Archived 2019 topic: Baudo Oropendola (Psarocolius cassini): revise global status?

BirdLife species factsheet for Baudo Oropendola

Baudo Oropendola (Psarocolius cassini) is endemic to the Colombian Chocó, where it occurs in the foothills and lowlands around the serranías de los Saltos and de Baudó. Until recently, the species was only known from a limited number of sites at the headwaters of río Acandí and north of Ensenada de Utría National Park (Fraga and Sharpe 2018). During an expedition to the Western Cordillera in 2010, 70-80 individuals in two groups were discovered at c.120 km from Ensenada de Utría National Park (Fraga and Sharpe 2018).

Baudo Oropendola is not well known. It is assumed that the species is very rare and local (Renjifo et al. 2014). It is forest-dependent and occurs in both primary and secondary forests between 100 and 365 m, preferably in primary forest with a naturally open canopy and along rivers (Strewe 1999, Fraga and Sharpe 2018). Feeding mainly on insects and fruits, it forages in small groups in the canopy layer (Strewe 1999).

The species is suspected to be in decline. The most pertinent threat is the destruction of forests. Particularly along rivers, forests are being cleared for agriculture, oil palm plantations, infrastructural development and commercial or small-scale logging. Importantly, the two recently discovered groups in the Western Cordillera are currently unprotected, while deforestation in the region is accelerating (Fraga and Sharpe 2018). Additionally, Baudo Oropendola is being trapped for food and for the cagebird trade.

Currently, Baudo Oropendola is listed as Endangered under Criterion B1ab(i,ii,iii,v), indicating a very small Extent of Occurrence (EOO) and declines in population size and habitat availability. Integrating the recently discovered population and following IUCN guidelines, the EOO for this species has been re-calculated using a Minimum Convex Polygon (IUCN 2001, 2012, Joppa et al. 2016), as EOO is a measure of the spatial spread of areas occupied by a species, not the actual area it occupies. After re-calculating the EOO for Baudo Oropendola, this species appears to warrant a change in Red List status. Therefore, we present here our reassessment against all criteria for the species.

Criterion A – Tracewski et al. (2016) measured the forest loss within this species’s range between 2000 and 2012 as c. 57 km2. This roughly equates to a rate of forest loss of 1% over three generations (13.8 years) for this species, with the assumption that habitat loss has continued at the same rate to the present day. Population changes may be proportional to forest cover change. Even though Baudo Oropendola seems to be strictly forest-dependent (Fraga and Sharpe 2018), it is highly unlikely that the rate of population decline based on habitat loss alone approaches the threshold for Vulnerable. Therefore, Baudo Oropendola may be listed as Least Concern under this criterion.

Criterion B – Using a Minimum Convex Polygon, the Extent of Occurrence (EOO) has been calculated as 31,700 km2. This value is far too large for retaining the species as threatened under Criterion B1. The area of forested habitat within the range is given as 6,474 km2 by Tracewski et al. (2016), while Renjifo et al. (2014) report 4,536 km2 of remaining habitat. The Area of Occupancy (AOO) for the species has been calculated at 2,460 km2 (Renjifo et al. 2014). This value takes into account the suitability of remaining habitat and is close to the threshold for Vulnerable under Criterion B2 (AOO < 2,000 km2). In order to warrant listing as threatened under this criterion, at least two further conditions must be met.

Even though the species’s range certainly shows some level of fragmentation, the species itself is not considered to be severely fragmented sensu IUCN (IUCN 2012). The number of locations* of occurrence are unknown: yet, considering the fragmentation of the range, it is possible that the species occurs in less than 10 locations*. Consequently, Baudo Oropendola might qualify for condition (a). Furthermore, EOO, AOO, habitat quality and population size are suspected to be declining, but not fluctuating, thus fulfilling condition (b), but not (c). Therefore, unless new information on the number of locations* becomes available, Baudo Oropendola may be precautionarily listed as Near Threatened, approaching the threshold for Vulnerable under Criterion B2ab(i,ii,iii,v).

