Archived 2020 topic: Gold-ringed Tanager (Bangsia aureocincta): revise global status?

BirdLife species factsheet for Gold-ringed Tanager

Gold-ringed Tanager (Bangsia aureocincta) is endemic to Colombia, where it occurs in a small area on the Pacific slope of the West Andes. The species occupies humid and mossy cloud forests at 350-2,195 m (Renjifo et al. 2014). The population size is preliminarily placed in the band 600-1,700 mature individuals, though this may be an underestimate.

The species is threatened by the loss of its habitat. Deforestation in parts of the range has been severe in the past, but has slowed down considerably in more recent years or even reversed, with areas being reforested (Renjifo et al. 2014, Tracewski et al. 2016, Global Forest Watch 2020). Nevertheless, models of future habitat availability in the Andes of Colombia and Ecuador project 24% habitat loss by the end of the century in the altitudinal band of Gold-ringed Tanager (Renjifo et al. 2014).

Gold-ringed Tanager is currently listed as Endangered under Criterion B2ab(i,ii,iii,v) (BirdLife International 2020). However, reviewing available information regarding the distribution range and population size suggests that the species may warrant a change in Red List status (see also Renjifo et al. 2014). Therefore, it will be re-assessed against all criteria:

Criterion A – The population trend has not been estimated directly. The only threat known to the species is the loss of its habitat; yet forest loss within the range has been very low over the past ten years (< 2%; Tracewski et al. 2016, Global Forest Watch 2020; one generation length being 3.3 years; Bird et al. 2020)*. However, models revealed that available habitat in the species’s altitudinal range will decrease by c. 24% across Ecuador and Colombia by the end of this century (Renjifo et al. 2014). Therefore, the species is tentatively suspected to be in a slow decline, the rate of which does not exceed 10% over ten years. Gold-ringed Tanager therefore qualifies as Least Concern under Criterion A.   

Criterion B – The Extent of Occurrence (EOO) for this species is 8,000 km2. The maximum Area of Occupancy (AOO), as calculated by a 4 km2 grid over the area of mapped range, is 1,940 km2. These values meet the threshold for Vulnerable under Criterion B. However, in order to be listed under this criterion, at least two further conditions have to be met.

Observational records of the species are fairly continuous throughout the range (eBird 2020), and therefore the species is not severely fragmented sensu ICUN (see IUCN Standards and Petitions Committee 2019). The only threat known to the species is habitat loss. However, the effects of the very low rates of deforestation and the slow contraction in available habitat projected over the next decades are unlikely to have impacts that are severe enough to extirpate large parts of the population within the next ten years. Therefore, the species cannot be considered to occur at ≤10 locations**. Considering the small range, we can precautionarily assume that the number of locations** is slightly above 10, so that the species approaches the threshold for listing as threatened under subcriterion a. Habitat availability is projected to decline slowly until the end of the century (Renjifo et al. 2014), and subcriterion b(ii,iii) is met. The species is not known to undergo extreme fluctuations, and thus subcriterion c is not met. Overall, even though the EOO and AOO are small, Gold-ringed Tanager does not meet enough conditions to qualify as threatened under Criterion B. The species may therefore be considered Near Threatened, approaching the threshold for listing as threatened under Criterion B1ab(ii,iii)+2ab(ii,iii).

Criterion C – The population size of Gold-ringed Tanager is thought to number 600-1,700 mature individuals. This meets the threshold for listing as threatened under Criterion C. However, to do so a species must meet further conditions.

It is suspected that the species is undergoing a slow population decline due to habitat loss. A suspected decline, however, precludes a listing as threatened under Criterion C. Even though we have no direct information on the subpopulation structure, given the even spread of records throughout the range (eBird 2020) we can tentatively assume that the species forms just one subpopulation. Overall, Gold-ringed Tanager only meets two out of three conditions and can therefore not be listed as threatened under Criterion C. Nevertheless, it may be listed as Near Threatened, approaching the threshold for listing as threatened under Criterion C2a(ii).

Criterion D – The population size is preliminarily placed in the band 600-1,700 mature individuals. Assuming that the true population size is closer to the lower end of the estimate, Gold-ringed Tanager 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 suggested that Gold-ringed Tanager (Bangsia aureocincta) be listed as Vulnerable under Criterion D1. We welcome any comments on the proposed listing and specifically request up-to-date information regarding the population size.

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. By submitting a comment, you confirm that you agree to the Comment Policy.

