Mimus trifasciatus

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	AVES	PASSERIFORMES	MIMIDAE

Scientific Name:

Mimus trifasciatus

Species Authority:

(Gould, 1837)

Common Name/s:

English

–

Charles Mockingbird, Floreana Mockingbird

Taxonomic Notes:

The genus Nesomimus has been subsumed into the genus Mimus following SACC (2007).

Assessment Information [top]

Red List Category & Criteria:

Critically Endangered D ver 3.1

Year Published:

2012

Assessor/s:

BirdLife International

Reviewer/s:

Butchart, S. & Symes, A.

Contributor/s:

de Vries, T., Hoeck, P., Jiménez-Uzcátegui, G., Tye, A. & Wiedenfeld, D.

Justification:
This species is classified as Critically Endangered because it has a tiny population. Numbers fluctuate owing to extreme weather, and in 2008 the population increased to be above the Critically Endangered threshold. 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.

History:

2010	–	Critically Endangered
2009	–	Critically Endangered
2008	–	Critically Endangered
2004	–	Endangered
2000	–	Endangered
1996	–	Endangered
1994	–	Endangered

Geographic Range [top]

Range Description:	This species survives in low numbers on Champion (0.1 km²) and Gardner-by-Floreana (0.8 km²) islets in the Galápagos Islands, Ecuador (Grant et al. 2000). It became extinct on the much larger Floreana (173 km²) between 1868 and 1880 (Curry 1986, Steadman 1986). In 1966, the population was estimated to be no more than 150 birds (Harris 1968). Between 1980 and 1991, annual counts showed that there were 8-12 (average 10) territories on Champion, with 24-53 birds in total (Grant et al. 2000). On the same island between 2003 and 2008, numbers of birds varied from 20-52, but overall there was a downward population trend with 12 adults left in 2006 (Charles Darwin Foundation 2007b, Jiménez-Uzcátegui et al. 2011). A similar trend was noted on Gardner-by-Floreana during the same period, with the number of birds on that island varying between 65 and 179, and the number of adults in 2007 falling to 29 (Charles Darwin Foundation 2007b, Jiménez-Uzcátegui 2007, Jiménez-Uzcátegui et al. 2011). 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 fluctuations (Hoeck 2009, Charles Darwin Foundation in litt. 2009, D. Wiedenfeld in litt. 2010). 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.
Countries:	Native: Ecuador (Galápagos)
Range Map:	Click here to open the map viewer and explore range.

Population [top]

Population:	Between 2003 and 2008, the population on Champion Island numbered 20-52 indviduals, with 65-179 on Gardner-by-Floreana. Both populations reached lows in 2007 following very bad weather conditions in 2006, with a total population of just 46 mature individuals remaining. Numbers then recovered in 2008 due to good, wet weather conditions (D. Wiedenfeld in litt. 2010). However, given that the population fluctuates, a population band of fewer than 50 individuals and mature individuals is precautionarily retained.
Population Trend:	Stable

Population:

Between 2003 and 2008, the population on Champion Island numbered 20-52 indviduals, with 65-179 on Gardner-by-Floreana. Both populations reached lows in 2007 following very bad weather conditions in 2006, with a total population of just 46 mature individuals remaining. Numbers then recovered in 2008 due to good, wet weather conditions (D. Wiedenfeld in litt. 2010). However, given that the population fluctuates, a population band of fewer than 50 individuals and mature individuals is precautionarily retained.

Population Trend:

Stable

Habitat and Ecology [top]

Habitat and Ecology:	It inhabits the large cactus Opuntia megasperma and other stands of vegetation, including Parkinsonia, Croton and Cordia (Curry 1986). It feeds mostly on terrestrial insects, but also takes arboreal insects, fruit, nectar, pollen, centipedes, crabs, lizards and regurgitated food of boobies Sula spp. It is a cooperative breeder, with a variable mating system (Curry and Grant 1991).
Systems:	Terrestrial

Threats [top]

Major Threat(s):	Extinction on Floreana was probably caused by the depredations of introduced black rats Rattus rattus, feral cats and feral dogs, with introduced goats causing habitat loss (Harris 1973, Curry 1986, Grant et al. 2000). Higher adult mortality occurs in the unusually dry La Niña years (Grant et al. 2000); 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 extinction (D. Wiedenfeld in litt. 2010). 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-Floreana (G. Jiménez-Uzcátegui in litt. 2007). Increased mortality on Champion during the 1982-1983 El Niño event is thought to have been the result of avian pox virus (Grant et al. 2000), and the invasive parasite Philornis downsi has been recorded (Wiedenfeld and Jimenez-Uzcategui 2008). There are black rats present on nearby islets whose accidental introduction to either of the breeding islands poses an ever present threat (G. Jiménez-Uzcátegui in litt. 2007). 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 diversity (Grant et al. 2000, Hoeck et al. 2009).

