BirdLife species factsheet for Esmeraldas Woodstar
Esmeraldas Woodstar (Chaetocercus berlepschi) is endemic to Ecuador, where it occurs along the coast from Esmeraldas in the north to Manabí, Santa Elena and Guayas in the south. It inhabits a variety of habitats, from semi-deciduous and evergreen moist forests to disturbed areas and gardens (Harris et al. 2009, Ágreda 2020). The population is estimated to number 2,000-4,000 individuals (Ágreda 2020), roughly equating to 1,250-2,750 mature individuals.
The species is threatened by the loss of its habitat. Large parts of the original vegetation in the lowlands of western Ecuador have already been converted for agricultural purposes (Dodson and Gentry 1991, Best et al. 1996). Habitat conversion is ongoing, at least in unprotected areas (Dodson and Gentry 1991). However, the species’s tolerance of disturbed habitat and its good dispersal abilities indicates some resilience to the loss and fragmentation of forests (B. Harris in litt. 2020).
Esmeraldas Woodstar is currently listed as Endangered under Criteria A2c+3c+4c; B1ab(i,ii,iii,v); C2a(ii) (BirdLife International 2020). However, a previous underestimate of the population size and new information regarding the population trend and distribution range suggests that the species may warrant a change in Red List status. Therefore, it will be re-assessed against all Red List criteria:
Criterion A – The population trend has not been estimated directly. The only threat known to the species is the loss and degradation of its habitat. Forest loss within the range has been low over the past ten years (<4%; Tracewski et al. 2016, Global Forest Watch 2020; one generation length being 2.0 years; Bird et al. 2020*). Given that the species does not depend on forest, but readily tolerates degraded and converted habitats, the rate of population decline is likely considerably lower than the rate of forest loss. However, using a very conservative approach, we can suspect that the combined effects of forest loss and degradation drive a population decline of up to 29% over ten years, and precautionarily list Esmeraldas Woodstar as Near Threatened, approaching the threshold for listing as threatened under Criterion A2c+3c+4c.
Criterion B – The Extent of Occurrence (EOO) for this species is 28,500 km2. This value does not meet the threshold for Vulnerable (EOO < 20,000 km2). The Area of Occupancy (AOO) has not been quantified according to the guidelines (IUCN Standards and Petitions Committee 2019). Therefore, Esmeraldas Woodstar may be listed as Least Concern under Criterion B1.
Criterion C – The population size of Esmeraldas Woodstar has been estimated at c. 1,250-2,750 mature individuals (Ágreda 2020). This meets the threshold for listing as threatened under Criterion C. However, to do so a species must meet further conditions.
It is suspected that the species is undergoing a slow population decline due to habitat loss. A suspected decline, however, precludes a listing as threatened under Criterion C. Even though we have no direct information on the subpopulation structure, we can tentatively assume that no subpopulation contains more than 1,000 mature individuals. Furthermore, it is suspected that the species is undergoing a decline of 30-49% over ten years, which would equate to a decline of 16-29% over five years. Overall, the species only meets two out of three conditions and can therefore not be listed as threatened under Criterion C. Nevertheless, it may be listed as Near Threatened, approaching the threshold for listing as threatened under Criterion C1+2a(i).
Criterion D – The population size is estimated at 1,250-2,750 mature individuals (Ágreda 2020). Assuming that the true population size is closer to the lower end of the estimate, this number approaches the threshold for listing as Vulnerable. Therefore, Esmeraldas Woodstar may be considered Near Threatened, approaching the threshold for listing as threatened under Criterion D1.
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 Esmeraldas Woodstar (Chaetocercus berlepschi) be listed as Near Threatened, approaching the threshold for listing as threatened under Criteria A2c+3c+4c; C1+2a(i); D1. 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).
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.
Ágreda, A. E. 2020. Esmeraldas Woodstar (Chaetocercus berlepschi), version 1.0. In: Schulenberg, T. (ed.) Birds of the World. Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.esmwoo2.01 (Accessed 05 March 2020).
Best, B. J.; Checker, M.; Thewlis, R. M.; Best, A. L.; Duckworth, W. 1996. New bird breeding data from southwestern Ecuador. Ornitologia Neotropical 7(1): 69-73.
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: Chaetocercus berlepschi. http://www.birdlife.org (Accessed 05 March 2020).
Dodson, C. H., and A. H. Gentry. 1991. Biological extinction in western Ecuador. Annals of the Missouri Botanical Garden 78: 273-295.
Global Forest Watch. 2020. Interactive Forest Change Mapping Tool. http://www.globalforestwatch.org (Accessed 18 February 2020).
Harris, J. B. C.; Ágreda, A. E.; Juiña, M. E.; Freymann, B. P. 2009. Distribution, plumage and conservation status of the endemic Esmeraldas Woodstar (Chaetocercus berlepschi) of western Ecuador. Wilson Journal of Ornithology 121(2): 227-239
IUCN Standards and Petitions Committee. 2019. Guidelines for using the IUCN Red List Categoreis and Criteria. Version 14. http://www.iucnredlist.org/documents/RedListGuidelines.pdf.
Tracewski, Ł.; Butchart, S. H. M.; Di Marco, M.; Ficetola, G. F.; Rondinini, C.; Symes, A.; Wheatley, H.; Beresford, A. E.; Buchanan, G. M. 2016. Toward quantification of the impact of 21st-century deforestation on the extinction risk of terrestrial vertebrates. Conservation Biology 30: 1070-1079.