Crescent-faced Antpitta (Grallaricula lineifrons): revise global status?

BirdLife species factsheet for Crescent-faced Antpitta

Crescent-faced Antpitta (Grallaricula lineifrons) is known from few localities in the Central Andes in southern Colombia (Cauca) and on the eastern slope of the Andes in Ecuador (Napo, Carchi, Cañar and Loja) (Lehmann et al. 1977, Ridgely and Tudor 1994). Its cryptic habits make it easily overlooked; the population size has thus not been quantified, but the species is considered rare to locally uncommon or fairly common (Stotz et al. 1996, Krabbe et al. 2018). Crescent-faced Antpitta occurs on relatively steep slopes in the undergrowth of epiphyte-clad humid montane forest, elfin forest and adjacent secondary woodland (Fjeldså and Krabbe 1990, Ridgely and Tudor 1994, Parker et al. 1996). It ranges from 2,900 to 3,400 m.

Agricultural expansion has led to widespread and severe deforestation of montane forest within the range, which is likely to continue (Stattersfield et al. 1998). Remaining forests are degraded as a consequence of timber extraction for charcoal production (Freile and Santander 2005). In Ecuador, the lowering of the tree-line through cutting and burning for pasture is a major threat to montane forests (del Hoyo et al. 2003). While data on population trends of Crescent-faced Antpitta are lacking, these threats are assumed to cause ongoing population declines. Nevertheless, the species might be more tolerant of patchy, degraded forests and secondary growth than assumed, and therefore less at risk than believed (Krabbe et al. 2018).

Currently, Crescent-faced Antpitta is listed as Near Threatened under Criterion B1ab(i,ii,iii,v) (BirdLife International 2018). However, this is no longer tenable because this was based on an Extent of Occurrence (EOO) value calculated as the ‘area of mapped range’. This is no longer appropriate, and the EOO should be calculated using a Minimum Convex Polygon (see 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 Crescent-faced Anpitta, the 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 Crescent-faced Antpitta is suspected to be in decline, but the rate of decline has not been estimated directly. The only known threat to the species is the loss of its forest habitat. However, a remote-sensing study found that recent forest loss within the range was negligible (potentially <1% over ten years; Tracewski et al. 2016). Assuming that the population trend is equivalent to the changes in forest cover, the suspected declines seem to be historical and the species seems to be stable over the last ten years. Therefore, Crescent-faced Antpitta may be listed as Least Concern under Criterion A.

Criterion B – The newly calculated Extent of Occurrence (EOO) for this species is 82,700 km2. This does not meet the threshold for Vulnerable (EOO < 20,000 km2). Therefore, Crescent-faced Antpitta may be listed as Least Concern under Criterion B1. The Area of Occupancy (AOO) has not been calculated and thus the species cannot be assessed against Criterion B2.

Criterion C –The population size of Crescent-faced Antpitta has not been estimated. Therefore, it cannot be assessed against this criterion. Given its large range, the population size is unlikely to fall below the threshold (10,000 mature individuals) for listing it as Vulnerable under Criterion C.

Criterion D – The population size of Crescent-faced Antpitta has not been estimated. Therefore, it cannot be assessed against this criterion. Given its large range, the population size is unlikely to fall below the threshold (1,000 mature individuals) for listing it as Vulnerable under Criterion D

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 Crescent-faced Antpitta (Grallaricula lineifrons) be listed as Least Concern. 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. 2018. Species factsheet: Grallaricula lineifrons. http://www.birdlife.org (Accessed 21 December 2018).

del Hoyo, J.; Elliott, A.; Christie, D. 2003. Handbook of the Birds of the World, Vol. 8: Broadbills to Tapaculos. Lynx Edicions, Barcelona, Spain.

Fjeldså, J.; Krabbe, N. 1990. Birds of the high Andes. Apollo Books, Copenhagen, Denmark.

Freile J. F.; Santander T. 2005. Áreas Importantes para la Conservación de las Aves en Ecuador. In: BirdLife International, Conservation International (ed.). Áreas Importantes para la Conservación de las Aves en los Andes Tropicales: sitios prioritarios para la conservación de la biodiversidad. pp. 283-370. BirdLife International, Quito, Ecuador.

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.

Krabbe, N. K..; Schulenberg, T. S.; de Juana, E. 2018. Crescent-faced Antpitta (Grallaricula lineifrons). 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/56920 (Accessed 21 December 2018).

Parker, T. A.; Stotz, D. F.; Fitzpatrick, J. W. 1996. Ecological and distributional databases. In: Stotz, D. F.; Fitzpatrick, J. W.; Parker, T. A.; Moskovits, D. K. (eds.). Neotropical bird ecology and conservation. pp. 113-436. University of Chicago Press, Chicago, U.S.A.

Ridgely, R. S.; Tudor, G. 1994. The birds of South America. University of Texas Press, Austin, Texas, U.S.A.

Stattersfield, A. J.; Crosby, M. J.; Long, A. J.; Wege, D. C. 1998. Endemic bird areas of the world: priorities for bird conservation. BirdLife International, Cambridge, U.K.

Stotz, D. F.; Fitzpatrick, J. W.; Parker, T. A.; Moskovits, D. K. 1996. Neotropical Birds: Ecology and Conservation. University of Chicago Press, Chicago, U.S.A.

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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3 Responses to Crescent-faced Antpitta (Grallaricula lineifrons): revise global status?

  1. Juan Freile says:

    Well, it seems obvious that the new way BirdLife is calculating EOO will result in downgrading lots of species, some I consider misleading. It will derive in an “inflation” of widespread threatened species in Amazonia (because BLI used or overused rates of forest loss in the entire Amazon basin) and a “deflation” of rare, narrowly endemic, forest dependent species from the Pacific lowlands and Andean slopes. In Ecuador, we estimated its EOO in a more conservative way (under 20,000 km2), which resulted in ranking it as VU.

    • Red List Team (BirdLife International) says:

      Thank you very much for your comment. We are aware that the estimate of habitat loss for Amazonian species is, to say the least, outdated. We will soon start revising deforestation rates in the ranges of forest-dependent species worldwide and will implement the results as soon as possible.
      IUCN guidelines state that the EOO has to be mapped as a Minimum Convex Polygon around the area of mapped range. The guidelines stress that this polygon needs to be continuous, and that no exceptions can be made for species with disjunct ranges. This implies that for the Crescent-faced Antpitta, the EOO will include areas of unsuitable habitat, which cannot be excluded. Please see https://www.iucnredlist.org/resources/redlistguidelines chapter 4.9 for details. The EOO measures the spatial spread of the areas occupied by the taxon, i.e. the spatial spread of the extinction risk. It does not measure the amount of occupied or suitable habitat.

  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.

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