BirdLife species factsheet for Yellow-shouldered Amazon
This discussion was first published as part of the 2019 Red List update. At the time a decision regarding the status of this species was pended, but to enable potential reassessment of this species as part of the 2021 Red List update this post remains open and the date of posting has been updated.
Yellow-shouldered Amazon is found in two isolated populations in northern coastal Venezuela (one in the north-west near Coro and one in the north-east near Puerto la Cruz), as well as on the islands of Margarita, La Blanquilla, Curaçao and Bonaire (Rodríguez-Ferraro 2009). It is extinct in the Paraguaná peninsula on mainland Venezuela (Briceño-Linares et al. 2011) and on Aruba. The species inhabits xerophytic vegetation, frequenting desert shrublands dominated by cacti and low thorn-bushes or trees, but may require tracts of denser woodland (Collar et al. 2018).
Yellow-shouldered Amazon is suspected to have undergone a population decline in the past owing to illegal poaching and habitat loss. The main threat stems from the pet trade (C. J. Sharpe in litt. 2011, Rojas-Suárez and Rodríguez 2015). Yellow-shouldered Amazons are heavily exploited for trade, serving a strong internal pet market. Additionally, it is prosecuted as a crop pest (Collar et al. 2018). The species’s habitat is converted for infrastructural and industrial developments, tourism, farmland and mining. These threats are further compounded by occasional droughts, particularly on the islands (Collar et al. 2018).
The population is estimated to number between 2,590 and 8,470 individuals, roughly equating to 1,700-5,600 mature individuals. The species’s current population trend is not clear though. The largest subpopulation on Margarita Island has increased from 750 birds (c. 500 mature individuals) in 1989 (Sanz and Grajal 1998) to over 1,600 (c. 1000 mature individuals) in 2008 (Briceño-Linares et al. 2011) and is currently considered to be stable (V. Sanz in litt. 2016). On Bonaire, the population size increased moderately from c. 350 individuals (225 mature individuals) in 1980 to around 700 individuals (450 mature individuals) in 2017 (DCNA 2018). The most recent estimate from La Blanquilla is from 1996-1998, when the island held around 100 individuals (Sanz and Rodríguez-Ferraro 2006). On the mainland, the species was in decline in 2003 (Hilty 2003). The population in north-western Venezuela was estimated at 5,000 individuals in 2012 (V. Sanz in litt. 2016), while there are no estimates available for the north-east of the country. The current population size and trend on the mainland are thus unknown, and we are unable to determine the overall population trend for this species.
Yellow-shouldered Amazon is currently classified as Vulnerable under Criterion B1 because it has a restricted range, within which trade and habitat loss have caused declines (Collar et al. 1992). However, the species’s Extent of Occurrence (EOO) has recently been revised as 135,000 km2, based on a Minimum Convex Polygon (the smallest polygon in which no internal angle exceeds 180 degrees and which contains all the sites of occurrence) (IUCN 2001, 2012). This updated EOO figure no longer falls under the threshold of 20,000 km2, under which a species may be listed as Vulnerable under Criterion B1.
After re-calculating the EOO for Yellow-shouldered Amazon, this species may warrant a change in Red List status. Therefore, we present here our reassessment against all criteria for the species.
The initial topic on this analysis can be found here.
Criterion A – The population of Yellow-shouldered Amazon is thought to have declined in the past based on high poaching pressure and habitat loss within its range. However, data on population size and trends for this species are scarce. Currently, it is only possible to assess the rate of change for the two subpopulations on the islands of Margarita and Bonaire.
The population on Margarita increased from an initial 500 mature individuals in 1989 and stabilized at 1000 mature individuals in 2008 (Briceño-Linares et al. 2011, V. Sanz in litt. 2016). Assuming a constant rate of population change, this equates to a 100% increase over this period, or a 160% increase over the past three generations (36.9 years). On Bonaire, the population increased from 225 mature individuals in 1980 to 450 mature individuals in 2017 (DCNA 2018). This equates to an increase of c. 100% over three generations. Taken together, these two populations increased by 137% over the past three generations.
Very precautionarily, it could be assumed that the mainland population of unknown size was very large in the past and is undergoing a rapid decline, so that it has outweighed the increases in the island populations. This may be feasible, given that the mainland population was considered to be in decline in 2003 (Hilty 2003), and the western mainland population was estimated at 5,000 individuals in 2012. We do not have a figure for the eastern mainland population.