*Bird generation lengths are estimated using the methodology of Bird et al. (2020), as applied to parameter values updated for use in each IUCN Red List for birds reassessment cycle. Values used for the current assessment are available on request. We encourage people to contact us with additional or improved values for the following parameters; adult survival (true survival accounting for dispersal derived from an apparently stable population); mean age at first breeding; and maximum longevity (i.e. the biological maximum, hence values from captive individuals are acceptable).

**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

Bird, J. P.; Martin, R.; Akçakaya, H. R.; Gilroy, J.; Burfield, I. J.; Garnett, S.; Symes, A.; Taylor, J.; Šekercioğlu, Ç.; Butchart, S. H. M. (2020). Generation lengths of the world’s birds and their implications for extinction risk. Conservation Biology online first view.

BirdLife International. 2020. Species factsheet: Bangsia aureocincta. http://www.birdlife.org (Accessed 03 April 2020).

eBird. 2020. eBird: An online database of bird distribution and abundance [web application]. eBird, Ithaca, New York. http://www.ebird.org (Accessed 03 April 2020).

Global Forest Watch. 2020. Interactive Forest Change Mapping Tool. http://www.globalforestwatch.org (Accessed 03 April 2020).

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.

IUCN Standards and Petitions Committee. 2019. Guidelines for using the IUCN Red List Categoreis and Criteria. Version 14. http://www.iucnredlist.org/documents/RedListGuidelines.pdf.

Renjifo, L. M.; Gomez, M. F.; Velasquez-Tibata, J.; Amaya-Villarreal, A. M.; Kattan, G. H.; Amaya-Espinel, J. D.; Burbano-Giron, J. 2014. Libro rojo de aves de Colombia, Volumen I: bosques humedos de los Andes y la costa Pacifica. Editorial Pontificia Universidad Javeriana e Instituto Alexander von Humboldt. Bogota D.C., Colombia.

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.

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6 Responses to Archived 2020 topic: Gold-ringed Tanager (Bangsia aureocincta): revise global status?

  1. Red List Team (BirdLife International) says:

    Global Forest Change data on tree cover loss up to 2019 have now been released and made available via Global Forest Watch. Based on these data, over ten years approximately 0.7% of tree cover with 75% canopy cover was lost from within the species’s range (Global Forest Watch 2020). This does not affect the above assessment under Criterion A.

  2. Copiado de / copied from: Alex Cortés, Juan Carlos Luna, Andrea Borrero, y Juan Lazaro Toro (2020) Evaluación de especies de aves amenazadas en Colombia / Evaluation of Threatened Birds Species in Colombia. Conservación Colombiana 27: 3-31.

    “Bangsia aureocincta ocurre a lo largo de una franja estrecha de bosque nuboso pluvial subtropical superior y montano inferior en la ladera del Pacífico de la Cordillera Occidental. El rango de elevación en cualquier sitio es típicamente pequeño, dentro de unos pocos cientos de metros de elevación, pero a través de su rango latitudinal se puede encontrar en cualquier lugar de 1,600-2,200 m (no hasta 350 m como se señaló anteriormente). La razón es que Bangsia aureocincta se encuentra en el punto de interseccion del bosque de niebla, principal en la vertiente del Pacífico de la Cordillera Occidental. Este rango de elevación específico (dentro de 100-200 m) varía latitudinalmente en su rango de 240 km de norte a sur (disminuyendo hacia el sur y más alto en el norte)

    En el punto de inicio del bosque de niebla, la vegetación tiene densidades excepcionales de epífitas y el dosel está particularmente fragmentado por las ramas que se quiebran por las cargas pesadas de epífitas que retienen mucha humedad y que podria derribar árboles enteros. Esto aumenta la penetración de la luz del sotobosque y del piso intermedio para dar como resultado una vegetación densa y mejoramiento en la oferta de recursos. Estamos de acuerdo que el tamaño de la población se coloca de forma preliminar en del rango de 600-1,700 individuos maduros, Aunque esto probablemente no sea una sobrestimación

    La especie está amenazada por la pérdida de su hábitat y altamente susceptible al rango climático y estamos de acuerdo (Renjifo 2014) en que la pérdida futura de hábitat para fines de siglo tendrá un impacto significativo en Bangsia aureocincta. En todo el AOO, Global Forest Watch observa una disminución del 0.3% en la cobertura forestal desde 2000.

    Afortunadamente, Bangsia aureocincta cuenta con varias áreas protegidas de gran importancia en sus reductos de población, incluyendo el Parque Nacional Natural Tatamá, el Parque Nacional Natural Las Orquídeas, Las Reserva de ProAves Tangaras y Gorrión de Andivia, La Reserva Natural Comunitaria Cerro El Inglés y el paso de Galápagos. Cuestionamos un solo registro de la especie en el Parque Nacional Paramillo, ya que carece de confirmación y es un inusual tipo de hábitat para la especie.

