Archived 2020 topic: Esmeraldas Woodstar (Chaetocercus berlepschi): revise global status?

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.

References

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.

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10 Responses to Archived 2020 topic: Esmeraldas Woodstar (Chaetocercus berlepschi): revise global status?

  1. Red List Team (BirdLife International) says:

    Global Forest Change data on tree cover loss up to 2019 have now been released and made available via Global Forest Watch. Based on these data, over ten years approximately 4.0% of tree cover with 75% canopy cover was lost from within the species’s range (Global Forest Watch 2020). This does not affect the above assessment under Criterion A.

  2. I disagree with moving Esmeraldas Woodstar to near-threatened. At the very least, it needs to be maintained as vulnerable under criterion C.

    There is a consensus that the population is below 10,000 mature individuals with an inferred population decline and subpopulations numbering below 1000 individuals. Given the disjoint breeding areas so far known for the species, the structuring of the population into sub-populations is logic corollary. With Ana Agreda’s population estimate of 1250-2750 mature individuals and at least 2, possibly 4 subpopulations, there is no evidence that any subpopulation numbers >1000 mature individuals.

  3. Dear reviewer,

    Esmeraldas Woodstar should not be down-listed to Near-threatened.

    Esmeraldas Woodstar occurs mainly along the coast of Manabí province, at Reserva Jama, Pacocha, Reserva Cantagallo, Rio Blanco (Machallila National Park), Reserva la Esmeralda, Reserva Ayampe, Reserva Loma Alta (per A. Agreda). Additionally, one individual was seen in 2017 in the Esmeraldas province close to the San Francisco-Galerito area during a bird survey (Fundación Jocotoco). Populations are fragmented in at least four-five subpopulations(1.Jama, 2. Pacoche, 3.Cantagallo-Ayampe, 4. Loma Alta, 5. San Francisco-Galerita), and no evidence shows that subpopulations exceed 250 mature individuals. In addition, a gap of information exists on the temporary migration of the species outside the breeding season. Few data exist on breeding locations after 2010. Nine nests were encountered at two localities (Ayampe, La Esmeralda) of the same subpopulation in 2020 (M. Moens, Fundación Jocotoco).

    The population size of mature individuals of Esmeraldas Woodstar does not likely exceed 2.500 and no subpopulation is estimated to be higher than 250 mature individuals. This is combined with severe ongoing habitat destruction in Western Ecuador, especially in coastal Ecuadorian dry forest (Portillo-Quintero and Sanchez-Azofeifa 2010). Esmeraldas Woodstar should be thus be assessed as EN under criterion C2ai.

    In addition, the updated Red List of Ecuadorian birds was published in 2019 , assessing all Ecuadorian species against IUCN criteria. The Esmeraldas Woodstar was classified as endangered under A2c+3c+4c; C2a(ii) (Freile et al. 2019).

    Freile, J. F., T. Santander G., L. Carrasco, D. F. Cisneros-Heredia, E. A. Guevara, M. Sánchez-Nivicela y B. A. Tinoco. (2019). Lista roja de las aves del Ecuador continental. Ministerio del Ambiente, Aves y Conservación, Comité Ecuatoriano de Registros Ornitológicos, Universidad del Azuay, Red Aves Ecuador y Universidad San Francisco de Quito. Quito, Ecuador.

    Portillo-Quintero CA, Sanchez-Azofeifa GA. 2010. Extent and conservation of tropical dry forests in the Americas. Biol Conserv. 143:144-55.

  4. Ana Agreda says:

    Esmeraldas Woodstar one of the tiniest hummingbird in the world, endemic to Ecuador, should be downlisted to Near-threatened global conservation status.

    Esmeraldas Woodstar distributional range extends from Northern Manabí province southwards to Loma Alta Ecological Reserve in Sta. Elena, the species has been not found in Guayas province ever. There are historical records of the species coming from Esmeraldas province but despite all the exploration I carried out between 2008-2009, I never recorded a single individual in Esmeraldas province. Recently, however, a male was recorded in Galeras by Francisco Sornoza during an exploration of Jocotoco Foundation. The fact that there was a male recorded does not indicate that there is for sure a breeding population in that new area.
    What we know for sure, is that the species breeds at four different areas, Jama Mountains in northern Manabi (Agreda unpub.), Pacoche forest (Agreda unpub), Machalilla National Park and its buffer zone (Juiña et al. 2010) and Loma Alta Ecological Reserve (Harris et al. 2009).

    Estimates of population size published by myself earlier were based on a predictive model of the distribution of Esmeraldas Woodstar produced with MAXENT v. 3.2.1. using as main criteria confirmed sightings of 28 adult reproductive males (including historical records). Based on this analysis we came up with a predictive range of 2500 – 5000 km2 (Agreda et al. unpub.). Calculations of population size used population estimates of 0.9 – 1.8 individuals per km2 (Birdlife International 2008) resulting in an estimate global population size of c. 2000 – 4000 individuals (Agreda et al. unpub.) However, this is the case of a low density species with a very restricted range and little population and ecological information so we should warrant a more conservative stance. Further, in the same publication when analyzing threats I mentioned the effects of human activity on C. berlepschi populations. Sierra et al. (1999) pointed out that the coastal evergreen pre-montane forest (0-450 m) and coastal montane fog forest (450-800 m) are endangered due to habitat destruction and deforestation. This elevation gradient is critical to the survival of this hummingbird species at least during the reproductive cycle.

