Archived 2014 discussion: Sulawesi Scops-owl (Otus manadensis) is being split: list O. mendeni and O. sulaensis as Vulnerable?

The initial deadline for comments on this topic is 10 March 2014, and therefore later than for most other topics currently under discussion.

This is part of a consultation on the Red List implications of extensive changes to BirdLife’s taxonomy for non-passerines

Lynx Edicions and BirdLife International will soon publish the HBW-BirdLife Illustrated Checklist of the Birds of the World, building off the Handbook of the Birds of the World series, and BirdLife’s annually updated taxonomic checklist.

The new Checklist will be based on the application of criteria for recognising species limits described by Tobias et al. (2010). Full details of the specific scores and the basis of these for each new taxonomic revision will be provided in the Checklist.

Following publication, an open and transparent mechanism will be established to allow people to comment on the taxonomic revisions or suggest new ones, and provide new information of relevance in order to inform regular updates. We are also actively seeking input via a discussion topic here regarding some potential taxonomic revisions that currently lack sufficient information.

The new Checklist will form the taxonomic basis of BirdLife’s assessments of the status of the world’s birds for the IUCN Red List. The taxonomic changes that will appear in volume 1 of the checklist (for non-passerines) will begin to be incorporated into the 2014 Red List update, with the remainder, and those for passerines (which will appear in volume 2 of the checklist), to be incorporated into subsequent Red List updates.

Preliminary Red List assessments have been carried out for the newly split or lumped taxa. We are now requesting comments and feedback on these preliminary assessments.

Sulawesi Scops-owl Otus manadensis is being split into O. manadensis, O. mendeni and O. sulaensis, following the application of criteria set out by Tobias et al. (2010).

Prior to the taxonomic change, O. manadensis (BirdLife species factsheet) was listed as being of Least Concern, on the basis that it was not thought to approach the thresholds for Vulnerable under any of the IUCN Red List criteria.

O. sulaensis is endemic to the Sula Islands, including Taliabu, Scho, Mongole and Sanana, where it inhabits forest, degraded habitats and swamps with trees and bushes, mostly in the lowlands (König and Weick 2008). The species is described as common and frequently encountered, occurring from sea-level to 1,100 m in primary, disturbed, selectively-logged and heavily degraded forest (Davidson et al. 1995, Stones et al. 1997, Rheindt 2010).

Despite its tolerance of modified habitats, the species could be threatened by habitat loss. In the 1990s, it was reported that a substantial proportion of Taliabu was still forested, but that since 1970 large-scale logging of lowland forest had taken place, principally selective logging but also clear-felling of some areas (Davidson et al. 1995). It was also reported that most forest below 800 m was under logging concession and that other threats to forest included the expansion of shifting and permanent agriculture (Davidson et al. 1995). Following a visit in 2009, Rheindt (2010) speculated that all primary forest could have been lost from Taliabu due to the widespread activities of logging companies, with some areas converted to plantations, cultivation and gardens and further conversion to agriculture expected. In addition, forest fires have severely reduced and degraded montane forest on Taliabu (Rheindt 2010).

The species’s population size has apparently not been estimated; however, it may number fewer than 10,000 mature individuals. If all mature individuals are thought to be in one subpopulation (in which adjacent groups in the population are likely to exchange at least two individuals per year) and a population decline is inferred on the basis of on-going habitat loss, the species may qualify as Vulnerable under criterion C2a(ii). If the species is thought to approach these thresholds, it may qualify as Near Threatened under the same criterion.

O. mendeni is endemic to Peleng in the Banggai Islands (König and Weick 2008). Its habitat preferences are apparently unclear, although if it mirrors populations on Sulawesi it inhabits humid forest, scrub and wooded areas in cultivated landscapes (König and Weick 2008). This would suggest a substantial tolerance of habitat modification, and indeed Indrawan et al. (1997) report hearing the species in an area of degraded lowland forest. It may, however, be threatened by habitat loss. By 1991, logging had begun in the last remaining areas of primary habitat on Peleng, which is expected to lead to further encroachment by shifting cultivators as a result of improved access (Indrawan et al. 2010). Exploration by mining companies could lead to more habitat loss on Peleng in the near future (M. Indrawan in litt. 2007, 2008).

