BirdLife species factsheet for Bogota Rail
This discussion was first published as part of the 2020 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 2021 Red List update this post remains open and the date of posting has been updated.
Bogota Rail is endemic to Colombia, where it occurs on the Ubaté-Bogotá plateau in the East Andes. It inhabits savannah and páramo marshes and swamps at an elevation of 2,500-4,000 m. The species is localised, but fairly common in suitable habitat (Taylor and Sharpe 2020). Based on an observed population density of 68 individuals/km2 at Laguna de Tota and under the assumption that 50% of the remaining habitat is occupied, the total population has been estimated at 5,600 individuals (Renjifo et al. 2016). This roughly equates to 3,700 mature individuals. To account for uncertainty, the population is here placed in the band 2,500-9,999 mature individuals.
Recent observations of main populations indicate a decrease in numbers (Renjifo et al. 2016, L. Rosselli in litt. 2020). Bogota Rail is heavily threatened by the loss and degradation of its habitat through drainage of wetlands, agricultural encroachment and subsequent pollution by effluents and agrochemicals, as well as by predation of adults and nestlings by feral dogs (Lonzano 1993, Renjifo et al. 2016, Taylor and Sharpe 2020).
Bogota Rail is currently listed as Endangered under Criteria B1ab(i,ii,iii,iv,v); C2a(i) (BirdLife International 2020). However, new information regarding the population size and distribution range suggests that the species may warrant a change in Red List status. Therefore, it will be re-assessed against all criteria:
Criterion A – The species is undergoing a population decline as suitable habitat within its range is disappearing. The rate of decline has not been quantified, but is here tentatively placed in the band 10-19% over ten years (one generation length being 2.4 years; Bird et al. 2020)*. The species is therefore listed as Least Concern under Criterion A.
Criterion B – The newly calculated Extent of Occurrence (EOO) for this species is 16,600 km2. The maximum Area of Occupancy (AOO), calculated as a 4 km2 grid over the area of mapped range, is 3,144 km2. The EOO therefore meets the threshold for listing as Vulnerable under Criterion B1. However, in order to be listed as threatened under this criterion, a species needs to fulfil at least two further conditions.
The species is thought to form one subpopulation (Renjifo et al. 2016). It is therefore not severely fragmented sensu IUCN (IUCN Standards and Petitions Committee 2019). The most serious threats to the species are the drainage of its wetland habitat, pollution and predation by feral dogs (Renjifo et al. 2016, Taylor and Sharpe 2020). These threats can potentially impact a relatively large area and consequently a relatively large part of the population at once. The number of locations** of occurrence is therefore placed in the band 6-10, and condition a is met at the level of Vulnerable. Habitat degradation is proceeding rapidly within the range, and observations report population declines at several sites (Renjifo et al. 2016, L. Rosselli in litt. 2020). Bogota Rail thus meets condition b(ii,iii,v). There is no evidence of extreme fluctuations in the distribution range or population size, and condition c is not met. Consequently, the species qualifies for listing as Vulnerable under Criterion B1ab(ii,iii,v).
Criterion C – The global population is placed in the band 2,500-9,999 mature individuals. This meets the threshold for Vulnerable under Criterion C; however in order to be listed under this criterion further conditions must be fulfilled.
In parts of the range, the population has been observed to decline (Renjifo et al. 2016, L. Rosselli in litt. 2020). Even though trend data for the rest of the population are lacking, we can infer that the global population is undergoing a decline. The species is restricted to wetlands which are separated by only short distances, and hence it appears that the species forms just one subpopulation (Renjifo et al. 2016). Bogota Rail may therefore be listed as Vulnerable under Criterion C2a(ii).
Criterion D – The population size and range are too large to warrant listing as threatened under Criterion D and therefore, the species is considered Least Concern under this criterion.
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 Bogota Rail (Rallus semiplumbeus) be listed as Vulnerable under Criteria B1ab(ii,iii,v); C2a(ii). We welcome any comments on the 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. 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.
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: Rallus semiplumbeus. http://www.birdlife.org (Accessed 14 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 Categories and Criteria. Version 14. http://www.iucnredlist.org/documents/RedListGuidelines.pdf.
Lozano, I. E. 1993. Observaciones sobre la ecología y el comportamiento de Rallus semiplumbeus en el Humedal de la Florida, Sabana de Bogotá.
Renjifo, L. M.; Amaya-Villarreal, A. M.; Burbano-Giron, J.; Velasquez-Tibata, J. 2016. Libro rojo de aves de Colombia, Volumen II: Ecosistemas abiertos, secos, insulares, acuaticos continentales, marinos, tierras altas del Darien y Sierra Nevada de Santa Marta y bosques humedos del centro, norte y oriente del pais. Editorial Pontificia Universidad Javeriana e Instituto Alexander von Humboldt. Bogota, Colombia.
Taylor, B.; Sharpe, C. J. 2020. Bogota Rail (Rallus semiplumbeus), version 1.0. In: del Hoyo, J.; Elliott, A.; Sargatal, J.; Christie, D. A.; de Juana, E. (eds.). Birds of the World. Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.bograi1.01 (Accessed 15 April 2020).