Vocal identification of individual African Wood Owls Strix woodfordii: a technique to monitor long-term adult turnover and residency |
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Authors: | Wayne Delport ,Alan C. Kemp,& J. Willem H. Ferguson |
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Affiliation: | Department of Zoology and Entomology, University of Pretoria, 0002, Pretoria, South Africa;Transvaal Museum, Northern Flagship Institution, PO Box 413, 0001, Pretoria, South Africa |
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Abstract: | The hoot-calls of Wood Owls Strix woodfordii , recorded in the Kruger National Park, South Africa, from 1986 to 1998, are sufficiently different to distinguish individuals. Thirteen hoot-call variables, measured from recordings over this period, show that male and female Wood Owls have such temporal stability that these calls can be used reliably as a long-term census technique. manova , based on ordinations from principal component analysis, was used to identify individuals statistically between sampling periods. A forward stepwise discriminant function analysis achieved 100% classification success of individual male ( n = 3) and female ( n = 4) owls from a single sampling period. For all the individuals recorded over the whole study period we achieved a classification success of 80.9% ( n = 9) for male hoot calls and of 96.3% ( n = 13) for female calls. We found mean occupation periods of 82.25 and 65 months and annual turnover rates of 19.3% and 13.65% for males and females, respectively. Our survey, using vocalizations, is unique since we use data collected over a 12-year period to derive estimates of population turnover in Wood Owls, and consider what questions can be addressed in similar studies. |
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