    Indeed the discovery of several breeding populations in western Ecuador and the description of the female plumage has improved our knowledge of the status of the species, however it is important to notice that despite this information, nesting failures can be high especially considering that C. berlepschi uses narrow river beds that are prone to overflow, so breeding success has not been determined (see Juiña et al. 2010), neither reliable information on migratory movements, non-breeding distributional range and complete life cycle ecology. Resilience is an important aspect of species mentioned in Harris et al 2009 but nesting failure might be high and the species breeds on an annual basis.

    Regarding the text under Criterion A. According to the text the only threat known to the species is habitat loss and degradation, and forest loss has been low over the past ten years, however, another important threat is Climate change. This last 10 years have been dry, however during ENSO (El Niño) years forest destruction is high due to grow and overflow of all the coastal rivers, to the point that it is impossible to access the region. Rivers throughout the Coastal Cordillera Chongon Colonche are intermittent, they stay dry but during a very short but intense winter simply overflow. Climate change is a permanent threat to the species.

    Regarding Criterion B the extent of occurrence is not 28,500 km2, an estimated size of the area where the species has been recorded is not greater than 10,000 km2 at the most, this includes the evergreen premontane forest and fog forest in Manabí and Sta. Elena provinces, the species is not present in Guayas and there are not certain records of a population in Esmeraldas. We are talking at the most of four subpopulations where the numbers of reproductive adults do not reach the 1000 individuals. Thereby the species can not be downlisted to near threatened. It should stay as it is, as an endangered species.

  5. Ana Agreda says:

    The Esmeraldas Woodstar should not be downlisted to Near-threatened.

    The Esmeraldas Woodstar distributional range extends from northern Manabí province southwards to Loma Alta Ecological Reserve in Sta. Elena, the species has never been recorded in Guayas province. There are historical records of the species in Esmeraldas province but not currently. Despite exhaustive explorations carried out between 2008-2009, I never recorded the species in Esmeraldas province. However, more recently one individual of C. berlepschi was recorded in Galeras by Francisco Sornoza during an exploration of Jocotoco Foundation.

    The species breeds at four different areas, Jama Mountains in northern Manabi and Pacoche forest (Agreda 2008, 2009), Machalilla National Park and its buffer zone and Loma Alta Ecological Reserve (Agreda 2008, Harris et al. 2009, Juiña et al. 2010).

    Population size estimates published in Agreda 2020 were based on a predictive model of the distribution of Esmeraldas Woodstar produced with MAXENT v. 3.2.1. using as main criteria confirmed sightings of 28 adult reproductive males (including historical records). Based on this analysis we came up with a predictive range of 2500 – 5000 km2 (Agreda et al. unpub.). Calculations of population size used population estimates of 0.9 – 1.8 individuals per km2 (Birdlife International 2008) resulting in an estimate global population size of c. 2000 – 4000 individuals. However, C. berlepschi is a low density species with a very restricted range and little population and ecological information so we should warrant a more conservative stance. Further, Sierra et al. (1999) pointed out that the coastal evergreen pre-montane forest (0-450 m) and montane fog forest (450-800 m) are endangered due to habitat destruction and deforestation. This elevation gradient is critical to the survival of this hummingbird species at least during the reproductive cycle.

    The discovery of several breeding populations in western Ecuador in 2009 and the description of the female plumage has improved our knowledge of the status of the species, however nesting failures can be high especially considering that C. berlepschi uses narrow river beds that are prone to overflow (see Juiña et al. 2010). Critical information is still lacking such as reliable information on migratory movements, non-breeding distributional range and complete life cycle ecology. Resilience is an important aspect of the species ecology mentioned in Harris et al 2009, and it was also mentioned that the species uses secondary riparian habitat for breeding, however nesting failure might be high during heavy rainy season and the species breeds only on an annual basis.

    Regarding the text under Criterion A. According to the text the only threat known to the species is habitat loss and degradation, and forest loss has been low over the past ten years, however, another important threat is Climate change. Over the last 15 years the climate has been dry and cold due to La Niña, however during ENSO (El Niño) years forest destruction is high due to grow and overflow of all the coastal rivers, to the point that it is impossible to access the region. Rivers throughout the Coastal Cordillera Chongon Colonche are intermittent, they stay dry but during a very short but intense rainy season, the rivers simply overflow which puts the reproduction of the species at risk. Climate change and other natural events such as extreme rainfall are other important threats to the species.
    Regarding Criterion B the extent of occurrence is not 28,500 km2, based on our predictive model distribution we came up with an estimated predictive range of 2000-5000 km2, this includes the evergreen premontane forest and fog forest in Manabí and Sta. Elena provinces, the species is not present in Guayas and there are not certain records of a population in Esmeraldas.
    Based on our published records there are at the most four subpopulations of C. berlepschi along the coastal cordillera in western Ecuador, but no subpopulation is larger than 250 mature individuals. Although we are more capable nowadays to identify and detect the species, this hummingbird is still rare.