Major Threat(s):

Extinction on Floreana was probably caused by the depredations of introduced black rats Rattus rattus, feral cats and feral dogs, with introduced goats causing habitat loss (Harris 1973, Curry 1986, Grant et al. 2000). Higher adult mortality occurs in the unusually dry La Niña years (Grant et al. 2000); 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 extinction (D. Wiedenfeld in litt. 2010). 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-Floreana (G. Jiménez-Uzcátegui in litt. 2007). Increased mortality on Champion during the 1982-1983 El Niño event is thought to have been the result of avian pox virus (Grant et al. 2000), and the invasive parasite Philornis downsi has been recorded (Wiedenfeld and Jimenez-Uzcategui 2008). There are black rats present on nearby islets whose accidental introduction to either of the breeding islands poses an ever present threat (G. Jiménez-Uzcátegui in litt. 2007). 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 diversity (Grant et al. 2000, Hoeck et al. 2009).

Conservation Actions [top]

Conservation Actions:	Conservation Actions Underway A 10-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 Floreana (Charles Darwin Foundation 2007b, G. Jiménez-Uzcátegui in litt. 2007, Anon. 2008a). A ringing study is on-going to determine survival rates of the species; another study aims to assess the impacts of the parasite Philornis downsi on the mockingbird population (Ortis-Catedral 2012). The reintroduction plan is supported by an emergency plan, to enable rapid response to critical downward population trends (Anon. 2008b), the Introduced Rodent Eradication Program initiated in 2007 and the initiation of Project Floreana, aimed at the restoration of the island (Anon. 2008a). 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 Site (Jackson 1985). The Charles Darwin Foundation is plans to reintroduce the species to Floreana, however no translocation occurred in 2010 as an El Niño event was expected which would have made rat and cat control on the island very difficult (P. Hoeck in litt. 2010, G. Jiménez-Uzcátegui in litt. 2012). Conservation Actions Proposed Monitor populations and environmental conditions on both islands, preferably annually (Grant et al. 2000). Minimise the risk of chance introductions of predators and disease. Reintroduce to Floreana if eradication of rats, cats, anis, pigs, goats and donkeys is successful. Investigate possibility of reintroduction to other islets, or areas of Floreana, where black rats and cats are absent (G. Jiménez-Uzcátegui in litt. 2012).

Conservation Actions:

Conservation Actions Underway
A 10-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 Floreana (Charles Darwin Foundation 2007b, G. Jiménez-Uzcátegui in litt. 2007, Anon. 2008a). A ringing study is on-going to determine survival rates of the species; another study aims to assess the impacts of the parasite Philornis downsi on the mockingbird population (Ortis-Catedral 2012). The reintroduction plan is supported by an emergency plan, to enable rapid response to critical downward population trends (Anon. 2008b), the Introduced Rodent Eradication Program initiated in 2007 and the initiation of Project Floreana, aimed at the restoration of the island (Anon. 2008a). 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 Site (Jackson 1985). The Charles Darwin Foundation is plans to reintroduce the species to Floreana, however no translocation occurred in 2010 as an El Niño event was expected which would have made rat and cat control on the island very difficult (P. Hoeck in litt. 2010, G. Jiménez-Uzcátegui in litt. 2012).

Conservation Actions Proposed
Monitor populations and environmental conditions on both islands, preferably annually (Grant et al. 2000). Minimise the risk of chance introductions of predators and disease. Reintroduce to Floreana if eradication of rats, cats, anis, pigs, goats and donkeys is successful. Investigate possibility of reintroduction to other islets, or areas of Floreana, where black rats and cats are absent (G. Jiménez-Uzcátegui in litt. 2012).

Citation:	BirdLife International 2012. Mimus trifasciatus. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 24 May 2013.
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