CR
Chilean Woodstar Eulidia yarrellii



Justification

Justification of Red List Category
This species is classified as Critically Endangered based on evidence that it has undergone an extremely rapid population decline. Urgent research and targeted conservation actions are now required to understand, halt and reverse this decline.

Population justification
Recent counts from 2010-2015 have produced estimates of between 405 and 592 individuals (Lazzoni Traversaro 2015, Yañez 2016), which roughly equates to 270 - 395 mature individuals.

Trend justification
Evidence from surveys and anecdotal observations indicates that this species has undergone an extremely rapid decline. Population estimates have shown that the Azapa and Chaca populations have reduced by 15.6% annually (81.6%) in 10 years (C. F. Estades in litt. 2013). Although the rate of decline appears to have lessened over recent years, population counts from between 2003 and 2015 (Lazzoni Traversaro 2015, Yañez 2016) indicate that the population has likely undergone a reduction of approximately 80% across the past three generation lengths.

Distribution and population

Eulidia yarrellii is only known to breed regularly in the Azapa, Chaca (Vitor) and Camarones valleys, Arica department, extreme northern Chile (Estades 2007, A. Jaramillo in litt. 2014). Stragglers have been found north to Tacna and possibly Moquegua departments, southern Peru, and there is a historical record as far south as northern Antofagasta province; yet, there are no recent records for Peru (Estades 2007). It was described as very common in the first half of the 20th century, with over 100 individuals seen feeding together. In the late 1980s, the species was noted as common in gardens in Arica and regular in the Lluta Valley; however, it has since disappeared from these areas, and it is now rare in the Azapa Valley, where it was once regular and common (Estades 2007, A. Jaramillo in litt. 2014). In 2003, the Azapa valley held around 75% of the total population, which was estimated at around 1,500 individuals (Estades 2007), while in 2007 the total population was estimated at around 1,200 individuals (55% in Azapa and 45% in Chaca) (C. F. Estades in litt. 2007). Recent counts from 2010-2015, however, suggests that the population has since declined to around 500 individuals (D. Lebbin in litt. 2012, Lazzoni Traversaro 2015, Yañez 2016). Population estimates have shown that the Azapa and Chaca populations have reduced by 15.6% annually (81.6%) in 10 years (C. F. Estades in litt. 2013). Although the rate of decline appears to have lessened over recent years, population counts from between 2003 and 2015 (Lazzoni Traversaro 2015, Yañez 2016) indicate that the population has likely undergone a reduction of approximately 80% across the past three generation lengths. Monthly searches for the species in all Tacna valleys (southern Peru) during 2008-2009 did not yield any records of this species (N. Hidalgo in litt. 2013). It has been speculated that the species could be lost from the Azapa Valley within a decade, and that the species could face extinction within two decades (A. Jaramillo in litt. 2014).

Ecology

The species inhabits small remnant patches of native scrub in desert river valleys up to 750 m, but birds are occasionally reported above 2,000 m and once as high as 3,000 m (J. Fjeldså in litt. 1999, Estades 2007). It migrates altitudinally and may require fairly continuous vegetation along rivers to undertake such movements (Howell and Webb 1995). Estades et al. (2007) observed woodstars feeding on the flowers of native trees like the chañar (Geoffroea decorticans) and pimiento (Schinus molle), as well as ornamentals like Lantana camara, Pelargonium spp. and Bougainvillea sp. and crop plants such as alfalfa (Medicago sativa), garlic, onion (Allium spp.), and tomato (Lycopersicon esculentum). They noted that the favoured species have entomophyllous flowers rather than typical ornithophyllous flowers (Estades et al. 2007). The species has often been reported feeding in gardens, particularly on Lantana and Hibiscus flowers (Fjeldså and Krabbe 1990), but it is comparatively rare in such habitats (Howell and Webb 1995). It uses fruit groves for feeding (Citrus spp.) and nesting (olive trees) (C. Estades in litt. 2007). Despite the large numbers formerly seen feeding in flowering trees, it is usually a solitary feeder. Active nests have been found in April, May, late August and September and there appear to be two annual peaks in breeding activity (Estades 2007, Estades et al. 2007). It is likely that males display at leks. Courtship territories are placed above dense thickets which are now scarce in Azapa and Vítor (Clark et al. 2013).