    Ágreda, A. 2008. Informe para Renovación de los permisos de Investigación del Proyecto “Conservación de la Estrellita de Esmeraldas (Chaetocercus berlepschi) en el occidente de Ecuador. Preparado para Ministerio del Ambiente de Ecuador

    Ágreda, A. 2009. Extensión de rango, ecología y conservación de la Estrellita de Esmeraldas (Chaetocercus berlepschi) en el occidente de Ecuador. In: J. F. Freile, D. F. Cisneros-Heredia, Agreda, A. E., Lara, A. and T. Santander (editors). Memorias II Reunión Ecuatoriana de Ornitología, 26-28 Agosto de 2009, Guayaquil. Quito, Ecuador: Aves & Conservación, Fundación Numashir, Universidad San Francisco de Quito.

    HARRIS, J. B., A. E. ÁGREDA, M. E. JUIÑA, AND B. P. FREYMANN. 2009. Distribution, plumage, and conservation status of the endemic Esmeraldas Woodstar (Chaetocercus berlepschi) of western Ecuador. Wilson Journal of Ornithology 121:227–239.

    JUIÑA, M. E., J. B. HARRIS, H. F. GREENEY, AND B. R. HICKMAN. 2010 Descripción del nido y cuidado parental de Chaetocercus berlepschi en el occidente de Ecuador. Ornitología Neotropical 21:313–322.

  6. Juan Freile says:

    Agreda’s figure of 2000-4000 ind is likely overestimating the potential population size of this species, and should be used with extreme caution, considering that the author provides no details on how this estimate was obtained. In our 2019 assessment for the Ecuador Red List, we obtained a different, albeit also rough estimate of 1000–3000 individuals (which totals 625–2060 mature individuals). There are less than five known subpopulations (Pacoche, Jama, and Machalilla-Ayampe-Loma Alta are the only properly known subpopulations). Other authors consider Ayampe and Loma Alta as separate subpopulations, but they are close geographically. If we consider that this species moves seasonally, then the entire Chongón Colonche mountain range might represent a single subpopulation. Anyhow, it is highly unlikely that subpopulations contain more than 250 mature individuals (criterion C for EN).
    In our 2019 assessment for the Ecuador Red List, we estimated a smaller EOO (roughly 15,000 km2). Even though it is not precise, I consider that your estimate of 28,000 km2 is overestimating the actual EOO.
    It is decidedly misleading to consider this woodstar as tolerant to degraded and converted habitats. It is regularly seen in forest edges and gardens not far from forests, but it is not a species of open habitats at all. As the species tends to move seasonally (or erratically?), it might be seen in fairly disturbed habitats, but that is more a consequence of observers bias towards more accessible, disturbed habitats. It needs to be pondered that intervening habitats between known subpopulations (i.e., areas between Chongón-Colonche and Pacoche, between Pacoche and Jama) are largely degraded and habitat loss is ongoing mainly due to agricultural expansion and urbanization. The species might perform seasonal/altitudinal movements to the wetter northwest Andean foothills and slopes, but the extreme degree of habitat disturbance in the intervening areas between the coastal mountains where it breeds and the Andean foothills might even halt this purported migration. As mentioned, it tolerates a certain level of habitat disturbance and readily occupies edge habitats, but it is not a species of urbanized areas or large agricultural fields, which abound and continue to expand in coastal Ecuador (the species avoids banana, balsa, cacao, oil palm, pineapple, rice, and any other sort of large monocultures that dominate the landscape in most of central Pacific Ecuador).
    Our 2019 estimate of potential population decline is higher and serves to rank this species as EN under A2+A3 considering its low tolerance to serious habitat disturbance; however, we admit that generation length is possibly too short to apply criterion A.
    Even if we assume that Agreda’s estimate is correct, then the species might be classified as VU under criterion C (there is no need to meet all three conditions to be listed under criterion C). It meets population size for both EN or VU under criterion C, and also meets projected decline (C1) and size of each subpopulation (C2ai). The species has not be classified as either EN or VU under criterion C. There is apparently a misinterpretation of requirements for applying criterion C.

  7. 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

  8. Red List Team (BirdLife International) says:

    Preliminary proposal

    Based on available information, our preliminary proposal for the 2020 Red List would be to list Esmeraldas Woodstar 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.

    Please note that we will then only post final recommended categorisations on forum discussions where these differ from the initial proposal.

    The final 2020 Red List categories will be published on the BirdLife and IUCN websites in December 2020/January 2021, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  9. Bert Harris says:

    I just now saw this but I am relieved to see that that this rare, localized, and still poorly known (e.g. non-breeding range) species has not been downlisted to NT.

  10. Red List Team (BirdLife International) says:

    Recommended categorisation to be put forward to IUCN

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

    Many thanks for everyone who contributed to the 2020 GTB Forum process. The final 2020 Red List categories will be published on the BirdLife and IUCN websites in December 2020/January 2021, following further checking of information relevant to the assessments by both BirdLife and IUCN.

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