    Evaluamos lo siguiente:

    Criterio A: creemos que la tendencia de la población es una disminución lenta (amenazas moderadas y niveles crecientes de protección) y cuya tasa no supera el 10% en diez años, por lo que califica como Preocupación Menor.

    Criterio B: dado el gradiente de elevación refinado y estrecho sobre su rango, calculamos el AOO para esta especie en 760 km2 (no 1.940 km 2 ). Estos valores cumplen el umbral para Vulnerable según el Criterio 2b ( ii, iii ).

    Criterio C : listado como Casi Amenazado, C2a (ii).

    Criterio D : el tamaño de la población de 600-1,700 individuos maduros parece apropiado, por lo que aparece como Vulnerable, D1.

    ProAves recomienda que Bangsia aureocincta figure como Vulnerable en los Criterios B2b ( ii, iii ) + D1.”

  3. Copiado de / copied from: Alex Cortés, Juan Carlos Luna, Andrea Borrero, y Juan Lazaro Toro (2020) Evaluación de especies de aves amenazadas en Colombia / Evaluation of Threatened Birds Species in Colombia. Conservación Colombiana 27: 3-31.

    “Bangsia aureocincta occurs along a narrow swath of upper subtropical and lower montane pluvial cloud forest on the Pacific slope of the Western Cordillera. The elevational range at any one site is typically small – within just a few hundred meters of elevation, but across its latitudinal range it can be found anywhere from 1,600-2,200 m (not down to 350 m as noted above). The reason is that Bangsia aureocincta is found at the principal cloud inception point on the Pacific slope of the Western Cordillera. This specific elevational range (within 100-200 m) varies latitudinally across its 240 km range from north to south (decreasing to the south and highest in the north).

    At the principal cloud inception point in the montane forest this vegetation has exceptional densities of epiphytes and the canopy is particularly fragmented from heavy epiphytes burdens together with retained moisture to snap off branches and down entire trees. This increases understory and midstory light penetration to result in a dense vegetation and preferred food resources. We concur that the population size is preliminarily placed in the band 600-1,700 mature individuals, though this is not an underestimate.

    The species is threatened by the loss of its habitat and is highly susceptible to climate range and we agree with (Renjifo 2014) that future habitat loss by the end of the century will significantly impact Bangsia aureocincta. Across the AOO, Global Forest Watch notes 0.3% decrease in forest cover since 2000.

    Fortunately, Bangsia aureocincta counts on several extremely important protected areas at its population strongholds, including Tatama and Las Orquídeas National Park, Las Tangaras ProAves Reserve, Gorrión de Andivia ProAves Reserve, Reserva Natural Comunitaria Cerro El Inglés and the Galapagos pass. We question a single record of the species in Paramillo National Park as it lacks confirmation and in an unusual habitat type.

    We assessed the following:

    Criterion A – We believe the population trend is a slow decline (moderate threats and increasing levels of protection) and the rate of which does not exceed 10% over ten years so therefore qualifies as Least Concern.

    Criterion B – Given the refined and narrowed elevational gradient over its range, we calculate the AOO for this species at 760 km2 (not 1,940 km2). These values meet the threshold for Vulnerable under Criterion 2b(ii,iii).

    Criterion C – Listed as Near Threatened, C2a(ii).

    Criterion D – The population size of 600-1,700 mature individuals seems appropriate so listed as Vulnerable, D1.

    ProAves recommends that Bangsia aureocincta be listed as Vulnerable under Criteria B2b(ii,iii)+D1.”

  4. Red List Team (BirdLife International) says:

    Many thanks to everyone who has contributed to this discussion. We greatly appreciate the time and effort invested by so many people in commenting. The window for consultation is now closed. We will analyse and interpret the new information and post a preliminary decision on this species’s Red List status on this page in early July.

    Thank you once again,
    BirdLife Red List Team

  5. Red List Team (BirdLife International) says:

    Preliminary proposal

    Based on available information, our preliminary proposal for the 2020 Red List would be to adopt the proposed classification 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 2020 Red List categories will be published on the BirdLife and IUCN websites in December 2020/January 2021, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  6. Red List Team (BirdLife International) says:

    Recommended categorisation to be put forward to IUCN

    The final categorisation for this species has not changed. Gold-ringed Tanager is recommended to be listed as Vulnerable under Criterion D1.

    Many thanks for everyone who contributed to the 2020 GTB Forum process. The final 2020 Red List categories will be published on the BirdLife and IUCN websites in December 2020/January 2021, following further checking of information relevant to the assessments by both BirdLife and IUCN.

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