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Tristan Thrush Nesocichla eremita

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.

Taxonomic source(s)
Dowsett, R. J.; Forbes-Watson, A. D. 1993. Checklist of birds of the Afrotropical and Malagasy regions. Tauraco Press, Li
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Distribution and population
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).

Population justification
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.

Trend justification
There is presently no serious threat to the species and no evidence of declines in either its population or range, thus the species's population is currently suspected to be stable.

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).

Threats
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 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.

References
del Hoyo, J.; Elliott, A.; Christie, D. 2005. Handbook of the Birds of the World, vol. 10: Cuckoo-shrikes to Thrushes. Lynx Edicions, Barcelona, Spain.

Fraser, M. W.; Ryan, P. G.; Dean, W. R. J.; Briggs, D. J.; Moloney, C. L. 1994. Biology of the Tristan Thrush Nesocichla eremita. Ostrich 65: 14-25.

Richardson, M. E. 1984. Aspects of the ornithology of the Tristan da Cunha group and Gough Island, 1972-1974. Cormorant 12: 123-201.

Text account compilers
O'Brien, A., Robertson, P., Symes, A., Taylor, J.

Contributors
Rowlands, B., Ryan, P.G.

IUCN Red List evaluators
Butchart, S., Taylor, J.

Recommended citation
BirdLife International (2014) Species factsheet: Nesocichla eremita. Downloaded from http://www.birdlife.org on 23/07/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 23/07/2014.

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.

Additional resources for this species

ARKive species - Tristan thrush (Nesocichla eremita) 0

Key facts
Current IUCN Red List category Near Threatened
Family Turdidae (Thrushes)
Species name author Gould, 1855
Population size 1500-7000 mature individuals
Population trend Stable
Distribution size (breeding/resident) 120 km2
Country endemic? Yes
Links to further information
- Additional Information on this species