The distribution, specimens and status of Chestnut Owlet Glaucidium (capense) castaneum and Albertine Owlet G. (c.) albertinum

Summary. Chestnut Owlet Glaucidium (capense) castaneum and Albertine Owlet G. (c.) albertinum are poorly known members of the African Barred Owlet Glaucidium capense complex, confined to the Albertine Rift of East Africa. Recent taxonomic treatments have seen them variously considered as subspecies of capense, as separate monotypic species or, in the case of castaneum, a polytypic species. A paucity of museum material and field knowledge of each, combined with oversight and misinterpretation of some primary literature, has contributed to this uncertainty. This study reassesses their status and corrects numerous errors, misunderstandings and contradictions concerning specimen material, distribution, morphology and voice. Only four specimens of castaneum are known, there are no documented observations of the bird in life and no acoustic recordings. There are seven specimens of albertinum in collections. No field sightings have ever been documented but several recordings attributed to albertinum exist. Despite its close similarity to the voice of capense, there is no published evidence that albertinum reacts to playback, unlike the remaining taxa of the complex. I conclude that castaneum is a modestly distinct subspecies of capense. In contrast, albertinum, which differs conspicuously from the others in the complex by its disproportionately short tail, and which may be parapatric with castaneum, merits treatment as a species.

[1]  J. S. Marks,et al.  African Barred Owlet (Glaucidium capense) , 2020 .

[2]  Matthew J. Miller,et al.  HBW and BirdLife International Illustrated Checklist of the Birds of the World Volume 2: Passerines Josep del Hoyo, Nigel J. Collar. 2016. Lynx Edicions, Barcelona, 1013 pages, hundreds of color plates. ISBN 9788496553989. $269 (Hardcover). , 2017 .

[3]  Jared D. Wolfe,et al.  Strigidae (Typical Owls) , 2017 .

[4]  Durban Museum Novitates.  MISCELLANEOUS TAXONOMIC NOTES ON AFRICAN BIRDS , 2017 .

[5]  S. T. Osinubi.  The Birds of Ghana: an Atlas and Handbook , 2016 .

[6]  J. Buchanan.  Owls of the World: A Photographic Guide , 2015 .

[7]  Rq Skeen.  A review of birds in Uganda: records updating the Uganda Atlas and notes on species unrecorded since 1980 , 2014 .

[8]  Hui-Yun Tseng,et al.  Colour Morphs in the Collared Pygmy Owl Glaucidium brodiei are Age-Related, not a Polymorphism , 2014 .

[9]  R. B. Payne.  Roberts Geographic Variation of Southern African Birds , 2013 .

[10]  R. Cheke.  African Barred Owlet Glaucidium capense new to Togo , 2008 .

[11]  J. Dunning,et al.  CRC Handbook of Avian Body Masses , 2007 .

[12]  P. Gregory.  THE BIRD ATLAS OF UGANDA , 2007 .

[13]  J. Clements.  Clements checklist of birds of the world , 2007 .

[14]  Tom De Bruyn,et al.  The Democratic Republic of Congo , 2006 .

[15]  Friedhelm Weick,et al.  Owls (Strigiformes): Annotated and Illustrated Checklist , 2006 .

[16]  A. Kratter,et al.  The Howard and Moore Complete Checklist of the Birds of the World , 2005 .

[17]  A. Kemp,et al.  SASOL Birds of Prey of Africa and Its Islands , 2005 .

[18]  P. Ryan,et al.  Birds of Africa, south of the Sahara , 2004 .

[19]  F. Huettmann.  "Important Bird Areas in Africa and Associated Islands: Priority Sites for Conservation" by L. D. C. Fishpool and M. I. Evans. 2001. [book review] , 2003 .

[20]  Barry Meatyard,et al.  Threatened Birds of the World , 2001 .

[21]  J. D. Rossouw,et al.  New records of uncommon and poorly known species for Ugandan National Parks and Forest Reserves , 2001 .

[22]  A. Hughes.  Endemic Bird Areas of the World: Priorities for Biodiversity Conservation. Alison J. Stattersfield , Michael J. Crosby , Adrian J. Long , David C. Wege , 2000 .

[23]  R. Dowsett.  New species and amendments to the avifauna of Cameroon , 2000 .

[24]  J. Hart,et al.  The Itombwe Massif, Democratic Republic of Congo: biological surveys and conservation, with an emphasis on Grauer's gorilla and birds endemic to the Albertine Rift , 1999, Oryx.

[25]  A. Stattersfield,et al.  Endemic Bird Areas of the World: Priorities for Biodiversity Conservation , 1998 .

[26]  Alison J. Stattersfield,et al.  Birds to watch 2 : the world list of threatened birds , 1996 .

[27]  E. Mayr,et al.  New species of birds described from 1981 to 1990 , 1992 .

[28]  A. Prigogine.  Statut de quelques chevechettes africaines et description d'une nouvelle race de Glaucidium scheffleri du Zaïre , 1985 .

[29]  S. Stuart,et al.  Threatened birds of Africa and related islands , 1985 .

[30]  A. Prigogine.  Un nouveau Glaucidium de l'Afrique centrale (Aves, Strigidae) , 1983 .

[31]  J. Williams,et al.  A field guide to the birds of East Africa , 1980 .

[32]  G. Morel,et al.  Les oiseaux de l'Ouest africain , 1979 .

[33]  D. Snow.  An atlas of speciation in African non-passerine birds , 1978 .

[34]  H. Friedmann,et al.  The birds of the lowlands of Bwamba, Toro Province, Uganda , 1971, Contributions in science.

[35]  C. M. White..  A revised check list of African non-passerine birds , 1965 .

[36]  P. A. Clancey..  Miscellaneous taxonomic notes on African birds X , 1958 .

[37]  Robert W. Storer.  Exploration du Parc National de l'Upemba, Fascicule 19, Oiseaux René Verheyen , 1953 .

[38]  J. Chapin.  The birds of the Belgian Congo , 1932 .

[39]  A. Reichenow.  Die Vögel Afrikas, von Ant. Reichenow ... , 1900 .

[40]  R. L..  The Birds of Africa , 1900, Nature.