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Nesocichla eremita

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA AVES PASSERIFORMES TURDIDAE

Scientific Name: Nesocichla eremita
Species Authority: Gould, 1855
Common Name(s):
English Tristan Thrush

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): Taylor, J. & Butchart, S.
Contributor(s): Rowlands, B. & Ryan, P.G.
Facilitator/Compiler(s): O'Brien, A., Robertson, P., Symes, A., Taylor, J.
Justification:
This species is classed as Near Threatened because it has a small population, which occupies a restricted range. There is presently no serious threat to the species and no evidence of declines in either its population or range, but if such evidence was obtained this species might qualify for a higher threat category.

Geographic Range [top]

Range Description: Nesocichla eremita is endemic to Tristan da Cunha (to UK) in the South Atlantic Ocean, where it is found on Tristan, Inaccessible, Nightingale, Middle and Stoltenhoff islands with distinct subspecies on each of the three main islands. In 1972-1974, island population sizes were estimated as follows (in pairs): Tristan 40-60; Inaccessible 100-500; Nightingale 300-500; Middle 20-40; and Stoltenhoff 10-20 (Richardson 1984). In the 1980s, the Inaccessible population was revised to 850 pairs, and the total population for the group to 6,000 birds (Fraser et al. 1994). More recently, the Tristan population has been estimated (very crudely, but conservatively) as at least several hundred birds (P. G. Ryan in litt. 2000).

Countries:
Native:
Saint Helena, Ascension and Tristan da Cunha
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: In 1972-1974, island population sizes were estimated as follows (in pairs): Tristan 40-60; Inaccessible 100-500; Nightingale 300-500; Middle 20-40; and Stoltenhoff 10-20. In the 1980s, the Inaccessible population was revised to 850 pairs, and the total population for the group to 6,000 birds. More recently, the Tristan population has been estimated (very crudely, but conservatively) as at least several hundred birds (P. G. Ryan in litt. 2000). It is best placed in the band 2,500-9,999 individuals, equating to 1,667-6,666 mature individuals, rounded here to 1,500-7,000 mature individuals.
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology: The species uses virtually all available habitats including boulder-strewn shorelines, tussock grassland, fern-bush and wet heath. It feeds opportunistically on dead birds, fish offal, kitchen scraps and the eggs and fledglings of other birds as well as earthworms and invertebrates taken from leaves and detritus (Fraser et al. 1994, del Hoyo et al. 2005). Breeding takes place in September-February (del Hoyo et al. 2005). Its nest is a rough cup of woven tussock fronds and grass stalks with some moss and leaves, placed on or just above the ground. It lays two or three, sometimes four, eggs. The fledging period is c.20 days (del Hoyo et al. 2005).

Systems: Terrestrial; Marine

Threats [top]

Major Threat(s): On Tristan, predation by black rats Rattus rattus is a possible threat. Translocations of birds between islands, a common practice in the past, resulting in hybridisation, is another concern (P. G. Ryan in litt. 2000).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
Cats were a major problem on Tristan, but have been eradicated (del Hoyo et al. 2005).

Conservation Actions Proposed
Carry out surveys to obtain an up-to-date total population estimate. Monitor population trends through regular surveys. Assess the impact of predation by rats. Control rat numbers on Tristan, and prevent further introductions of mammalian predators. Legislate against the transportation of the species between islands.


Citation: BirdLife International 2012. Nesocichla eremita. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 19 September 2014.
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