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

Assessment Information [top]

Red List Category & Criteria:

Critically Endangered D ver 3.1

Year Published:

2010

Assessor/s:

BirdLife International

Reviewer/s:

Calvert, R., Symes, A., Butchart, S.

Contributor/s:

Wiedenfeld, D., Hoeck, P., Tye, A., de Vries, T., Jimenez-Uzcategui, G.

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.

History:

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, 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 30^7,11. 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 fluctations^13,14,15. 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.
Countries:	Native: Ecuador
Range Map:	Click here to open the map viewer and explore range.

Population [top]

Population:	Between 2003 and 2007, the population on Champion Island numbered 20-52 indviduals, with 67-148 on Gardner-by-Floreana. Both populations reached lows in 2007 following very bad weather conditions in 2006, with a total population of just 48 mature individuals remaining (Charles Darwin Foundation 2007b; Jiménez-Uzcátegui 2007). Numbers then recovered in 2008 due to good, wet weather conditions (D. Wiedenfeld in litt. 2010), and the population may have reached as many as 400 individuals on Gardner-by-Floreana (Hoeck, 2009). However, given the population fluctuates, a population band of <50 individuals is precautionarily retained.
Population Trend:	Unknown

Population:

Between 2003 and 2007, the population on Champion Island numbered 20-52 indviduals, with 67-148 on Gardner-by-Floreana. Both populations reached lows in 2007 following very bad weather conditions in 2006, with a total population of just 48 mature individuals remaining (Charles Darwin Foundation 2007b; Jiménez-Uzcátegui 2007). Numbers then recovered in 2008 due to good, wet weather conditions (D. Wiedenfeld in litt. 2010), and the population may have reached as many as 400 individuals on Gardner-by-Floreana (Hoeck, 2009). However, given the population fluctuates, a population band of <50 individuals is precautionarily retained.

Population Trend:

Unknown

Habitat and Ecology [top]

Habitat and 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.
Systems:	Terrestrial

Threats [top]

Major Threat(s):	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 diversity^3,17.

Major Threat(s):

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 diversity^3,17.

Conservation Actions [top]

Conservation Actions:	Conservation Actions 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 Floreana^7,8,9. 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 occurred in 2010 as an el Niño event was expected which would have made rat control on the island very difficult¹⁶. Conservation Actions Proposed Monitor populations and environmental conditions on both islands, preferably annually³. Eradicate the Smooth-billed Ani from the two islets. Minimise the risk of 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.

Conservation Actions:

Conservation Actions 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 Floreana^7,8,9. 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 occurred in 2010 as an el Niño event was expected which would have made rat control on the island very difficult¹⁶.

Conservation Actions Proposed
Monitor populations and environmental conditions on both islands, preferably annually³. Eradicate the Smooth-billed Ani from the two islets. Minimise the risk of 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.

Citation:	BirdLife International 2010. Mimus trifasciatus. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 24 May 2012.
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