CR (PE)
Olomao Myadestes lanaiensis



Justification

Justification of Red List Category
The last confirmed sighting of this species was in 1980 (Pyle and Pyle 2017), with unconfirmed reports in 1988, 1994 and 2005, and no subsequent records despite further surveys in most of the historical range in Kamako'u-Pelekunu. It may have been driven extinct by diseases spread by introduced mosquitoes and habitat destruction. A set of papers published in 2017 (Akcakaya et al. 2017, Keith et al. 2017, Thompson et al. 2017) laid out methods for quantitatively estimating a species’s probability of extinction based on parameters associated with threats, in addition to records and surveys. Based on the application of these methods (Butchart et al. 2018), this species would qualify for reclassification as Critically Endangered. However, the authors recommended retaining it as Critically Endangered (Possibly Extinct) because the final site for the species (the Olokui natural area reserve) is only 6.6 km2, less than half of which is suitable habitat, and it has been isolated for so long that it is highly unlikely that any population has persisted.

Population justification
Any remaining population is assumed to be tiny (numbering fewer than 50 individuals and mature individuals), with no confirmed records since 1980.

Trend justification
The population trend is unknown as the last confirmed sighting of this species took place in 1980.

Distribution and population

Myadestes lanaiensis is endemic to the central Hawaiian Islands, U.S.A., where it is (or was) known from Maui, Lana'i and Moloka'i. The nominate subspecies of Lana'i was last seen in 1933 and is now extinct. The race rutha of Moloka'i and Maui is also likely to be extinct (Clement and Hathway 2000). It had been extirpated from Maui before ornithologists arrived, but possibly survived until the mid-19th century (J. Lepson in litt. 1999). Most of the historical range on Moloka'i in Kamako'u-Pelekunu has been resurveyed and the species has probably been extirpated from that area (DOFAW and PIERC 1995, Reynolds and Snetsinger 2001); the last confirmed record from Moloka'i was in 1980 (Pyle and Pyle 2017). However, the species cannot yet be presumed to be Extinct, because the remote Oloku'i Plateau has not been resurveyed recently and could conceivably still harbour some birds. However, at the moment visits to this area are discouraged to prevent any introduction of invasive species. No more than half of the Natural Area Reserve represents suitable habitat (E. VanderWerf in litt. 2017). Any remaining population is likely to be tiny.

Ecology

It is a shy and retiring bird of the montane forest canopy, although in the late 1800s it was reported as ubiquitous in forests from the lowlands to the higher elevations on Moloka'i and Lana'i (Scott et al. 1986, Wakelee and Fancy 1999). Like its congeners, it is primarily frugivorous (Wakelee and Fancy 1999, K. Wakelee in litt. 1999).

Threats

This species's drastic decline is probably attributable to the introduction of disease-carrying mosquitoes and habitat destruction. Mosquitoes were, until recently, restricted to the lowlands, but have followed the penetration of feral pigs into remote native rainforests over the last 25 years (Pratt 1994). The uplands of Moloka'i are probably too small to provide disease-free refugia. Apart from spreading the parasite Plasmodium relictum throughout the Olomao's range, pigs also modify native forests, as they carry alien weeds to new areas, whose rooting destroys the shrub layer (Pratt 1994). Habitat degradation through introduced Axis Deer Axis axis pose an additional threat (Loope and Medeiros 1995).

Conservation actions

Conservation Actions Underway

The Kamakou Preserve and neighbouring land have been partially fenced and control programmes exist for feral ungulates (H. Baker and P. Baker in litt. 1999). The Oloku'i Natural Area, established in 1986, protects pristine native forest (Scott et al. 1986) where M. lanaiensis may persist (Wakelee and Fancy 1999).

Conservation Actions Proposed

Conduct surveys to locate any remaining individuals and, if found, urgently assess actions required for the species's recovery. However, care should be taken and currently visits to the Oloku'i Plateau are discouraged to prevent any introduction of invasive species (E. VanderWerf in litt. 2017). Should it be rediscovered, consideration should be given to establishing a captive population at high elevation on East Maui, where the habitat is relatively intact and free of threat from mosquitoes and avian disease (USFWS 2003).

Identification

18 cm. Small, drab thrush. Brown above, pale grey below, darkest on throat. Pale buff undertail-coverts. Similar spp. Introduced Melodious Laughingthrush Garrulax canorus brighter cinnamon-brown with yellow bill. Introduced Japanese Bush-warbler Cettia diphone much smaller and slimmer with noticeable pale eyebrow. Voice Song a halting, thrush-like melody. Call a cat-like rasp.

Acknowledgements

Text account compilers
Symes, A., Stuart, T., Butchart, S., Isherwood, I., Smith, D., Khwaja, N., Stattersfield, A., Derhé, M., Westrip, J., Bird, J., Benstead, P., Harding, M.

Contributors
Baker, H.C., Baker, P.E., Lepson, J., VanderWerf, E. & Wakelee, K.


Recommended citation
BirdLife International (2019) Species factsheet: Myadestes lanaiensis. Downloaded from http://www.birdlife.org on 14/12/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 14/12/2019.