorded penetrating into the valley. As the species is highly vocal and easily detectable during the breeding season it seems likely the entire population was extirpated in 5 years. Since the 1990’s the type of human encroachment that happened at Rio Leche has happened throughout the 3 national parks (Carrasco, Amboro & TIPNIS) that cover the range of Pauxi unicornis. In reality many former reported Pauxi locations (like Rio Ichilo, the Oilbird caves at Villa Tunari etc) have experienced much worse encroachment (RM pers. obs., pers. com. of S. Herzog, B. Hennessey, R. Soria Azua, & V. Garcia Soles). It therefore seems reasonable to suspect there has been a more than 80% population decline in Pauxi unicornis since the 1990s. Looking at the future, the habitat loss scenario used in the Amazonian forest loss analysis mentioned above suggests 20-30% reduction in habitat so at least that size of reduction in the population seems certain. However, although the species can’t live outside forest habitat it’s true vulnerability is to hunting and this forest loss scenario will bring the entire range of Pauxi unicornis within half a day’s walk of human settlement and therefore hunting pressure. As the 3 national parks that might protect the species face encroachment for the growing of coca (UNODC 2012 Coca Monitoring Survey) and clearance for other farming it seems unlikely they are in a position to reverse the projected forest loss scenario or eliminate the threat of hunting. Without effective protection in the national parks a projected population decline for Pauxi unicornis of ONLY 80% over the next 3 generations ( 44 years) would seem an impossibly optimistic scenario. Personally, based on everything I have observed about the species vulnerability to hunting I think effective extinction of Pauxi unicornis in 20 to 30 years is the most likely outcome unless massive conservation action can be achieved. I thus think Pauxi unicornis should be classified as Critically Endangered both because of previous suspected declines and future predicted declines.

  3. Rodrigo W. Soria-Auza says:

    I do agree with R. MaCleod’s appreciation on P. unicornis’s conservation status. Most sites where this species was recorded have experienced habitat destruction. I recently supervised a undergraduate research work to evaluate the degree of forest destruction in this area. The outcomes were alarming. There is no single site along the Andean foothills where forest clearing have not happened. National parks in this region of Bolivia do not effectively protect this species.
    Forest destruction gives only a subestimation of the impact that humans have on this species. Humans easily move one day walk deeper into the humid forests for hunting game birds and mammals, and this can not be evaluated through satellite images.

  4. Andy Symes says:

    Preliminary proposals

    Based on available information, our preliminary proposals for the 2014 Red List would be to treat:

    P. unicornis as Critically Endangered under criterion A2acd+3cd+4acd

    P. koepckeae as Critically Endangered under criterion C2aii.

    There is now a period for further comments until the final deadline of 14 May, after which recommended categorisations will be put forward to IUCN.

    The final Red List categories will be published on the BirdLife and IUCN websites in mid-2014, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  5. Andy Symes says:

    Recommended categorisations to be put forward to IUCN

    Following further review, there have been no changes to our preliminary proposals for the 2014 Red List status of these species.

    The final categorisations will be published in mid-2014, following further checking of information relevant to the assessments by BirdLife and IUCN.

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