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VU
Inaccessible Rail Atlantisia rogersi

Justification
This species, the smallest flightless bird in the world, qualifies as Vulnerable because, although abundant, it is restricted to one tiny island and is at permanent risk from chance events such as the accidental introduction of alien predators.

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.

Identification
17 cm. Small, very dark rail. Dark grey on underparts and dark rusty-brown on upperparts. Short black bill, greyish legs and red eye. Immature is overall brownish in colour with dark eye. Adults show various degrees of white barring on flanks and belly. Voice Loud, trilling call, various soft contact tchik calls, and harsh, loud chip alarm call.

Distribution and population
Atlantisia rogersi is confined to the South Atlantic island of Inaccessible, Tristan da Cunha (St Helena to UK). The population has been variously estimated as 1,200 birds in 1938 (Hagen 1952), 5,000-10,000 birds in 1952 (Elliott 1957) and 1,000-2,000 breeding pairs in 1974 (Richardson 1984). The most accurate survey to date gave an estimate of 8,400 birds (Fraser et al. 1992). It is abundant on the island and may be at carrying capacity given its high population density, delayed maturity, small clutch-size, and lack of major predators or competitors (Fraser et al. 1992, Taylor and van Perlo 1998).

Population justification
The most accurate survey to date gave an estimate of 8,400 birds, roughly equivalent to 5,600 mature individuals.

Trend justification
The population is suspected to be stable in the absence of any immediate and serious threats.

Ecology
Behaviour This species is sedentary and flightless (Taylor and van Perlo 1998, del Hoyo et al. 1996). It is monogamous, and lives in family groups (Collar and Stuart 1985), holding small territories at a density of up to 10-15 birds per hectare in good quality habitat (Taylor and van Perlo 1998, P. G. Ryan in litt. 2000). Breeding occurs from October to January (P. G. Ryan in litt. 2000). Habitat It occurs virtually throughout the island, on most vegetation types, at all altitudes, and even on the steepest slopes (Taylor and van Perlo 1998). Breeding Breeding has been recorded in coastal tussock-grass Spartina arundinacea, especially where this is mixed with the fern Blechnum penna-marina to form luxurian undergrowth and mats of vegetation (Collar and Stuart 1985, Taylor and van Perlo 1998). Nests have also been found in beds of sedge on the plateau (Collar and Stuart 1985), where the species often occurs in open fern-bush habitats and island-tree thickets, generally away from the cliffs (P. G. Ryan in litt. 2000). It inhabits heathland at the island's highest altitudes (Taylor and van Perlo 1998). In general it prefers areas where vegetation, boulders or other landscape features at ground level provide tunnels in which to shelter and to breed (Collar and Stuart 1985). Non-breeding It forages in every available habitat including very short vegetation, boulder beaches and marshy areas (Fraser et al. 1992). It is absent from one site of short dry tussocks on cinder cones (Collar and Stuart 1985, Taylor and van Perlo 1998). Diet The diet comprises a wide range of invertebrates including earthworms and moths, centipedes, and a wide variety of insects and insect larvae, as well as berries and seeds (Collar and Stuart 1985, Taylor and van Perlo 1998). Breeding site Nests are built on the ground beneath a dense cover of vegetation (Taylor and van Perlo 1998). They are carefully woven from the vegetation in which they are sited, usually oval or pear-shaped, and accessed via a track or tunnel extending for up to 50cm through the vegetation (Taylor and van Perlo 1998). A clutch consists of two eggs (P. G. Ryan in litt. 2000).

Threats
Predation by Tristan Thrush Nesocichla eremita and wet weather are believed to be the main causes of chick mortality, but pose no real threat. However, there is a permanent risk that the island will be colonised by mammalian predators, particularly the black rat Rattus rattus from Tristan. The colonisation of potential competitors would also be a threat, as well as alien invertebrates which could negatively modify the prey base (P. G. Ryan in litt. 1999). Despite its name, the island is now more accessible to islanders via a fisheries patrol vessel based at Tristan (P. G. Ryan in litt. 1999).

Conservation Actions Underway
Inaccessible is a nature reserve and, although Tristan Islanders retain the right to collect driftwood and guano, other access is restricted (Cooper et al. 1995). A management plan for the island was due for comment in 2000 (P. G. Ryan in litt. 1999). Conservation Actions Proposed
Conduct surveys to obtain an up-to-date population estimate. Monitor population trends through regular surveys. Carry out research to identify and quantify the main causes of natural mortality. Minimise the risk of colonisation by introduced species through strict controls on visits (P. G. Ryan in litt. 1999). Promote awareness about the dangers of alien species introduction through inter-island transfers (P. G. Ryan in litt. 1999). Establish a captive-breeding population for research and advocacy. Nominate Inaccessible for World Heritage Site status (J. Cooper in litt. 1999).

References
Collar, N. J.; Stuart, S. N. 1985. Threatened birds of Africa and related islands: the ICBP/IUCN Red Data Book. International Council for Bird Preservation, and International Union for Conservation of Nature and Natural Resources, Cambridge, U.K.

Cooper, J.; Ryan, P. G.; Andrew, T. G. 1995. Conservation status of the Tristan da Cunha Islands. In: Dingwall, P.R. (ed.), Progress in conservation of the subantarctic islands, pp. 59-70. IUCN-World Conservation Union, Gland, Switzerland.

del Hoyo, J.; Elliott, A.; Sargatal, J. 1996. Handbook of the Birds of the World, vol. 3: Hoatzin to Auks. Lynx Edicions, Barcelona, Spain.

Elliott, H. F. I. 1957. A contribution to the ornithology of the Tristan da Cunha group. Ibis 99: 545-586.

Fraser, M. W.; Dean, W. R. J.; Best, I. C. 1992. Observations on the Inaccessible Island Rail Atlantisia rogersi: the world's smallest flightless bird. Bulletin of the British Ornithologists' Club 112: 12-22.

Hagen, Y. 1952. Birds of Tristan da Cunha. Results of the Norwegian Scientific expedition to Tristan da Cunha. 1937-1938. No 20. Norske Videnskaps-Akademi, Oslo.

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

Taylor, B. 1998. Rails: a guide to the rails, crakes, gallinules and coots of the world. Pica Press, Robertsbridge, UK.

Text account compilers
Ekblom, R., McClellan, R., Shutes, S., Stattersfield, A., Symes, A., Taylor, J.

Contributors
Cooper, J., Ryan, P.G.

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

Recommended citation
BirdLife International (2014) Species factsheet: Atlantisia rogersi. Downloaded from http://www.birdlife.org on 19/04/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/04/2014.

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.

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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 - Inaccessible rail (Atlantisia rogersi) 0

Key facts
Current IUCN Red List category Vulnerable
Family Rallidae (Rails, crakes and allies)
Species name author Lowe, 1923
Population size 5600 mature individuals
Population trend Stable
Distribution size (breeding/resident) 16 km2
Country endemic? Yes
Links to further information
- Additional Information on this species