Archived 2020 topic: Bare-throated Bellbird (Procnias nudicollis): downlist from Vulnerable to Near Threatened?

This discussion was first published as part of the 2016 Red List update. At the time a decision regarding its status was pended, but to enable potential reassessment of this species as part of the 2020 Red List update this post remains open and the date of posting has been updated.

BirdLife species factsheet for Bare-throated Bellbird

Bare-throated Bellbird is endemic to the Atlantic forest (Snow and Sharpe 2016). It is found in eastern Brazil, north-eastern Argentina and eastern Paraguay. The species is listed as Vulnerable under A2cd+3cd+4cd. The population is provisionally estimated at 2,500-9,999 mature individuals and a rapid and on-going population decline is suspected owing to habitat loss and trapping for the cage-bird trade.

The population has unquestionably declined owing to deforestation and heavy trapping pressure for the cage-bird trade, particularly in Brazil (Brooks et al. 1993, Tobias et al. 1993, Ridgely and Tudor 1994, M. Guimarães Diniz in litt. 2003). Trapping pressure may be particularly heavy in southern Bahia, São Paulo and Santa Catarina and the population size is therefore difficult to assess in these areas (F. Olmos in litt. 2003). Numerous individuals were seen in cages between Serra das Lontras and Una Biological Reserve, southern Bahia (A. C. De Luca in litt. 2007). In north-east Paraguay deforestation was 20% between 1997 and 2001, and appears to be continuing at a similar rate. The Paraguayan population is also coming under increasing pressure from trapping (historically a localised threat), with both males and females readily available in Asunción every year. Agricultural conversion and deforestation for mining and plantation production historically threatened its habitat (Fearnside 1996). Key threats are urbanisation, industrialisation, agricultural expansion, colonisation and associated road-building (Dinerstein et al. 1995).

In the Brazilian Red List assessment for birds (MMA 2014) this species is listed as Near Threatened.

Information on the species’s population size and trends in Paraguay and Argentina is sought. Is the population size reduction likely to be <30% over 14 years (three generations)?

The species was previously considered Near Threatened but was uplisted to Vulnerable in 2004 owing to increased awareness of rapid rates of habitat destruction and trapping pressure (Snow and Sharpe 2016). Based on the Brazilian Red List assessment of this species, should the species now be considered Near Threatened globally? Confirmation that the rate of population reduction is likely to be <30% over 14 years could qualify the species for downlisting to Near Threatened under criterion A2cd+3cd+4cd.

Comments on the proposed downlisting are welcome.
References:

Brooks, T. M.; Barnes, R.; Bartrina, L.; Butchart, S. H. M.; Clay, R. P.; Esquivel, E. Z.; Etcheverry, N. I.; Lowen, J. C.; Vincent, J. 1993. Bird surveys and conservation in the Paraguayan Atlantic forest: Project CANOPY ’92 final report. BirdLife International, Cambridge, U.K.

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

Fearnside, P. 1996. Brazil. In: Harcourt, C.S.; Sayer, J.A. (ed.) The conservation atlas of tropical forests: the Americas, pp. 229-248. Simon & Schuster, New York and London.

MMA (2014) Lista Nacional Oficial de Espécies da Fauna Ameaçadas de Extinção. Portaria No 444, de 17 de dezembro de 2014. Diário Oficial da União – Seção 1. Nº 245, quinta-feira, 18 de dezembro de 2014.

Snow, D. & Sharpe, C.J. (2016). Bare-throated Bellbird (Procnias nudicollis). 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.

Tobias, J. A.; Catsis, M. C.; Williams, R. S. R. 1993. Notes on scarce birds observed in southern and eastern Brazil: 24 July – 7 September 1993.

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15 Responses to Archived 2020 topic: Bare-throated Bellbird (Procnias nudicollis): downlist from Vulnerable to Near Threatened?

