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| 2010 IUCN Red List Category (as evaluated by BirdLife International - the official Red List Authority for birds for IUCN): Critically Endangered Justification This species is classified as Critically Endangered becase it has a tiny population. Numbers fluctuate owing to extreme weather, and in 2008 the population increased to be above the threshold for Critically Endangered. If the population remains at this level for more than five years, or if reintroduction efforts prove successful, the species may be downlisted in the future.
Family/Sub-family Mimidae Species name author (Gould, 1837) Taxonomic source(s) SACC (2005 + updates), Sibley and Monroe (1990, 1993), Stotz et al. (1996) Synonyms Nesomimus trifasciatus BirdLife International (2004) Taxonomic note The genus Nesomimus has been subsumed into the genus Mimus following SACC (2007).
Identification 25 cm. Largish, brown passerine. Dark brownish-grey upperparts. Whitish underparts with conspicuous dark patches on sides of breast. Long, graduated tail with pale tips. Longish, curved beak. Red-brown eyes. Voice Strident call. Long, melodious song. Does not mimic other birds. |  |
Population estimate | Population trend | Range estimate (breeding/resident) | Country endemic? | <50 | fluctuating | 2 km2 | Yes |
Range & population This species survives in low numbers on Champion (0.1 km2) and Gardner-by-Floreana (0.8 km2) islets in the Galápagos Islands, Ecuador3. It became extinct on the much larger Floreana (173 km2) between 1868 and 18881. In 1966, the population was estimated to be no more than 150 birds4. Between 1980 and 1991, annual counts showed that there were 8-12 (average 10) territories on Champion, with 24-53 birds in total3. On the same island between 2003 and 2007, numbers of birds varied from 20 to 52, but overall there was a downward population trend with 18 adults left in 20077. A similar trend was noted on Gardner-by-Floreana during the same period, with the number of birds on that island varying between 67 and 148, and the number of adults in 2007 falling to 307,11. The population recovered in 2008 due to good weather conditions and may have reached record numbers for the last decade, however such population highs are likely only to be temporary as the islands cannot support such numbers and the populations are still extremely prone to climate-induced fluctations13,14,15. A population viability analysis of the Champion population suggested that there is less than a 50% chance of the bird persisting on the island for another 100 years.
| Important Bird Areas Click here to view map showing IBAs where species is recorded and triggers any of the IBA criteria. | Ecology: It inhabits the large cactus Opuntia megasperma and other stands of vegetation, including Parkinsonia, Croton and Cordia1. It feeds mostly on terrestrial insects, but also takes arboreal insects, fruit, nectar, pollen, centipedes, crabs, lizards and regurgitated food of boobies Sula spp.2. It is a co-operative breeder, with a variable mating system2.
| Threats Extinction on Floreana was probably caused by the introduction of black rat Rattus rattus1. Higher adult mortality occurs in the unusually dry La Niña years3; dry years are increasing in frequency, and this is thought to be driving fluctuations in the population size (as seen in 2007 and 2008) which leave the species prone to extinction14. The Smooth-billed Ani Crotophaga ani is known to predate other bird species on the archipelago and has been seen on Champion and Gardner-by-Floreana8. Increased mortality on Champion during the 1982-1983 El Niño event is thought to have been the result of avian pox virus3, and the invasive parasite Philornis downsi has been recorded12. There are black rats present on nearby islets whose accidental introduction to either of the breeding islands poses an ever present threat8. The loss of immigration from the now extinct Floreana population has raised concerns for the long-term survival of the two remaining populations, as they are believed to have lost a significant amount of genetic diversity3.
| | Conservation measures underway A ten-year action plan was developed in 2007, with plans to take active measures to safeguard existing populations, and to create suitable conditions for reintroduction to Floreana7,8,9. The Reintroduction Plan is supported by an Emergency Plan (to enable rapid response to critical downward population trends)10, the Introduced Rodent Eradication Program initiated in 2007 and the initiation of Project Floreana, aimed at the restoration of the island9. The Galápagos National Park was gazetted in 1959, and includes almost all the land area of the islands. In 1979, the islands were declared a World Heritage Site5. The Charles Darwin Foundation is plans to re-introduce the species to Floreana, however no translocation will occur in 2010 as an el Niño event is expected which would make rat control on the island very difficult16.
| | Conservation measures proposed Monitor populations and environmental conditions on both islands, preferably annually3. Eradicate the Smooth-billed Ani from the two islets. Minimise chance introductions of predators and disease. Reintroduce to Floreana if eradication of rats, pigs, goats and donkeys is successful. Investigate possibility of reintroduction to other islets where black rat is absent.
| References Collar et al. (1992). 1. Curry (1986). 2. Curry and Grant (1991). 3. Grant et al. (2000). 4. Harris (1968). 5. Jackson (1985). 6. Charles Darwin Foundation (2007a). 7. Charles Darwin Foundation (2007b). 8. G. Jimenez-Uzcategui in litt. (2007). 9. Anon (2008). 10. Anon (2008b). 11. Jiménez-Uzcátegui (2007). 12. Wiedenfeld & Jiménez-Uzcátegui (2008). 13. Hoeck (2009). 14. D. Wiedenfeld in litt. (2010). 15. Charles Darwin Foundation in litt. (2009). 16. P. Hoeck in litt. (2010).
| Text account compilers Rob Calvert (BirdLife International), James Gilroy (BirdLife International), Isabel Isherwood (BirdLife International), Simon Mahood (BirdLife International), Rachel McClellan (BirdLife International), Rob Pople (BirdLife International - European Division), Andy Symes (BirdLife International) | Contributors T de Vries (Pontificia Universidad Católica del Ecuador), Paquita Hoeck (University of Zürich), Gustavo Jimenez-Uzcategui, Alan Tye, David Wiedenfeld (American Bird Conservancy) | IUCN Red List evaluators Stuart Butchart (BirdLife International), Rob Calvert (BirdLife International), Andy Symes (BirdLife International) |
| Recommended citation BirdLife International (2010) Species factsheet: Mimus trifasciatus. Downloaded from http://www.birdlife.org on 3/9/2010 | This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List. To provide new information to update this factsheet or to correct any errors, please email BirdLife To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums |
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