Criterion C – The population of Baudo Oropendola is estimated at 1,000-2,499 individuals in total (BirdLife International 2018). This number is confirmed by Renjifo et al. (2014), who report less than 2,500 individuals. This estimate roughly equates to 600-1,700 mature individuals. The population is assumed to be declining (BirdLife International 2018). However, in order to qualify for listing as threatened under Criterion C, the population decline needs to be either observed, estimated, projected or inferred. In the case of Baudo Oropendola, the population is suspected to be in decline, which is a lower level of confidence. Therefore, unless further information on the population decline becomes available, Baudo Oropendola would not meet the required conditions for listing as threatened under this criterion. However, if the species is precautionarily considered to be made up of only one subpopulation then it could be listed as Near Threatened under Criterion C2a(ii).

Criterion D – The population size of this species is estimated at 600-1,700 mature individuals. Assuming that the true population size is closer to the lower band of the estimate, the species may be listed as Vulnerable under Criterion D1.

Criterion E – To the best of our knowledge no quantitative analysis of extinction risk has been conducted for this species. Therefore, it cannot be assessed against this criterion.

Therefore, it is proposed that Baudo Oropendola (Psaricolius cassini) be listed as Vulnerable under Criterion D1. We welcome any comments on this proposed listing.

Please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of its Red List status. Therefore, please make sure your comments are relevant to the discussion outlined in the topic.

*The term ‘location’ refers to a distinct area in which a single threatening event can rapidly affect all individuals of the taxon present, with the size of the location depending on the area covered by the threatening event. Where a taxon is affected by more than one threatening event, location should be defined by considering the most serious plausible threat (IUCN 2001, 2012).

An information booklet on the Red List Categories and Criteria can be downloaded here and the Red List Criteria Summary Sheet can be downloaded here. Detailed guidance on IUCN Red List terms and definitions and the application of the Red List Categories and Criteria can be downloaded here.

References

BirdLife International. 2018. Species factsheet: Psarocolius cassini. http://www.birdlife.org. (Accessed 05/12/2018)

Fraga, R.; Sharpe, C. J. 2018. Baudo Oropendola (Psarocolius cassini). 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, Spain. https://www.hbw.com/node/62244 (Accessed 05/12/2018).

IUCN. 2001. IUCN Red List Categories and Criteria: Version 3.1. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, U.K.

IUCN. 2012. IUCN Red List Categories and Criteria: Version 3.1. Second edition. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, U.K. www.iucnredlist.org/technical-documents/categories-and-criteria

Joppa, L. N.; Butchart, S. H. M.; Hoffmann, M.; Bachman, S. P.; Akçakaya, H. R.; Moat, J. F.; Böhm, M.; Holland, R. A.; Newton, A.; Polidoro, B.; Hughes, A. 2016. Impact of alternative metrics on estimates of extent of occurrence for extinction risk assessment. Conservation Biology 30: 362-370.

Renjifo, L. M.; Gómez, M. F.; Velásquez-Tibatá, J.; Amaya-Villarreal, A. M.; Kattan, G. H.; Amaya-Espinel, J. D.; Burbano-Girón, J. 2014. Libro rojo de aves de Colombia, Volumen I: bosques húmedos de los Andes y la costa Pacífica. Editorial Pontificia Universidad Javeriana & Instituto Alexander von Humboldt, Bogotá D.C., Colombia.

Strewe, R. 1999. Notes on the rediscovery of the Baudó Oropendula Psaracolius cassini in Chocó, Colombia. Cotinga 12: 40-46.

Tracewski, Ł.; Butchart, S. H. M.; Di Marco, M.; Ficetola, G. F.; Rondinini, C.; Symes, A.; Wheatley, H.; Beresford, A. E.; Buchanan, G. M. 2016. Toward quantification of the impact of 21st-century deforestation on the extinction risk of terrestrial vertebrates. Conservation Biology 30: 1070-1079.

This entry was posted in Americas, Archive, South America and tagged , . Bookmark the permalink.

2 Responses to Archived 2019 topic: Baudo Oropendola (Psarocolius cassini): revise global status?

  1. Rosendo Manuel Fraga says:

    The category “vulnerable” is reasonable for the Baudó Oropendola.

  2. Red List Team (BirdLife International) says:

    Preliminary proposal
    Based on available information, our preliminary proposal for the 2019 Red List would be to adopt the proposed classifications outlined in the initial forum discussion.
    There is now a period for further comments until the final deadline in mid-July, after which the recommended categorisations will be put forward to IUCN.
    Please note that we will then only post final recommended categorisations on forum discussions where these differ from those in the initial proposal.
    The final 2019 Red List categories will be published on the BirdLife and IUCN websites in December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

Comments are closed.