  1. Rob Clay says:

    In Paraguay the species is primarily found in the northern part of Eastern Paraguay, in Atlantic Forest in Canindeyú and San Pedro departments, with a few birds also recorded in gallery forest in the Cerrado of Concepcion department. The only population which seems likely to be healthy is that found within the 64,000 ha Reserva Natural del Bosque Mbaracayú in Canindeyú department (which has about 57,000 ha of forest). All other forest areas within its range in NE Paraguay are small, degraded and increasily fragmented/isolated. Although there is a Zero Deforestation law in effect in Eastern Paraguay, illegal forest clearance and timber extraction still occurs (perhaps especially within the range of the species). At least in recent decades, the species appears to have always been uncommon to rare in the forests of SE and easternmost Paraguay – and there have been few, if any, records of the species in this area in recent years. The species still occurs in trade. For instance, I recently saw a photo of an immature male at a private zoo, which can only have come from the wild in recent years.

  2. I’m not familiar with the situation on the Brazilian coast, but in the interior Atlantic forest (Argentina, Paraguay) everything indicates that the population is declining (especially because of deforestation in Paraguay and lack of reserves, destruction of sites like Yaguareté Forest where there were good populations 15 years ago). It is very rare in Argentina, only appears at certain times of year, apparently passing through. So the parks and reserves in the province of Misiones (Argentina) are only contributing to movements (of a few individuals) and not to stable populations. I don’t think it should be downlisted; in this part of the world, it should be “endangered”.

  3. James Westrip (BirdLife) says:

    Based on available information, our proposal for the 2016 Red List would be to pend the decision on this species and keep this discussion open until 2017, while leaving the current Red List category unchanged in the 2016 update.

    Final 2016 Red List categories will be published on the BirdLife and IUCN websites in early December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  4. Kevin M. Flesher says:

    This species is abundant in parts of our reserve, especially in the Pacange forest (part of 13,000 ha forest that extends beyond the 3400 ha Reserva Ecologica Michelin). On days when the birds are actively calling, one can hear them throughout the forest, using all forest habitats from lightly logged primary forest to young (14-18 year old) secondary forest. The reserve consists of three principal forest fragments and suffered intensive hunting and bird capturing pressure as recently as 2005, but we have since been able to eliminate most of this pressure, reducing the impact to the forest edge. Prior to the creation of the reserve I did not hear bell birds calling in the Pancada Grande, Vila 5 or Luis Inacio forests and it has taken a decade for them to re-colonize these forests, even though the fragmentation distances between the reserve forests is no more than 400 m and the matrix one of rubber plantations (now abandoned). Recently (staring in 2016) I have noticed that bell birds are calling throughout the Luis Inacio and Vila 5 forests, but I have yet to hear them in the Pancada Grande forest (which is closer to the highway, towns, and has a dense rural population along its boundary). My conclusions in our reserve are: 1. that the species appears to adapt well to secondary forest in all stages of development; 2. can apparently reach high population abundances in the mosaic of secondary and heavily logged forests; 3. can recover well with protection, but that this takes some time – a decade in this case and still ongoing; 4. that the species appears to be able to cross a matrix of rubber groves, although I have never seen or heard it in this habitat; 5. is not, as of yet, inhabiting the abandoned rubber groves, even with an effective guard patrol system.

    People continue to trap the species in the region and periodically I hear caged birds calling in the town of Itubera (although it has been a few years now that I have not heard any in town). However, it seems that the birds do not last long in captivity as the calling stops from particular houses after several months. Whether the bird dies or people sell them I do not know. No state or federal environmental law enforcement in the region. I have no information on bell birds from other forests in the region as I have mostly worked in the reserve forests over this past decade.

  5. Hannah Wheatley (BirdLife) says:

    Preliminary proposals

    Based on available information, our proposal for the 2017 Red List would be to pend the decision on this species and keep this discussion open until 2018, while leaving the current Red List category unchanged in the 2017 update.

