Troglodytes sissonii


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Troglodytes sissonii
Species Authority: (Grayson, 1868)
Common Name(s):
English Socorro Wren
Thryomanes sissonii BirdLife International (2004)
Thryomanes sissonii Stotz et al. (1996)
Thryomanes sissonii Collar and Andrew (1988)
Thryomanes sissonii Collar et al. (1994)
Thryomanes sissonii BirdLife International (2000)
Thryomanes sissonii Sibley and Monroe (1990, 1993)
Thryomanes sissonii AOU checklist (1998 + supplements)
Taxonomic Notes: Formerly placed in the genus Thryomanes. Use of the genus Troglodytes follows Martínez Gómez et al. (2005).

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Keitt, B., Martínez-Gómez, J. & Tershy, B.
Facilitator/Compiler(s): Capper, D., Harding, M., Isherwood, I., O'Brien, A., Sharpe, C J, Taylor, J.
This species is listed as Near Threatened because it has an extremely small range on one island, but it remains very common. Any evidence of a decline in the population would qualify it for a higher threat category.

Geographic Range [top]

Range Description: Troglodytes sissonii inhabits arid lowland scrub and semi-deciduous forest on Isla Socorro (c.150 km2) in the Revillagigedo Islands, Mexico (Howell and Webb 1995). It was described as the second most common landbird on the island in 1991 (Santaella and Sada 1991) and remains very common at all elevations (J. Martínez Gómez in litt. 1998).

Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Partners in Flight estimated the population to number fewer than 50,000 individuals (A. Panjabi in litt. 2008), thus it is placed in the band 20,000-49,999 individuals here.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: This species inhabits woodland and brushy hillsides (del Hoyo et al. 2005). Its diet is unknown, but it has been observed foraging low in vegetation, on the ground, and on tree trunks. Families with fledged young have been observed in April, suggesting early breeding. One nest has been found in the knothole of a decayed tree (del Hoyo et al. 2005).

Systems: Terrestrial

Threats [top]

Major Threat(s): The proliferation of sheep on the island since the 19th century has led to deforestation of large parts of the southern lowlands, where the species is no longer common (J. Martínez Gómez in litt. 1998). Until sheep are eradicated from the island or effectively controlled, the continuing effect of intensive grazing may reduce its already very small range. There is no direct evidence that it is preyed upon by Socorro Mockingbird Mimodes graysoni (J. Martínez Gómez in litt. 1998 contra Parkes 1990).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
The eradication of sheep was planned for 2008-2009 (B. Tershy in litt. 2007).

Conservation Actions Proposed
Carry out surveys to assess the population size. Monitor population trends through regular surveys. Eradicate sheep from Socorro.

Citation: BirdLife International 2012. Troglodytes sissonii. The IUCN Red List of Threatened Species. Version 2015.2. <>. Downloaded on 30 August 2015.
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