VU
Biak Scops-owl Otus beccarii



Justification

Justification of Red List Category
This species has been downlisted to Vulnerable on the basis that its habitat is not as fragmented as once thought, along with evidence that it is more widespread than previously thought. Nevertheless, its population is estimated to be small and inferred to be in on-going decline.

Population justification
The population is estimated to number 2,500-9,999 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 3,750-14,999 individuals, rounded here to 3,500-15,000 individuals. It is assumed that all mature individuals are in a single sub-population (G. Dutson in litt. 2013).

Trend justification
The widespread loss of forest on the island of Biak suggests that the species has declined, but parts of Supiori are virtually impenetrable and as such may provide a refuge. Based on this information, the population is suspected to be declining at a moderate rate.

Distribution and population

Otus beccarii is endemic to the twin islands of Biak-Supiori in Geelvink Bay, Papua (formerly Irian Jaya), Indonesia (Mayr and Meyer de Schauensee 1939, Marshall 1978, Konig et al. 1999, Marks et al. 1999). Its status is uncertain, as it is a nocturnal species with poorly-known calls and only recently considered to be a separate species. A survey of the island in 1973 found only one pair (S. D. Ripley in litt. to Clark and Mikkola 1989), and it was not recorded during three visits to Biak in the 1990s (Gibbs 1993, Poulsen and Frolander 1994, Eastwood 1996b). One was heard in and around Biak-Utara Reserve in 1997 (B. Beehler and S. van Balen in litt. 2000), and two were heard one morning in 1995 (M. Van Beirs in litt. 2000). However, more recently, the species has been encountered regularly in remnant forest patches in southern Biak (K. D. Bishop in litt. 2012). Subsequently, it has been suggested that this species is widespread in forested habitats around Biak and Supiori (B. Beehler in litt. 2012, G. Dutson in litt. 2013).

Ecology

It inhabits forest, including partially logged forest, up to at least 300 m (Bishop 1982, Marks et al. 1999, B. Beehler and S. van Balen in litt. 2000, M. Van Beirs in litt. 2000), and can be found in coastal swamp-forest bounded by heavily forested limestone cliffs (Marshall 1978).

Threats

Large areas of forest on Biak have been destroyed or damaged by logging and cleared for subsistence farming, particularly in the southern plains, and the remainder is under pressure (Bishop 1982, K. D. Bishop in litt. 1996, D. Holmes in litt. 2000). Furthermore, forest does not regenerate easily on areas of raised coralline limestone. Much of Supiori comprises virtually impenetrable forest on limestone mountains, which is likely to be safe from habitat degradation.

Conservation actions

Conservation Actions Underway
CITES Appendix II. There are two protected areas on the islands, Biak-Utara (110 km2) and Pulau Supiori (420 km2) Nature Reserves (Sujatnika et al. 1995).

Conservation Actions Proposed
Identify and record the species's vocalisations to aid detection. Conduct surveys on both Biak and Supiori, using tape-playback of vocalisations, to establish its current distribution, population status and assess its habitat requirements. Investigate further its taxonomic status and relationship to other Otus species. Afford formal protection to key sites supporting the species, as appropriate.

Identification

25 cm. Tawny-brown owl with short, inconspicuous ear-tufts. Yellow eyes. Rather distinct, pale whitish eyebrows and facial disc. Densely barred brown upperparts with some white on scapulars. Brown or rich rufous underparts, probably colour morphs but possibly sex dimorphism, with very fine barring. Similar spp. The only owl on Biak-Supiori. Papuan Frogmouth Podargus papuensis and Large-tailed Nightjar Caprimulgus macrurus have different habits and long tails. Voice Probably a harsh croak, rasping at close range but sounding more like a deer's bark at long range. Hints Calling birds can usually be stalked and seen in the beam of a torch.

Acknowledgements

Text account compilers
Allinson, T, Benstead, P., Bird, J., Dutson, G., Symes, A. & Taylor, J.

Contributors
Beehler, B., Bishop, K., Dutson, G., Holmes, D., Ripley, S., van Balen, B. & van Beirs, M.


Recommended citation
BirdLife International (2019) Species factsheet: Otus beccarii. Downloaded from http://www.birdlife.org on 21/07/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/07/2019.