    Final 2017 Red List categories will be published on the BirdLife and IUCN websites in early December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  6. Since I wrote the entry above, we have heard bell birds in the abandoned rubber groves of the Reserva Ecologica Michelin, Itubera, Bahia and they continue to expand into the reserve’s secondary forests where I had never heard them before. The abandoned rubber groves consist of 30+ year old rubber trees with pioneer vegetation in the inter-rows. In 270 of the 600 ha of this habitat in the reserve, we have an enrichment planting program in which we have planted 100,000 trees of >215 species which will hopefully serve to increase the carrying capacity of these areas for the bell bird and other species. The bell bird colonization of these agroforest areas and secondary forests suggests that the species is flexible in its habitat use in this part of the Atlantic forest and that the bird trade rather than habitat degradation is the principal cause of the species decline in this region. The expansion of the species in the abandoned rubber groves has been quite quick and this is perhaps because all rubber tapping stopped after 2014 and few people now enter these areas. We have seen this with other species as well (e.g. Crax blumenbachii) which have expanded their ranges outside of the principal forests once rubber tapping stopped. The conservation perspective for bell birds in our reserve is good.

  7. Ricardo Cavalieri says:

    On ebird (annually) and wikiaves its records are not few.

  8. Claudia Hermes (BirdLife International) says:

    Based on available information, our proposal for the 2018 Red List would be to pend the decision on this species and keep this discussion open until 2019, while leaving the current Red List category unchanged in the 2018 update.
    Final 2018 Red List categories will be published on the BirdLife and IUCN websites in November, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  9. Hannah Wheatley (BirdLife) says:

    As part of next year’s comprehensive Red List update, we will be undertaking a revision of species’s generation lengths. Given that a change in generation length could affect this species’s Red List assessment, our proposal for the 2019 Red List is to pend the decision on this species and keep the discussion open until 2020, while leaving the current Red List category unchanged in the 2019 update.

    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.

  10. Red List Team (BirdLife International) says:

    As stated above, this proposal was originally posted in 2016. Since then, more information has become available and the species has been reassessed. The new assessment is presented below.

    Criterion A:
    This species’s generation length has been re-estimated at 5.54 years, based on the methods of Bird et al. 2020. This means that reductions should be assessed over a period of 17 years (three generations) for assessment under Criterion A.

    Over 17 years from 2002 to 2019, approximately 14% of tree cover with at least 50% canopy cover was lost from within the species’s range (Global Forest Watch 2020). The species is also threatened by trapping, but there is no data to indicate the impact on the population size. Assuming that trapping may have contributed an additional 10% decline, the species’s population size is tentatively assumed to have undergone a reduction of up to 24% over the past three generations (17 years), and is assumed to continue to decline at the same rate. The species is therefore assessed as Near Threatened under Criterion A. However, if further evidence suggests that the population may have declined by over 30% since 2003, the species may be retained as Vulnerable under this criterion.

    Criterion B:
    Based on the area of a minimum convex polygon around the species’s range, the extent of occurrence is inferred to be 2,100,000 km2. This is far too large for the species to qualify as threatened under Criterion B1. The area of occupancy is not known, and the species has a localised distribution, but given the size of the range, is assumed to be too large for the species to qualify as threatened under Criterion B2. The species is assessed as Least Concern under Criterion B.

    Criterion C:
    The species’s population size is not well known. It is locally relatively common in Brazil (F. Olmos in litt. 2003) and Paraguay (especially in Canindeyú, San Pedro, and Amambay) (A. Bodrati in litt. 2007), but rare in many sites and rare in Argentina (Bodrati and Cockle 2006). In Argentina, there are suspected to be fewer than 250 mature individuals (MAyDS and Aves Argentinas 2017).

    A survey using line transects and acoustic-based distance sampling in primary forest in Pico do Marumbi State Park, Parana, estimated 15 adult males per km2 (95% CI 11.9-18.7; Oliveira 2012). It is assumed that the number of adult males represents one third of the total number of individuals.

    Based on the area of tree cover within the range with at least 75% canopy cover in 2010 (c.345,000 km2; Global Forest Watch 2020), a population density of 35.7-56.1 individuals per km2 (Oliveira 2012) and assuming 1% of the tree cover is occupied, the population size is tentatively suspected to be in the range 123,165-193,545 individuals, roughly equating to 82,110-129,030 mature individuals and here placed in the band 80,000 – 130,000 mature individuals.

    The subpopulation structure is not known.

    Based on this population estimate, the species is here assessed as Least Concern under Criterion C. However, if there is evidence to suggest that the population size is less than 10,000 mature individuals, AND that there is only one subpopulation, or that the largest subpopulation has no more than 1,000 mature individuals, then the species could qualify for Vulnerable under this Criterion.

