Three-toed Jacamar (Jacamaralcyon tridactyla): revise global status?

BirdLife species factsheet for Three-toed Jacamar

Three-toed Jacamar (Jacamaralcyon tridactyla) occurs in small numbers at a few sites in south-eastern Brazil. It is found in the Río Paraíba valley in Rio de Janeiro state and the dry regions of east Minas Gerais at elevations between 240 and 1,100 m. While older records from Espírito Santo, São Paulo and Paraná suggest that the range has declined in the past, recent records from Minas Gerais have widened the known distribution (Machado et al. 1998, Silveira and Rocha Nobre 1998, Ribon et al. 2002, Duarte et al. 2014), and suggest that further populations may exist within this area. Overall however, Three-toed Jacamar was considered very common in the early and mid-19th century and must have suffered a very substantial decline in numbers. It is now local even in the core of its range. The total population is placed in the band 250-999 mature individuals, equating to roughly 350-1,500 individuals (BirdLife International 2019).

Three-toed Jacamar is restricted to small, isolated patches of dry forest, where it is found along forest edges, streams, roads and tracks. It is dependent on earth banks for nesting-cavities (Silveira and Rocha Nobre 1998). The species can persist in degraded areas with bushes, vines and scattered trees, where the original vegetation has been replaced, if a native understorey remains (Machado and Lamas 1996, Silveira and Rocha Nobre 1998). It is often found in heavily disturbed sites near urban areas (Tobias et al. 2019).

Although capable of surviving in some degraded woodlots, this species has undergone a major decline in the past, such that the remaining population is believed to be very small. Widespread and continuing habitat destruction are thought to be responsible for the decline in numbers and range of this species. In addition, its specialised habitat requirements ensure that it is absent from many degraded woodlots. The species is thus vulnerable to the effects of small population size, such as local extinctions and inbreeding.

Three-toed Jacamar is currently listed as Vulnerable under Criterion D1 (BirdLife International 2019), indicating a small or restricted population. However, incorporating new information on population trends and the subpopulation structure, 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 – The population of Three-toed Jacamar it assumed to be in decline, but the rate of decline has not been estimated directly. Tracewski et al. (2016) measured the forest loss within the species’s range between 2000 and 2012 as c. 6,300 km2. This roughly equates to a rate of forest loss of 9.8% over three generations (18.6 years) for this species. Three-toed Jacamar seems to be able to tolerate forest fragmentation, degradation and disturbance (Machado and Lamas 1996, Silveira and Rocha Nobre 1998); however, habitat loss remains a major threat as it is thought to be responsible for drastic population declines in the past (Tobias et al. 2019). Hence, we can tentatively assume that the species is in decline, but likely at a slower rate as the forest cover; thus Three-toed Jacamar is inferred to have undergone a reduction of 1-9% over the past 18.6 years. Overall, the rate of decline is too slow to approach the threshold for Vulnerable under this criterion. Therefore, Three-toed Jacamar may be listed as Least Concern under Criterion A.

Criterion B – The Extent of Occurrence (EOO) for this species is 466,000 km2. This does not meet the threshold for Vulnerable (EOO < 20,000 km2). Therefore, Three-toed Jacamar may be listed as Least Concern under Criterion B1. The Area of Occupancy (AOO) has not been calculated and Three-toed Jacamar cannot be assessed against Criterion B2.

Criterion C – The global population is estimated to number 250-999 mature individuals. This may warrant listing the species under Criterion C, given it is considered to be declining, as long as other conditions are met. With its suspected rate of decline per Tracewski et al. (2016), it could warrant listing as Near Threatened under Criterion C1, but no higher because the population change has not been directly estimated. The species is spread out over several subpopulations, which are likely very small. Assuming that the true population size is closer to the lower end of the estimate, it is highly likely that no subpopulation consists of more than 250 mature individuals. Therefore, Three-toed Jacamar may be listed as Endangered under Criterion C2a(i).

Criterion D – The population size is estimated to number 250-999 mature individuals. Therefore, Three-toed Jacamar 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 Three-toed Jacamar (Jacamaralcyon tridactyla) be listed as Endangered under Criterion C2a(i). 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.

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. 2019. Species factsheet: Jacamaralcyon tridactyla. http://www.birdlife.org (Accessed 13 February 2019)

Duarte, T. B. F.; de Castro Pena, J. C.; Rodrigues, M. 2014. Novo registro do cuiteláo Jacamaralcyon tridactyla (Vieillot, 1817) em fragmento florestal urbano de Belo Horizonte, Minas Gerais. Atualidades Ornitológicas 182: 24.

Machado, A. B. M.; da Fonseca, G. A. B.; Machado, R. B.; Aguiar, L. M. De S.; Lins, L. V. 1998. Livro Vermelho das espécies ameaçadas de extinção da fauna de Minas Gerais. Fundação Biodiversitas, Belo Horizonte, Brazil.

Machado, R. M.; Lamas, I. R. 1996. Avifauna associada a um relorestamento de eucalipto no município de Antônio Dias, Minas Gerais. Ararajuba 4: 15-22.

Ribon, R.; Whitney, B. M.; Pacheco, J. F. 2002. Discovery of Bahia Spintail Synallaxis cinerea in north-east Minas Gerais, Brazil, with additional records of some rare and threatened montane Atlantic Forest birds. Cotinga 17: 46-50.

Silveira, L. F.; Rocha Nobre, H. 1998. New records of Three-toed Jacamar Jacamaralcyon tridactyla in Minas Gerais, Brazil, with some notes on its biology. Cotinga: 47-51.

Tobias, J.; Züchner, T.; de Melo Júnior, T. A.; Kirwan, G. M. 2019. Three-toed Jacamar (Jacamaralcyon tridactyla). 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/55941 (Accessed 13 February 2019).

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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1 Response to Three-toed Jacamar (Jacamaralcyon tridactyla): revise global status?

  1. 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.

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