Threats

Remaining native habitat in the narrow and heavily cultivated valleys inhabited by the species is confined to small patches, and the indigenous plants favoured may be severely threatened. Dense thickets, possibly used as courtship territories, are now scarce due to the spread of agricultural activities in Azapa and Vítor (Clark et al. 2013). Although it has adapted to use introduced plants, the presence of certain native species may still be a limiting factor (Estades 2007). The chañar tree Geoffroea decorticans may be an important food resource, but is often destroyed by farmers who consider it invasive and believe it attracts mice (Estades 2007). Pesticides began to be heavily used in the Azapa valley in the 1960s in order to control the Mediterranean Fruit-fly and other crop pests, but as the Peruvian Sheartail Thaumastura cora has not suffered similar declines, this may not be the primary cause of this species's decline (Estades 2007). Competition with Peruvian Sheartail has been suggested as a potential threat (Estades et al. 2007, C. Estades in litt. 2007, S. N. G. Howell in litt. 2007, Clark et al. 2013). A recent study which examined interactions between the two species found that food niche overlap is relatively low and that E. yarrellii dominates T. cora in male–male territorial interactions. However, potentially increased energetic costs for E. yarrellii associated with frequent territorial chases and courtship displaying with sheartails may exacerbate the effects of other threats on E. yarrellii (van Dongen et al. 2013). Hybridisation is also a potential threat; a male hybrid of the two species was found in the Azapa valley where Peruvian Sheartail is common and Chilean Woodstar rare, and a low level of hybridisation has been found among the two species (Clark et al. 2013, van Dongen et. al. 2013). The various threats of habitat destruction, pesticide use and competition with other hummingbirds are likely to be synergistic in their impacts on the species (P. L. Gonzalez-Gomez in litt. 2014).

Conservation actions

Conservation Actions Underway
CITES Appendix II. All exports of hummingbirds from Peru and Chile are controlled. A ten-year species recovery plan was approved in 2004 and included plans for a public awareness campaign, a study of competition between the woodstar and Peruvian Sheartail, a permanent population monitoring programme, restoration of natural vegetation in the Azapa and Lluta valleys, incorporation of its conservation into the agenda of the local Good Agricultural Practices committee, and a study of the feasibility of an ex-situ conservation project and reintroduction into suitable areas within the historical range (Estades 2007, Estades et al. 2007). Attempts have been made to provide artificial feeders for the species; however, it proved reluctant to use them and other hummingbird species displaced E. yarrellii through their monopolisation of the new resource (P. L. Gonzalez-Gomez in litt. 2014). There are plans to create a network of small reserves to protect the habitat used by the species for lekking and breeding; two small reserves have now been created: the Chaca Biologic Station in the Valley of Vitor and El Rapido Biologic Station in the Azapa Valley (Lebbin 2013, Yañez 2016, Almendras undated). Trial habitat restoration at a site in the Chaca valley was successful, with the species using the restored habitat for breeding (Yañez 2016). Some work has been undertaken to raise awareness of the species's conservation among the public, particularly in schools (Yañez 2016).

Conservation Actions Proposed

Research the genetic structure of the populations. Carry out habitat restoration in the Lluta, Chaca and Azapa valleys, ensuring that species whose flowers are visited regularly by E. yarrellii are planted (P. L. Gonzalez-Gomez in litt. 2014). Continue population monitoring, as detailed in the species recovery plan. Limit the amount of pesticides used in Azapa and Chaca valleys. Investigate the effects of territorial interactions between Chilean Woodstar and Peruvian Sheartail (Clark et al. 2013). Scale-up work to raise awareness of the species among the general public (Yañez 2016). Continue with the planning of a network of small reserves to protect the habitat used by the species.

Identification

8 cm. Small hummingbird with short black bill. Iridescent olive-green upperparts. Male has violet-red throat. Rest of underparts white. Strongly forked tail. Short, green central rectrices. Longer outer rectrices blackish. Female white tinged buff below, tail unforked, and rectrices tipped white. Voice Song short, relatively simple high-pitched trill (Clark et al. 2013).

Acknowledgements

Text account compilers
Sharpe, C.J., Ashpole, J, Symes, A., Capper, D., Benstead, P., Taylor, J., Wheatley, H.

Contributors
Howell, S., Gonzalez-Gomez, P. L., Jaramillo, A., Fjeldså, J., Lebbin, D., Estades, C.


Recommended citation
BirdLife International (2020) Species factsheet: Eulidia yarrellii. Downloaded from http://www.birdlife.org on 30/09/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 30/09/2020.