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Manus Masked-owl Tyto manusi

This species is restricted to a small island and is very poorly known. Comparison with the congeneric Australian Masked-owl T. novaehollandiae suggests that it probably occurs at low densities and therefore has a very small population which is likely to be declining owing to habitat loss. For these reasons it is classified as Vulnerable. Clarification of its likely subpopulation structure may lead to its uplisting to Endangered in the near future

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

33 cm. Poorly known, medium-sized forest-dwelling owl. Identified by combination of dark upperparts, black tail with narrow yellowish-brown bars and buff underparts with large blackish spots. Similar spp. No other masked-owl in its range. Voice Reported to be duller and harsher than Bismarck Masked-owl T. aurantia.

Distribution and population
Tyto manusi is known only from two historic specimens from Manus in the Admiralty Islands of Papua New Guinea. There are no records of the species since 1934 (P. Gregory in litt. 2012) as recent surveys have failed to locate this species and there are few if any convincing reports from local villagers (Dutson and Newman 1991, D. Gibbs in litt. 1994, G. Dutson pers. obs. 1997). Tyto owls known only from subfossil bones on the adjacent islands of Mussau and New Ireland appear to have become extinct through unknown causes (Steadman and Kirch 1998). As with other Tyto owls, it may have been overlooked, but with further visits to Manus by birdwatchers and a continuing lack of records, its population may be smaller than 1,000 individuals.

Population justification
The population is estimated to number 250-999 mature individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for congeners or close relatives with a similar body size, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 375-1,499 individuals in total, rounded here to 350-1,500 individuals.

Trend justification
This species is presumed to be forest dependent, and consequently moderate and on-going declines are suspected because large areas of Manus have been logged or are under logging concessions.

Tyto manusi is a rare owl of forest interior and has not been found in heavily degraded or swamp forest, although as it is only known from two specimens, it may have wider habitat tolerances. It is poorly known but is assumed to have similar habits to Australian Masked-owl Tyto novaehollandiae. The latter is nocturnal, shy and secretive; it roosts in dense folliage, hollow tree trunks and caves. Australian Masked-owl feeds on small rodents and other small vertebrates and larger insects (König et al. 1999). Manus Masked-owl is likely to have large territories, with a home-range size of between 0.04-1.8 km2 per pair (Higgins 1991).

In 1987, 80% of vegetation on Manus was estimated to be primary forest (Kula et al. undated). Large areas of lowland Manus are now logged or under logging concessions and in coastal areas the forest is being eroded by shifting cultivation. This is not a major threat but could be important for rare endemics such as Tyto manusi that are presumed to have tiny populations and distributions. Introduced mammalian predators, such as dogs and cats, may be implicated in the species's rarity but the brown tree snake Boiga irregularis, which has decimated birds on Guam, is thought to be native to Manus (Dutson and Newman 1991, R. Beck in litt. 1992), and therefore might not pose a serious threat.

Conservation Actions Underway
CITES Appendix II. A large area of uninhabited forest including Mt Dremsel (719 m), has been identified as a very important area of terrestrial biodiversity (Beehler 1993).
Conservation Actions Proposed
Continue surveying to locate the species on Manus. Study the taxonomy of T. manusi and T. novaehollandiae, and compare their ecology and biology (König et al. 1999). Protect areas of suitable habitat.

Beehler, B. M. 1993. Biodiversity and conservation of the warm-blooded vertebrates of Papua New Guinea. In: Beehler, B.M. (ed.), Papua New Guinea - conservation needs assessment, pp. 77-121. Biodiversity Support Program, Washington, DC.

Dutson, G. C. L.; Newman, J. L. 1991. Observations on the Superb Pitta Pitta superba and other Manus endemics. Bird Conservation International 1: 215-222.

Higgins, P. J. 1999. Handbook of Australian, New Zealand and Antarctic birds: parrots to dollarbirds. Oxford University Press, Oxford, U.K.

König, C.; Weick, F.; Becking, J.-H. 1999. Owls: a guide to the owls of the world. Pica Press, Robertsbridge, U.K.

Steadman, D. W.; Kirch, P. V. 1998. Biogeography and prehistoric exploitation of birds in the Mussau islands, Bismarck Archipelago, Papua New Guinea. Emu 98: 13-22.

Text account compilers
Benstead, P., Derhé, M., Dutson, G., Mahood, S., O'Brien, A.

Beck, R., Dutson, G., Gibbs, D., Gregory, M., Hamilton, S., Williams, A., Gregory, P.

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

Recommended citation
BirdLife International (2014) Species factsheet: Tyto manusi. Downloaded from on 19/04/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from 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.

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 Vulnerable
Family Tytonidae (Barn owls)
Species name author Rothschild & Hartert, 1914
Population size 250-999 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 1,900 km2
Country endemic? Yes
Links to further information
- Additional Information on this species