Atlantic Woodcreeper (Xiphorhynchus atlanticus): Revise global status?

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5 Responses to Atlantic Woodcreeper (Xiphorhynchus atlanticus): Revise global status?

  1. Diego Mendes Lima says:

    In the assessment of the risk of extinction of the Brazilian fauna carried out in 2019, the species was categorized as Vulnerable (VU) by criterion C2a(i).

    Evaluators: Caio Graco Machado Santos, Diego Mendes Lima, Ciro Ginez Albano, Glayson Ariel Bencke, José Fernando Pacheco, Luís Fábio Silveira, Vítor de Queiroz Piacentini and Wagner Nogueira Alves.

    Criterion A – in the 2019 assessment, we did not find long-term population estimates data to track the decline by observed data (a) and the decline in AOO and EOO (c) do not reach the thresholds for a threat category. Habitat loss calculations performed with tools available on MapBioma (https://mapbiomas.org/) in the generational time of the species does not reach the population reduction threshold due to habitat loss in its range.

    Criterion B – The calculations of AOO (2,144 km2) with inferred and suspected records and EOO (167,142 km2) do not meet the thresholds for categorizing as threatened.

    Criterion C – Considered common in Serra de Baturité, Ceará, where 43.7 and 62.5 individuals/100 hours of observation were recorded in two different locations (Albano & Girão, 2008). Of 15 fragments studied in Alagoas, it was found in only two (Aleixo, 2008). CEMAVE/ICMBio has developed systematic studies aimed at obtaining data to estimate population density in several forest remnants in the State of Paraíba. In the Guaribas Biological Reserve, between 2018 and 2019, the population density of X. atlanticus was 0.14 individuals/ha. Considering only the area of ​​rainforest existing in the Rebio Guaribas of 3,200 ha, 448 individuals can be estimated for the area (Diego Mendes, pers. comm., 2019). Habitat fragmentation can isolate populations, as the species has little mobility outside the forest matrix, resulting in continued population decline due to habitat loss. Based on the population estimate data presented in the Rebio Guaribas, we can infer that within the species’ area of ​​occurrence the population is 6,500-9,999 mature individuals, and that its subpopulations have less than 1,000 mature individuals.

    Criterion D – the population size was estimated at 6,500-9,999 mature individuals and does not meet the thresholds for categorizing as threatened and its AOO is greater than 20 km2.

    Criterion E – in the assessment carried out in 2019, we did not find PVA data.

    JUSTIFICATION: Xiphorhynchus atlanticus is endemic to Brazil, with occurrence restricted to the northeast of the country (Ceará, Paraíba, Pernambuco and Alagoas). Considering that its distribution area is very well sampled and using population estimates data obtained from the Guaribas Biological Reserve, it is safe to infer that there are less than 10,000 mature individuals and that each subpopulation contains less than 1,000 individuals. Habitat fragmentation isolates populations, as the species has little mobility outside the forest matrix, resulting in continued population decline due to the loss of occupied area and habitat quality. Therefore, X. atlanticus was categorized as Vulnerable (VU) by the C2a(i) criterion.

  2. Ben Phalan says:

    In cases of single-country endemics like this where there is substantial uncertainty within the estimates of population size and other parameters, I would urge BirdLife to consider adopting the status from national red list assessments pending a more complete evaluation. I recognise that the sticking point in this case is that the population size is “suspected” rather than “estimated” (although perhaps there was more information used in a calculation that did not appear in the National Red List report?), but nevertheless, the suspected value from the national assessment is the best assessment available at this time, and is based on input from experienced ornithologists who know the species and the state of its remaining habitat better than anyone else.

    It would also be useful to know the population densities used here in the proposal (for X. fuscus and the median density of congeners) and how closely these match with the estimate cited by Diego Mendes Lima of 0.14 individuals/ha. The information from Diego suggests that the best estimate of habitat occupancy would be 13% (2 of 15 fragments surveyed in Alagoas). I’d suggest at least to recalculate the population size considering these density and occupancy values.

    Pending that estimate, my suggestion would be to uplist the species to Vulnerable, consistent with the National Red List assessment, but keep discussion on the forum open until a more precise estimate of the relevant parameters is available. I’m willing to help with a more systematic evaluation, if needed.

  3. 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

  4. Red List Team (BirdLife International) says:

    Preliminary proposal

    Following recalculation of the species’s population size using the new density estimate provided by Diego Mendes Lima, our preliminary proposal for the 2021 Red List would be to list Atlantic Woodcreeper as Vulnerable under Criterion C2a(i).

    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.

    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.

  5. Red List Team (BirdLife International) says:

    Recommended categorisation to be put forward to IUCN

    The final categorisation for this species has not changed. Atlantic Woodcreeper is recommended to be listed as Vulnerable under Criterion C2a(i).

    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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