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Siau Scops-owl Otus siaoensis
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Justification
This species has not been recorded since the type specimen was collected in 1866, and it was not found during recent surveys since 1998. Very little forest remains and habitat destruction has been extensive and is continuing. However, it cannot be assumed to be Extinct, because there have been some local reports, a thorough survey is required, and some Asian scops-owls survive even in secondary habitats. Any remaining population is likely to be tiny, and for these reasons it is treated as Critically Endangered.

Taxonomic source(s)
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.
Lambert, F. R.; Rasmussen, P. C. 1998. A new scops owl from Sangihe Island, Indonesia. Bulletin of the British Ornithologists' Club 118: 204-217.

Taxonomic note
Otus magicus and O. tempestatis (del Hoyo and Collar 2014) were previously lumped as O. magicus, and O. alfredi, O. siaoensis, O. enganensis, O. insularis and O. beccarii (del Hoyo and Collar 2014) were split from O. magicus following Widodo et al. (1999), Lambert and Rasmussen (1998), Andrew (1992) and Holt et al. (1999). Prior to that all these taxa were lumped in O. magicus following Sibley and Monroe (1990, 1993).

Identification
17 cm. Small, forest-dwelling owl. Typical scops-owl with relatively large head and feet, very finely barred wings and tail. Similar spp. The only scops-owl on Siau. Voice Undocumented. Taxonomy Previously considered conspecific with Moluccan Scops-owl O. magicus, recent research has shown it to be a valid species on the basis of morphological features.

Distribution and population
Otus siaoensis is only known from the holotype collected on the island of Siau, north of Sulawesi, Indonesia, in 1866. Given the small size of this island, and its generally unvegetated volcanic upper reaches, the original population was probably always modest in size, and any surviving population must be tiny, given that little forest remains. There is some suggestion that the species might survive, on the basis of accounts given by local people; however, a recent survey of nocturnal birds in northern Sulawesi spent 32 days on Siau Island and failed to confirm that the species still occurs there. However, semi-structured interviews revealed that small owls do occur on the island and one unidentified call was heard. These reports remain unconfirmed (Hunowi 2006), but a recent sound recording is thought to relate to this species, and further searches are planned (N. Brickle in litt. 2007, 2008, 2012). Several further searches in 2009 failed to locate the species, and the origin of an "owl-like" call recorded in several forest fragments remain uncertain (Sykes 2009).

Population justification
The population is estimated to number fewer than 50 individuals and mature individuals, based on analyses of recent searches and reports, the extent of habitat destruction within its range, and the conclusion that it seems likely that... any surviving population will prove minute.

Trend justification
The population is suspected to be stable in the absence of evidence for any declines or substantial threats.

Ecology
There are no ecological data, although it is reasonable to assume that the species is a forest dweller in common with its close congeners. A call thought to relate to this species has been heard in degraded forest on steep slopes (N. Brickle in litt. 2012).


Threats
Siau is currently experiencing rapid deforestation. In 1995, there was some lowland forest around Lake Kepetta in the south of the island, but this had been felled by 1998. In August 1998, the island was judged to have been largely converted to mixed plantation and scrub, but small patches of low trees survived. In October 1998, a five-day survey determined that only 50 ha of forest remained, all above 800 m on Gunung Tamata, in the centre of the island.

Conservation Actions Underway
CITES Appendix II. In October 1998, five days were spent on the island of Tagulandang, just south of and almost as large as Siau, but only a few hectares of forest were found to remain, all above 600 m. The Wildlife Conservation Society is providing financial and technical support to the North Sulawesi local NGO PALS to conduct extensive surveys of Siau Island to locate the species. If found, immediate conservation measures will be implemented (N. Brickle in litt. 2007, 2008). Conservation Actions Proposed
Survey the remaining forest on Siau and Tagulandang at different times of year, investigating any patch of trees, however remote the possibility of success may seem. In the event of its survival, initiate conservation measures at the site of rediscovery.

References
Andrew, P. 1992. The birds of Indonesia: a checklist (Peters' sequence). Indonesian Ornithological Society, Jakarta.

BirdLife International. 2001. Threatened birds of Asia: the BirdLife International Red Data Book. BirdLife International, Cambridge, U.K.

Holt, D. W.; Berkley, R.; Deppe, C.; Enriquez Rocha, P. L.; Olsen, P. D.; Petersen, J. L.; Rangel Salazar, J. L.; Segars, K. P.; Wood, K. L. 1999. Strigidae (typical owls). In: del Hoyo, J.; Elliott, A.; Sargatal, J. (ed.), Handbook of the birds of the world, pp. 76-242. Lynx Edicions, Barcelona, Spain.

Hunowi, I. 2006. Ghost birds of Sulawesi: surveys and conservation of nightjars and owls. BirdingASIA 6: 7-8.

Lambert, F. R.; Rasmussen, P. C. 1998. A new scops owl from Sangihe Island, Indonesia. Bulletin of the British Ornithologists' Club 118: 204-217.

Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Sibley, C. G.; Monroe, B. L. 1993. A supplement to 'Distribution and taxonomy of birds of the world'. Yale University Press, New Haven, USA.

Widodo, W.; Cox, J. H.; Rasmussen, P. C. 1999. Rediscovery of the Flores Scops Owl Otus alfredi on Flores, Indonesia, and reaffirnation of its specific status. Forktail 15: 15-23.

Further web sources of information
Alliance for Zero Extinction (AZE) species/site profile. This species has been identified as an AZE trigger due to its IUCN Red List status and limited range.

Click here for more information about the Alliance for Zero Extinction (AZE)

Detailed species accounts from the Threatened birds of Asia: the BirdLife International Red Data Book (BirdLife International 2001).

Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Benstead, P., Bird, J., Butchart, S., Derhé, M., Symes, A., Tobias, J., Khwaja, N.

Contributors
Brickle, N.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2014) Species factsheet: Otus siaoensis. Downloaded from http://www.birdlife.org on 21/11/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/11/2014.

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.

Key facts
Current IUCN Red List category Critically Endangered
Family Strigidae (Typical Owls)
Species name author (Schlegel, 1873)
Population size 1-49 mature individuals
Population trend Unknown
Distribution size (breeding/resident) 120 km2
Country endemic? Yes
Links to further information
- Additional Information on this species