    Criterion D:
    Based on the population estimate described above, the population size is much larger than 1,000 mature individuals. The species is assessed as Least Concern under this criterion.

    Criterion E:
    No quantitative analysis of extinction risk has been undertaken. The species cannot be assessed under this criterion.

    Overall assessment:
    Based on the above assessment, it is proposed to list the species as Near Threatened, approaching the thresholds for Criteria A2+3+4.

    Comments on this proposal are welcome. We particularly welcome further information on the species’s likely rate of decline, population size and subpopulation structure.

    References:
    Bird, J. P., Martin, R., Akçakaya, H. R., Gilroy, J., Burfield, I. J., Garnett, S. G., Symes, A., Taylor, J., Şekercioğlu, Ç. H. and Butchart, S. H. M. 2020. Generation lengths of the world’s birds and their implications for extinction risk. Conservation Biology in prep.

    Bodrati, A.; Cockle, K. 2006. New records of rare and threatened birds from the Atlantic forest of Misiones, Argentina. Cotinga 26: 20-24.

    Global Forest Watch. 2020. Interactive Forest Change Mapping Tool. Available at: http://www.globalforestwatch.org/.

    Ministerio de Ambiente y Desarrollo Sustentable (MAyDS) & Aves Argentinas. 2017. Categorización de las Aves de la Argentina según su estado de conservación.

    Oliveira, S. L. 2012. Ciclo reprodutivo e densidade populacional da araponga (aves: Cotingidae): Uma abordagem metodológica. Post-graduate program in ecology and conservation, Federal University of Paraná .

  11. Vagner Cavarzere says:

    Based on criterion A4: An observed, estimated, inferred, projected or suspected population reduction where the time period must include both the past and the future (up to a max. of 100 years in future), and where the causes of reduction may not have ceased OR may not be understood OR may not be reversible, it is important to notice the species was present on interior semi deciduous Atlantic Forest in São Paulo and Paraná states, Brazil (Willis, 2003; Straube, 2016). Few recent surveys on those areas have recorded the species. When present, it was found on larger remnants and suggest 30% population reduction (Cavarzere et al., 2012) over 30 years.
    Concerning it may have declined by over 30% since 2003, that some localities it was found in the 1980s (e.g. Presidente Venceslau, Willis [2003]), where habitat modification extirpated large forests and where no protected areas exist, and citizen scientists have not documented the species in interior forests (although it may still be present), it may be suggested the species falls under the Vulnerable category.

    Cavarzere, V., Marcondes, R. S., Moraes, G. P., Donatelli, R. J. 2012. Comparação quantitativa da comunidade de aves de um fragmento de floresta semidecidual do interior do Estado de São Paulo em intervalo de 30 anos. Iheringia, Série Zoologia 102: 384-393.
    Straube, F. C. 2016. Ruínas e urubus: história da ornitologia no Paraná.
    Período de Chrostowski, 2 (1910). Hori, Curitiba.
    Willis, E. O. 2003. Aves do Estado de São Paulo. Divisa, Rio Claro.

  12. Samuel Lopes Oliveira says:

    Regarding the Criterion C, where the population estimative generated in my Master’s project is cited. I do not recommend extrapolating this value within the entire range of the species. Specially because the area we sampled is part of the biggest Atlantic Forest remnant and represents high quality habitat for the species. For instance, the results would be lower if the same method were applied in the Pró-Mata area, in the Rio Grande do Sul state, where a population can be found in the breeding season, but it is noticiably smaller by my personal observations. Thus, for a better estimative, this method should be applied in different areas with stabilished breeding populations. Another important point it that it is only feasible to generate population estimatives during the breeding season, at this time of the year the individuals are concentrated in the highlands, meaning that the wintering areas (lowlands) shoud not be consider when extrapolating the results.

  13. 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

  14. 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.

  15. Red List Team (BirdLife International) says:

    Recommended categorisation to be put forward to IUCN

    The final categorisation for this species has not changed. Bare-throated Bellbird is recommended to be listed as Near Threatened, approaching the threshold for listing as threatened under Criterion A2cd+3cd+4cd.

    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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