The population of O. mendeni has apparently not been quantified, although it may number fewer than 10,000 mature individuals. If all mature individuals are thought to be in one subpopulation (in which adjacent groups in the population are likely to exchange at least two individuals per year) and a population decline is inferred on the basis of continued habitat loss, the species may qualify as Vulnerable under criterion C2a(ii). If the species is thought to approach these thresholds, it may qualify as Near Threatened under the same criterion.

O. manadensis (as defined following the taxonomic change) is widespread on Sulawesi, where it occupies humid forest, lightly wooded agricultural areas and scrub, from the lowlands to c.2,500 m (König and Weick 2008). It is described as locally relatively common, but threatened by forest destruction (König and Weick 2008), thus it may be in decline. However, the rate of forest loss on Sulawesi has been estimated at 10.8% from 2000 to 2010 (Miettinen et al. 2011), thus it is thought very unlikely that the species’s population is undergoing a decline approaching 30% over a period of three generations, estimated at c.11 years for this species, especially considering the species’s apparent tolerance of modified habitats. It is therefore suggested that the species be considered of Least Concern, on the basis that it is not thought to approach the thresholds for Vulnerable under any of the IUCN Red List criteria.

Comments are invited on these suggested categories and further information would be welcomed.

References:

Davidson, P., Stones, T. and Lucking, R. (1995) The conservation status of key bird species on Taliabu and the Sula Islands, Indonesia. Bird Conservation International 5: 1–20.

Indrawan, M., Masala, Y., Dwiputra, D., Mallo, F. N., Maleso, A., Salim, A., Masala, F., Tinulele, I., Pesik, L., Katiandagho and Sunosol, D. S. (2010) Rediscovery of the Critically Endangered Banggai Crow Corvus unicolor on Peleng Island, Indonesia, part 1: ecology. Bulletin of the British Ornithologists’ Club 130(3): 154­–165.

Indrawan, M., Masala, Y. and Pesik, L. (1997) Recent bird observations from the Banggai Islands. Kukila 9: 61–70.

König, C. and Weick, F. (2008) Owls of the World. Second Edition. London, UK: Christopher Helm.

Miettinen, J., Chenghua Shi and Soo Chin Liew (2011) Deforestation rates in insular Southeast Asia between 2000 and 2010. Global Change Biology 17: 2261–2270.

Rheindt, F. E. (2010) New biogeographical records for the avifauna of Taliabu (Sula Islands, Indonesia), with preliminary documentation of two previously undiscovered taxa. Bulletin of the British Ornithologists’ Club 130(1): 33–51.

Stones, A. J., Lucking, R. S., Davidson, P. J. and Wahyu Raharjaningtrah (1997) Checklist of the birds of the Sula Islands (1991), with particular reference to Taliabu Island. Kukila 9: 37–55.

Tobias, J. A., Seddon, N., Spottiswoode, C. N., Pilgrim, J. D., Fishpool, L. D. C. and Collar, N. J. (2010) Quantitative criteria for species delimitation. Ibis 152: 724–746.

Related posts:

  1. Archived 2014 discussion: Moluccan Scops-owl (Otus magicus) is being split: list O. tempestatis as Vulnerable?
  2. Archived 2014 discussion: Philippine Scops-owl (Otus megalotis) is being split: list O. nigrorum as Vulnerable and O. megalotis and O. everetti as Near Threatened?
  3. Archived 2014 discussion: Biak Scops-owl (Otus beccarii): downlist to Vulnerable or Near Threatened?
  4. Archived 2014 discussion: Crested Serpent-eagle (Spilornis cheela) is being split: list S. minimus as Near Threatened? (Discussion now being closed)
  5. Archived 2010-2011 topics: Sula Megapode (Megapodius bernsteinii): uplist to Vulnerable or Endangered?
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2 Responses to Archived 2014 discussion: Sulawesi Scops-owl (Otus manadensis) is being split: list O. mendeni and O. sulaensis as Vulnerable?

  1. Andy Symes says:

    Preliminary proposals

    Based on available information, our preliminary proposals for the 2014 Red List would be to treat:

    Sulawesi Scops-owl Otus manadensis as Least Concern
    Banggai Scops-owl Otus mendeni as Vulnerable under criterion C2a(ii)
    Sula Scops-owl Otus sulaensis as Near Threatened, nearly meeting the threshold for classification as Vulnerable under criterion C1

    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.

  2. Andy Symes says:

    Recommended categorisations to be put forward to IUCN

    Following further review, there have been no changes to our preliminary proposals for the 2014 Red List status of these species.

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

Comments are closed.