Bahama Nuthatch (Sitta insularis): revise global status?

BirdLife species factsheet for Bahama Nuthatch

Bahama Nuthatch (Sitta insularis) is endemic to the Bahamas, where it is found only on one island, Grand Bahama Island (del Hoyo et al. 2018). It is a forest species with a very small range and population and is considered to be in decline due to habitat loss and degradation through logging and development, fires, hurricanes and possibly invasive species (Hayes et al. 2004). As a result of its small and declining population, it is currently listed as Endangered under Criterion C2a(ii) (BirdLife International 2018).

According to our current information, the Bahama Nuthatch has not been seen since June 2016 (B. Harris in litt. 2018). In September 2016, Grand Bahama was hit by Category five Hurricane Matthew, which caused damage to vegetation (Bahamas National Trust 2016). Recently, four days of intensive surveys for the Bahama Nuthatch, covering all sites where the species has been recorded in recent years, failed to find any individuals (B. Harris in litt. 2018). Furthermore, once per month for a year, a local bird guide visited one of the main sites where the species was previously recorded, without recording any individuals (B. Harris in litt. 2018). This lack of sightings suggests that the population size of Bahama Nuthatch may now be extremely small or even that the species could now be extinct.

We are therefore requesting information on the population size, trends and threats of the Bahama Nuthatch since the 2000s.

Our current information on the species’s conservation status will now be compared to all Red List Criteria.

Criterion A – Based on the lack of recent records, the species appears to have undergone a substantial population reduction, but we do not currently have evidence to allow a quantitative assessment of the magnitude of reduction, therefore the species cannot clearly be assessed under this criterion.

Criterion B – The species’s extent of occurrence (EOO) has been estimated as 80 km2, which meets the threshold for listing as Critically Endangered under Criterion B, and may now be even smaller. To be listed as threatened under Criterion B, two of three conditions must also be met. The species is likely to be declining due to habitat loss and invasive species. The number of locations (according to the IUCN definition*) has not currently been quantified and is dependent on the most serious plausible threat faced by the species; if the main threat is invasive species or hurricanes then the species likely only has one location; if the main threat is habitat loss then there may be more. If the species has between two and five locations then the species may qualify as Endangered under Criterion B1. If the species has only one location then the species may qualify as Critically Endangered under Criterion B1.

Criterion C – The species’s population size was estimated as 1,200 mature individuals in 2004 (Hayes et al. 2004), but the lack of recent records suggests that the population, if it remains at all, could now be extremely small. If evidence suggests that the population is smaller than 250 mature individuals, and is continuing to decline, then the species could be uplisted to Critically Endangered under Criterion C2a(ii).

Criterion D – If evidence suggests that the species’s population size is less than 50 mature individuals then it may qualify as Critically Endangered under Criterion D. If the population is better estimated at more than 50 mature individuals but fewer than 250, the species may qualify as Endangered under Criterion D.

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

To get a clearer assessment of the species’s status, information is requested on the population size, trends and threats of the Bahama Nuthatch since the 2000s.

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.

* “The term ‘location’ defines a geographically or ecologically distinct area in which a single threatening event can rapidly affect all individuals of the taxon present. The size of the location depends on the area covered by the threatening event and may include part of one or many subpopulations. 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).

References

Bahamas National Trust (2016) Hurricane Matthew. Trust Notes 10 (24): 1-2.

BirdLife International (2018) Species factsheet: Sitta insularis. Downloaded from http://www.birdlife.org on 15/02/2018.

del Hoyo, J., Collar, N. & Sharpe, C.J. (2018). Bahama Nuthatch (Sitta insularis). 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. (retrieved from https://www.hbw.com/node/1343988 on 19 February 2018).

Hayes, W. K., Barry, R. X., McKenzie, Z. and Barry, P. (2004) Grand Bahama’s brown-headed nuthatch: a distinct and endangered species. Bahamas Journal of Science 12: 21-28.

IUCN (2001) IUCN Red List Categories and Criteria: Version 3.1. Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, UK.

IUCN (2012) IUCN Red List Categories and Criteria: Version 3.1. Second Edition. IUCN, Gland, Switzerland and Cambridge, UK.

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4 Responses to Bahama Nuthatch (Sitta insularis): revise global status?

  1. Daniel Lebbin says:

    American Bird Conservancy is working with Bert Harris, Zeko McKenzie, Bahamas National Trust and others right now to conduct emergency field surveys on Grand Bahama in an effort to relocate any surviving Bahama Nuthatch populations. There is no evidence the population exceeds 250 individuals under Criteria C and therefore the species should be considered Critically Endangered. If no birds are found or no evidence of surviving birds is obtained during this search, Critically Endangered (Possibly Extinct) would be a more appropriate status and we can update BirdLife as to our findings after the study is completed (possibly before the June 30 forum deadline, but no guarantees there).

  2. Daniel Lebbin says:

    I will also add that there is no evidence the population exceeds 50 mature individuals under Criteria D, leading to the same Critically Endangered status.

  3. Hannah Wheatley (BirdLife) says:

    Preliminary proposal

    Based on available information, our preliminary proposal for the 2018 Red List would be to list this species as Critically Endangered under Criteria B1ab(iii,v); C2a(ii); D.

    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 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.

  4. Hannah Wheatley (BirdLife) says:

    Recommended categorisation to be put forward to IUCN

    Following further review, the recommended criteria string for Bahama Nuthatch has been revised. The species is still proposed to be listed as Critically Endangered, but now under Criteria A2a; B1ab(iii,v); C2a(i,ii); D.

    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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