Biak Scops-owl (Otus beccarii): downlist to Vulnerable or Near Threatened?

This discussion was first published as part of the 2013 Red List update, but remains open for comment to enable reassessment in 2014.

BirdLife species factsheet for Biak Scops-owl

Biak Scops-owl Otus beccarii is restricted 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). It is currently listed as Endangered under criterion B1ab(ii,iii,v), on the basis that it has a very small range of <5,000 km2, in which it is restricted to tall lowland forest, which is severely fragmented and continuing to decline.  There are very few records of this species and its status is unclear, as it is nocturnal, with poorly-known calls and only recently considered to be a separate species. A survey of the islands in 1973 found only one pair (S. D. Ripley in litt. to Clark and Mikkola 1989), 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, new information suggests that this species may be more common and widespread than previously thought. Visiting birders recently claim to have encountered the species regularly in remnant forest patches in southern Biak (K. D. Bishop in litt. 2012). It has also been suggested that this species is widespread in forested habitats around Biak and Supiori (B. Beehler in litt. 2012). Furthermore, the forested areas in Supiori are continuous and thus, do not appear to be fragmented as once thought (B. Beehler in litt. 2012). If the evidence that the species is more widespread than previous estimates suggest is confirmed, and its Extent of Occurrence (EOO) is <20,000 km2, it is not severely fragmented but is still found at ≤10 locations, and is continuing to decline, this species would warrant downlisting to Vulnerable under criterion B1ab(ii,iii,v). If its global population is still <10,000 mature individuals, and all subpopulations are ≤1,000 mature individuals, this species would qualify for downlisting to Vulnerable under criterion C2a(i). If, however, all mature individuals are in one subpopulation, this species could qualify as Vulnerable under criterion C2a(ii). Should the species approach, but not reach the thresholds for Vulnerable under the range and population size criterion, it would warrant downlisting to Near Threatened.

Further information is required on this species’s distribution, habitat requirements, population size and size of the largest subpopulation.

References:

Clark, R. J. and Mikkola, H. (1989) A Preliminary Revision of Threatened and Near-threatened Nocturnal Birds of Prey of the World. Raptors in the Modern World, pp. 371-388. WWGBP: Berlin, London & Paris.

Eastwood, C. (1996) A trip to Irian Jaya. Muruk 8(1): 12-23.

Gibbs, D. (1993) Irian Jaya, Indonesia, 21 January–12 March 1991: a site guide for birdwatchers, with brief notes from 1992.

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

Marks, J. S., Cannings, R. J. and Mikkola, H. (1999) Family Strigidae (Typical Owls). In: del Hoyo, J., Elliott, A. and Sargatal, J. (eds.), Handbook of the birds of the world, pp. 76-242. Barcelona, Spain: Lynx Edicions.

Marshall, J. T. (1978) Systematics of smaller Asian night birds based on voice. American Ornithologists’ Union: Kansas.

Mayr, E. and Meyer de Schauensee, R. (1939) Zoological results of the Denison-Crockett Expedition to the south Pacific for the Academy of Natural Sciences of Philadelphia, 1937-1938. Part 1: the birds of the Island of Biak. Proceedings of the Academy of Natural Sciences of Philadelphia 91: 1-37.

Poulsen, B. O. and Frolander, A. (1994) Birding Irian Jaya, Indonesian New Guinea.

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  1. Philippine Scops-owl (Otus megalotis) is being split: list O. nigrorum as Vulnerable and O. megalotis and O. everetti as Near Threatened?
  2. Archived 2012-2013 topics: Victoria Crowned-pigeon (Goura victoria): downlist to Near Threatened?
  3. Javan Trogon (Apalharpactes reinwardtii): downlist to Vulnerable?
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3 Responses to Biak Scops-owl (Otus beccarii): downlist to Vulnerable or Near Threatened?

  1. Guy Dutson says:

    Having lead a couple of birding tours to Biak and reviewed the birding literature, i conclude that our knowledge of this species is extrapolated from only a handful of calling birds. I does seem to be uncommon and/or unobtrusive (i.e. it rarely calls) but probably widespread across tall forest. I suggest that all mature individuals are in one subpopulation.

  2. Andy Symes says:

    Preliminary proposals

    Based on available information and comments posted above, our preliminary proposal for the 2014 Red List would be to treat Biak Scops-owl Otus beccarii as Vulnerable under criterion C2a(ii).

    There is now a period for further comments until the final deadline of 31 March, after which recommended categorisations will be put forward to IUCN.

    The final Red List categories will be published on the BirdLife and IUCN websites in mid-2014, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  3. Andy Symes says:

    Recommended categorisation to be put forward to IUCN

    Following further review, there has been no change to our preliminary proposal for the 2014 Red List status of this species.

    The final categorisation will be published later in 2014, following further checking of information relevant to the assessment by BirdLife and IUCN.

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