Sexual dimorphism of four owl species in South Africa

  • Tahla M Ansara-Ross Department of Zoology, University of Johannesburg, Auckland Park Campus, PO Box 524, Auckland Park 2006, South Africa
  • Victor Wepener Department of Zoology, University of Johannesburg, Auckland Park Campus, PO Box 524, Auckland Park 2006, South Africa
  • Gerhard H Verdoorn Department of Zoology, University of Johannesburg, Auckland Park Campus, PO Box 524, Auckland Park 2006, South Africa; BirdLife South Africa, PO Box 515, Randburg 2125, South Africa
  • Mathew J Ross Department of Zoology, University of Johannesburg, Auckland Park Campus, PO Box 524, Auckland Park 2006, South Africa­

Abstract

Sexual dimorphism was studied in four South African owl species (African Grass-Owl Tyto capensis, Barn Owl T. alba, Marsh Owl Asio capensis and Spotted Eagle-Owl Bubo africanus) by examining specimens of intact owl carcasses found killed by vehicles along a national road in Gauteng province, South Africa. Females were significantly heavier and larger than males for most species. The body mass and length of T. capensis, and body mass and tail length of A. capensis, were significantly different, with females being larger than males. Body, wing, tail and tarsus length for T. alba males were significantly different to females. For B. africanus, only tarsus length was found to be significantly different among genders. These findings were reiterated further when applying a dimorphism index to the same morphometric measurements. This study contributes to morphometrics distinguishing the sexes of the four southern African owl species, especially T. capensis, which has a Vulnerable IUCN status.

Ostrich 2008, 79(1): 83–86
Published
2008-05-13
Section
Articles

Journal Identifiers


eISSN: 1727-947X
print ISSN: 0030-6525