Santa Marta Warbler (Myiothlypis basilica): Revise global status?

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4 Responses to Santa Marta Warbler (Myiothlypis basilica): Revise global status?

  1. Neither population density nor population trends have been estimated for this species. There is no information that may suggest that density estimates for this species are comparable to other congeners such as M. nigrocristata or M. luteoviridis. However, this species is rather rare and hence it is presumed to occur at lower densities than other Myiothlypis.

    A recent evaluation of the risk of extinction of Santa Marta Warbler suggest that remaining habitat would cover 462 km2 (Renjifo et al. 2016), and therefore, the AOO that appears in Annex 1 is at best, an overestimation. The AOO of this species is probably below 500 km2, and it has not yet been reported to occur in more than 1o localities (Córdoba-Córdoba 2016, Renjifo et al. 2016). Given that native forest above 2000 m asl is still severely fragmented on the Santa Marta Mountains and that forest cover seems not to be increasing throughout its range, the species should not be downlisted until convincing evidence of a reverting declining trend–in its population, AOO or habitat quality–is documented.

    References:
    ** Córdoba-Córdoba, S. (2016). Myiothlypis basilica. In Libro rojo de las aves de Colombia vol. II: especies acuáticas de ecosistemas abiertos y secos, tierras altas del Darién, Sierra Nevada de Santa Marta e insulares (L. M. Renjifo, A. M. Amaya-Villarreal, J. Burbano-Girón, and J. Velásquez-Tibatá, Editors). Editorial Pontificia Universidad Javeriana, and Instituto de investigación de Recursos Biológicos Alexander von Humboldt, Bogotá, Colombia.
    ** Renjifo, L. M., A. M. Amaya-Villarreal, J. Burbano-Girón, and J. Velásquez-Tibatá (Editors) (2016). Libro rojo de las aves de Colombia vol. II: especies acuáticas de ecosistemas abiertos y secos, tierras altas del Darién, Sierra Nevada de Santa Marta e insulares. Editorial Pontificia Universidad Javeriana, and Instituto de investigación de Recursos Biológicos Alexander von Humboldt, Bogotá, Colombia.

  2. 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

  3. Red List Team (BirdLife International) says:

    Preliminary proposal

    Based on available information, our preliminary proposal for the 2021 Red List would be to adopt the proposed classifications outlined in the initial forum discussion.

    Based on an area of habitat of 462 sqkm and using the density of 5-10 individuals/sqkm as a maximum density, the population is inferred to number up to 2,300-4,600 individuals, roughly equating to 1,500-2,300 mature individuals. To account for the species’s rarity, the population size is suspected to be smaller and therefore it is here placed in the band 1,000-3,000 mature individuals. Despite the potentially moderately small or small population size, the low level of data quality does not allow a listing as threatened.

    IUCN stipulates that the AOO be quantified at a scale of 4 sqkm, and as such the area of habitat from Renjifo et al., which has been quantified at a scale of 1 sqkm, cannot be used for the assessment of the AOO. In view of the species’s tolerance to some habitat degradation (Renjifo et al. 2016) and negligible habitat loss over the past ten years (Renjifo et al. 2016; Global Forest Watch 2021), locations cannot be used and the subcriterion referring to the number of locations is not met.

    There is now a period for further comments until the final deadline in late July, after which the recommended categorisations will be put forward to IUCN.

    The final 2021 Red List categories will be published on the BirdLife and IUCN websites in December 2021, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  4. Red List Team (BirdLife International) says:

    Recommended categorisation to be put forward to IUCN

    The final categorisation for this species has not changed. Santa Marta Warbler is recommended to be listed as Near Threatened, approaching the threshold for listing as threatened under Criterion D1.

    Many thanks for everyone who contributed to the 2021 GTB Forum process. The final 2021 Red List categories will be published on the BirdLife and IUCN websites in December 2021, following further checking of information relevant to the assessments by both BirdLife and IUCN.

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