Archived 2018 topic: Rusty-flanked Crake (Laterallus levraudi): revise global status?

BirdLife species factsheet for Rusty-flanked Crake: http://datazone.birdlife.org/species/factsheet/rusty-flanked-crake-laterallus-levraudi

The Rusty-flanked Crake occurs on the lower Caribbean slope of north-west Venezuela, in eastern Zulia (V. Morón-Zambrano in litt. 2012), Barinas, Portuguesa, Falcón, Lara, Yaracuy, Carabobo, Aragua, Distrito Federal and Miranda. Until 1995, the only post-1946 records were from Yacambú (Lara), Morrocoy (Falcón) (Lentino and Goodwin 1991) and Embalse de Taguaiguai (Aragua). However, surveys in 1995-1996 identified seven new localities in east Falcón and west Carabobo (Boesman 1997). The first records for Barinas and Portuguesa were in 1998, with subsequent records from eastern Zulia (V. Morón-Zambrano in litt. 2012), and by 2012 the species was known from 32 localities (Sharpe et al. 2001, Hilty 2003, V. Morón-Zambrano in litt. 2012, Sharpe and Ascanio 2015, Taylor et al. 2015). The population was estimated at more than 1,000 individuals (Sharpe and Ascanio 2015) and was placed in the band 250-999 mature individuals. The population has been assumed to be declining due to loss and degradation of wetland habitats, and to be divided into subpopulations of no more than 250 mature individuals. The species is therefore listed as Endangered under Criterion C2a(i) (see BirdLife International 2017).

The Rusty-flanked crake is now known from a much larger and more contiguous distribution than it was previously, and it has been suggested that deforestation along the eastern flank of the Andes, together with the construction of dykes and pools for watering cattle, has allowed the species to spread southwards through Falcón, Yaracuy and Barinas (Sharpe et al. 2001). The Venezuelan Red Data Book (Sharpe and Ascanio 2015) states that the population size could have been underestimated, and given the contiguous distribution of the species, it is unlikely that its population is composed of small subpopulations of up to 250 mature individuals only (C. Sharpe in litt. 2017).

Therefore, It may be unwarranted to retain this species as Endangered under its current criteria string, and as such the species has been re-assessed against all criteria based on current best information.

Criterion A – Current information does not suggest that the species has undergone a population size reduction of 30% or more across three generations so the species does not approach the threshold for Vulnerable under this criterion. The species therefore qualifies for listing as Least Concern under Criterion A.

Criterion B – The species’s extent of occurrence (EOO) and area of occupancy (AOO) do not approach the thresholds for listing as Vulnerable under this criterion. The species therefore qualifies for listing as Least Concern under Criterion B.

Criterion C – The species’s population size has previously been placed in the band of 250-999 mature individuals. Although it has more recently been suggested that this estimate is likely to be an underestimate, the population size is unlikely to exceed 2,500 mature individuals and so it falls within the population threshold for listing as Endangered under Criterion C. Although the species appears to have expanded its range due to deforestation, it remains threatened by destruction and degradation of its wetland habitat and its overall population is considered to be declining (Sharpe and Ascanio 2015). We do not have a quantitative estimate or projection of the rate of continuing decline and so we are unable to assess the species under Criterion C1.  The population is now considered to be more contiguous than previously thought and it is no longer thought likely that all subpopulations hold no more than 250 individuals, but the population may be divided into two subpopulations of less than 1,000 mature individuals each (C. Sharpe in litt. 2017), qualifying the species for listing as Vulnerable under Criterion C2a(i). The species therefore qualifies for listing as Vulnerable under Criterion C.

Criterion D –The species’s population size has previously been placed in the band of 250-999 mature individuals, which would qualify the species for listing as Vulnerable under Criterion D. However, it has been suggested that this figure is an underestimate (Sharpe and Ascanio 2015), and the species thus no longer qualifies for listing as Vulnerable under Criterion D.

Criterion E – To the best of our knowledge, no quantitative assessment of the probability of extinction has been conducted for Rusty-flanked crake, and so it cannot be assessed against this criterion.

Therefore, it is proposed that Rusty-flanked crake be listed as Vulnerable under Criterion C2a(i). We welcome any comments on this proposed downlisting.

Please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of the species’s Red List status. Therefore, please make sure your comments are about the proposed listing.

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 (2017) Species factsheet: Laterallus levraudi. Downloaded from http://www.birdlife.org on 21/12/2017.

Boesman, P. (1997) Recent observations of the Rusty-flanked Crake Laterallus levraudi. Cotinga 39-42.

Hilty, S.L. (2003) Birds of Venezuela. Princeton Univ. Press. Princeton and Oxford.

Lentino, M. and Goodwin, M.L. (1991) Lista de las aves del Parque Nacional Morrocoy, Refugio de Fauna de Silvestre de Cuare y areas Aledaña, Estado Falcón, Venezuela. Sociedad Conservacionista Audubon de Venezuela, Caracas.

Sharpe, C. J., Ascanio-Echeverría, D. and Rodríguez, G.A. (2001) Further range extensions and noteworthy records for Venezuelan birds. Bulletin of the British Ornithologists’ Club 121: 50-62.

Sharpe, C.J. and Ascanio, D. (2015) Cotarita de costados castaños, Laterallus levraudi. In: Rodríguez, J.P., García-Rawlins, A. and Rojas-Suárez, F. (eds), Libro Rojo de la Fauna Venezolana. Cuarta edición, Provita & Fundación Empresas Polar, Caracas, Venezuela.

Taylor, B., Sharpe, C.J. and Boesman, P. (2015) Rusty-flanked Crake (Laterallus levraudi). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. and de Juana, E. (eds), Handbook of the Birds of the World Alive, Lynx Edicions, Barcelona.

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3 Responses to Archived 2018 topic: Rusty-flanked Crake (Laterallus levraudi): revise global status?

  1. Chris Sharpe says:

    Laterallus levraudi’s range is now known to be considerably larger and more contiguous than when the last global assessment was made – and as depicted in the BirdLife map. There are now records E of the Andes as far south as Barinas and W of them from the Maracaibo Basin (resumé in my 2015 RDB update [which regrettably was limited to a text revision, not category change]). Indeed, post-2015 observations indicate that the range is more extensive still (eBird 2018). The assignation of EN hangs on the size of sub-populations and, given that the range is essentially not fragmented, I am not sure we can really consider these to exist, except tenuously E and W of the Andes (though crakes are notoriously nomadic). In that case, I suspect that the category that best fits for now (under the precautionary principle) would be VU C2a(i), assuming that E and W sub-populations are isolated and that they comprise fewer than 1000 mature individuals.

    eBird (2018) An online database of bird distribution and abundance [web application]. eBird, Ithaca, New York. Available at: http://www.ebird.org.

    Sharpe, C.J. & Ascanio, D. (2015) Cotarita de costados castaños, Laterallus levraudi. In: Rodríguez, J.P., García-Rawlins, A. & Rojas-Suárez, F. (eds), Libro Rojo de la Fauna Venezolana. Cuarta edición, Provita & Fundación Empresas Polar, Caracas, Venezuela. Available at: http://animalesamenazados.provita.org.ve/content/cotarita-de-costados-castanos

  2. Chris Sharpe says:

    Somebody who could comment on this species with more authority than I is Vilisa Morón of Universidad Simón Bolívar. In 2012, she completed a thesis on Laterallus in Zulia State, the results of which have not yet been published, but she was kind enough to allow me to reference her work in the 2015 national RDB update.

  3. Claudia Hermes (BirdLife International) says:

    Based on available information, our preliminary proposal for the 2018 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 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.

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