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.
African Scops-owl Otus senegalensis is being split into O. senegalensis, O. pamelae, O. socotranus and O. feae, following the application of criteria set out by Tobias et al. (2010) and consideration of recent evidence (Pons et al. 2013).
Prior to this taxonomic change, O. senegalensis (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. feae is endemic to Annobón Island (Pagalu), Equatorial Guinea (König and Weick 2008). It was reported to be abundant in dense forest at 400-500 m by Fea in 1902, but may not have been recorded since the mid-20th century (Harrison 1990, Jones and Tye 2006).
Forest on Annobón is threatened by clearance for agriculture and development, including plantations of bananas, jackfruit, oil-palm and mango (Harrison 1990, Jones and Tye 2006). However, changes to natural habitats have been reported to be much less extensive than on São Tomé and Príncipe (Harrison 1990), perhaps influenced by the relatively stable human population (Jones and Tye 2006). Former plantations of cocoa and coffee on Annobón have been abandoned, and are being colonised by kapok Ceiba pentandra, oil-palm, mango and tamarind (Jones and Tye 2006).
The species’s tolerance of habitat degradation and introduced tree species is not known, but it is precautionarily assumed to rely on undisturbed native forest, especially given that it has been described as rare in thick forest (Basilio 1957 in Harrison 1990). Following this reasoning, it is suggested that the species qualifies as Endangered or Critically Endangered under criterion C2a(ii), on the basis that its population numbers fewer than 2,500 mature individuals, and perhaps fewer than 250 mature individuals, and is inferred to be in on-going decline owing to habitat loss and alteration.
O. socotranus is endemic to Socotra Island, Yemen, where it is resident in semi-desert with scattered bushes and trees, generally in rocky landscapes (König and Weick 2008, Jennings 2010). It seems to prefer tree-lined wadis, especially with dense stands of palms; however, its habitat requirements have not been fully studied (Jennings 2010). It is characterised as generally not common, but locally numerous. Where suitable habitat is present, the species may occur close to human habitations. There is no information to suggest competition with other species for nesting sites (Jennings 2010).
Various surveys carried out between 1999 and 2007 indicate a population of c.300 pairs, although it could be more numerous (Jennings 2010). There is no historic information available to indicate any changes in its status or population (Jennings 2010). On the basis of this information, the species is assumed to have a population of fewer than 1,000 mature individuals, which is likely to be stable, therefore qualifying it as Vulnerable under criterion D.
O. senegalensis (as defined following the taxonomic change) is widespread in sub-Saharan Africa, where it occupies a variety of wooded habitats, whilst O. pamelae occurs in semi-desert in the Arabian Peninsula, in Saudi Arabia, Yemen, Oman and United Arab Emirates (König and Weick 2008). O. pamelae is locally common, and where it does occur it is probably the most abundant owl species (Jennings 2010).
Both O. senegalensis and O. pamelae are thought likely to qualify as being of Least Concern, on the basis that they do not approach the thresholds for Vulnerable under any of the IUCN Red List criteria.
Comments on these suggested categories are invited and further information would be welcomed.
Harrison, M. J. S. (1990) A recent survey of the birds of Pagalu (Annobon). Malimbus 11: 135–143.
Jennings, M. C. (2010) Atlas of the breeding birds of Arabia. Fauna of Arabia 25. Frankfurt, Germany and Riyadh, Saudi Arabia: Senckenberg Gesellschaft für Naturforschung and King Abdulaziz City for Science and Technology.
Jones, P. and Tye, A. (2006) The birds of São Tome & Príncipe, with Annobón islands of the Gulf of Guinea: An annotated checklist. BOU Checklist No. 22. Oxford, UK: British Ornithologists’ Union and British Ornithologists’ Club.
König, C. and Weick, F. (2008) Owls of the world. Second edition. London: Christopher Helm.
Pons, J.-M., Kirwan, G., Porter, R. and Fuchs, J. (2013) A reappraisal of the systematic affinities of Socotran, Arabian and East African scops owls (Otus, Strigidae) using a combination of molecular, biometric and acoustic data. Ibis, doi: 10.1111/ibi.12041
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.