• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Justification of Red List category
This species is listed as Vulnerable because it is restricted to a very small range on just two small islands where the accidental introduction of mammals could drive it to extinction in a very short period, as has happened on other islands in its former range.

Population justification
It is thought that there were over 500 mature individuals on Disappointment Island in 1993 (Walker et al. 2020), and the species was recorded on 46% of complete bird lists between 1972 and 2018 (Miskelly et al. 2020), indicating that within its very limited range on the island it is common. On Adams Island, where suitable habitat may cover as little as 10% of the island (Elliott et al. 1991), the population was estimated at approximately 1,500 mature individuals by Heather and Robertson (1997), recorded on 27% of complete bird lists between 1972 and 2018 (Miskelly et al. 2020). The population is currently thought to be stable (Robertson et al. 2021), and with no recent survey data to indicate a decline or increase in population size since these estimates were made, the population is estimated to number c.2,000 mature individuals.

Trend justification
There are no new data on population trends; however, the species is suspected to have remained stable within the last three generations (Robertson et al. 2013, 2017, 2021).

Lewinia muelleri is endemic to the Auckland Islands, New Zealand. It was once thought to be extinct but was rediscovered on Adams Island (100 km²) in 1966 and Disappointment Island (4 km²) in 1993. It is likely that they historically occurred on most of the Auckland Islands but vegetation changes, predation and competition from introduced species is thought to have caused their extirpation (Elliott 2013).

Its preferred habitat consists of coastal and cliff herbfields, Carex grassland, tussock-herbfields and forest. The one clutch seen in the wild consisted of two eggs (Elliott et al. 1991). On both islands L. muelleri is most often heard and seen in areas dominated by the megaherbs Anisotome latifolia, A. antipoda, Pleurophyllum criniferum, P. speciosum, and Stilbocarpa polaris (Miskelly et al. 2020). These plants are highly susceptible to browsing and uprooting by ungulates, rabbits, and pigs and the loss of these plants from islands in Port Ross may have contributed to the local extinction of rails. One juvenile bird caught in the wild lived for nine years in captivity, and ate insects and other invertebrates (Heather and Robertson 1997, Taylor and van Perlo 1998).

Although both rail-inhabited islands are free of introduced predators, Auckland Island (a few hundred metres from Adams, where c.75% of the species now exists) supports feral cats, mice and pigs, and therefore the introduction of these animals is a plausible threat and is the likely reason for the absence of the species on other islands in the Auckland Islands group. The megaherbs on which the species depends are highly susceptible to uprooting by ungulates, rabbits and pigs and may limit the short-term potential of restoration and re-colonisation of other islands. They are also predated by New Zealand falcons Falco novaeseelandiae (Hyde and Worthy 2010).

Conservation Actions Underway
The islands are nature reserves part of a World Heritage Site declared in 1998 and access is strictly controlled. Both islands this species persists on are subject to strict biosecurity measurements to minimise the risk of introducing non-native species.

Conservation Actions Proposed
Conduct surveys to obtain an up-to-date estimate of the population size. Monitor population trends through regular surveys. Eradicate pigs from Auckland Island in the long term (B. D. Bell verbally 1999, A. D. Roberts in litt. 1999). Transfer birds to other suitable pest-free islands in the Auckland Island group (A. D. Roberts in litt. 1999).

21 cm. Small, chestnut-brown rail. Chestnut back, uppertail, wings, streaked with black. Red/brown sides of head. Grey breast, flanks, undertail barred black-and-white. Sexes alike. Voice Loud crek rapidly repeated c.10 times, loud, sharp, short whistle repeated c.50 times in about 12 seconds.

Text account compilers
Benstead, P., Berryman, A., McClellan, R., Mahood, S., Khwaja, N., Vine, J., Taylor, J.

Contributors
Bell, B.D. & Roberts, A.D.

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Recommended citation
BirdLife International (2024) Species factsheet: Auckland Island Rail Lewinia muelleri. Downloaded from https://datazone.birdlife.org/species/factsheet/auckland-island-rail-lewinia-muelleri on 23/12/2024.
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 23/12/2024.