Data Zone
Justification of Red List category
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.
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.
This species 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).
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). 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).
On Tristan, predation by black rats Rattus rattus is a possible threat. Translocations of birds between islands was a common practice in the past, and may have resulted in hybridisation between birds from different islands (P. G. Ryan in litt. 2000). However, these translocations no longer takes place (A. Bond in litt. 2016).
Conservation Actions Underway
Cats were a major problem on Tristan, but were eradicated (Richardson 1984).
Text account compilers
O'Brien, A., Robertson, P., Symes, A., Taylor, J. & Stringer, C.
Contributors
Rowlands, B., Ryan, P.G. & Bond, A.
Recommended citation
BirdLife International (2024) Species factsheet: Tristan Thrush Turdus eremita. Downloaded from
https://datazone.birdlife.org/species/factsheet/tristan-thrush-turdus-eremita on 23/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/11/2024.