In order to be listed as Vulnerable under Criterion A4, Yellow-shouldered Amazon would have to undergo a decline of ≥ 30% over three generations. Therefore, information is urgently sought regarding the current rate of population decline on the mainland, to see whether the overall rate of decline in this species is large enough to warrant its listing under Criterion A4cd and possibly additionally A2cd+3cd.
Criterion B – Using a Minimum Convex Polygon, the Extent of Occurrence (EOO) of this species has been calculated as 135,000 km2. This is far too large for listing the species as Vulnerable and therefore, Yellow-shouldered Amazon may be considered Least Concern under this criterion. The Area of Occupancy has not been calculated; thus, the species cannot be assessed against Criterion B2.
Criterion C – The population of Yellow-shouldered Amazon is estimated to number 1,700-5,600 mature individuals. This may warrant listing the species under Criterion C, under the condition that it is declining and other conditions are met. If Yellow-shouldered Amazon should be undergoing a population decline estimated at ≥ 10 % over three generations, it may be listed as Vulnerable under Criterion C1.
The species forms several subpopulations, and there is no evidence that the number of mature individuals is fluctuating. Thus, it can only be listed under Criterion C2 if no subpopulation contains more than 1,000 mature individuals. This is the case for the islands of Margarita, La Blanquilla and Bonaire. We do not have information about the population size on Curaçao or eastern mainland Venezuela. The population on the western mainland was estimated at 5,000 individuals in 2012, equating to around 3,300 mature individuals. Considering the threats the species is facing, it cannot be ruled out that this population declined to less than 1,000 mature individuals since then. In case that the populations on Curaçao and the eastern mainland are smaller, Yellow-shouldered Amazon may be listed as Vulnerable or Near Threatened under Criterion C2a(i).
We urgently request information on the rate of population change and on the sizes of the different subpopulations, in particular up-to-date information from the mainland populations, in order to be able to assess the species against this criterion.
Criterion D – The population size and range of this species are too large for listing as Vulnerable and therefore, Yellow-shouldered Amazon may be considered Least Concern under this criterion.
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 appears that the only criteria where the species might approach or meet the threshold for Vulnerable are A2cd, and possibly additionally A3cd+4cd and C1+2a(i). To better assess the species against these criteria, we urgently request up-to-date information regarding the current population size and rate of decline of Yellow-shouldered Amazon, particularly for the populations on the mainland.
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.
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.
Briceño-Linares, J. M.; Rodríguez, J. P.; Rodríguez-Clark, K. M.; Rojas-Suárez, F.; Millán, P. A.; Vittori, E. G.; Carrasco-Muñoz, M. 2011. Adapting to changing poaching intensity of yellow-shouldered parrot (Amazona barbadensis) nestlings in Margarita Island, Venezuela. Biological Conservation 144: 1188–1193.
Collar, N.; Boesman, P.; de Juana, E.; Kirwan, G. M. 2018. Yellow-shouldered Amazon (Amazona barbadensis). 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/54748 (Accessed 13 September 2018).
Collar, N. J.; Gonzaga, L. P.; Krabbe, N.; Madroño Nieto, A.; Naranjo, L. G.; Parker, T. A.; Wege, D. C. 1992. Threatened birds of the Americas: the ICBP/IUCN Red Data Book. International Council for Bird Preservation, Cambridge, U.K.
DCNA. 2018. Bonaire’s Yearly Parrot Count. BioNews 15: 3-4.
Hilty, S. L. 2003. Birds of Venezuela. A&C Black, London, U.K.
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.
Rodríguez-Ferraro, A. 2009. Who’s who? & how we know – Genetics & Conservation. PsittaScene 21(3): 3-5.
Rojas-Suárez, F.; Rodríguez, J. P. 2015. Cotorra cabeciamarilla, Amazona barbadensis. In: Rodríguez, J. P.; García-Rawlins, A.; Rojas-Suárez, F. (eds). Libro Rojo de la Fauna Venezolana. Cuarta edición, Provita y Fundación Empresas Polar, Caracas, Venezuela.
Sanz, V.; Grajal, A. 1998. Successful reintroduction of captive-raised Yellow-shouldered Amazon parrots on Margarita Island, Venezuela. Conservation Biology 12: 430-441.
Sanz, V.; Rodriguez-Ferraro, A. 2006. Reproductive parameters and productivity of the Yellow-shouldered Parrot on Margarita Island, Venezuela: a long-term study. The Condor 108: 178-192.