Field identification of individual White-headed Vultures Trigonoceps occipitalis using plumage patterns - an information theoretic approach
2012
Murn, Campbell
Capsule Individual White-headed Vultures can be reliably identified by the pattern in their median wing coverts.Aims To highlight the distinctiveness of the median wing covert pattern in White-headed Vultures and demonstrate the reliably high information content contained in this pattern.Methods Photographs of 30 wild White-headed Vultures were image-processed and overlaid with an analysis grid. An information theoretic approach was used to determine the probability of a specific median wing covert pattern recurring in the population. This probability determines the information content of each pattern.Results The information content of median wing covert patterns is high (median content 23.54 bits) and the probability of pattern recurrence in a population of 10 000 birds is low (P = 2.04 × 10⁻³). The likelihood of the pattern changing over time is low.Conclusions White-headed Vultures show variation in their median wing covert pattern that is sufficient for birds to be individually identifiable in the field. This non-invasive identification technique is reliable and is suitable for cataloguing local and regional populations of adult White-headed Vultures, thus facilitating mark–recapture studies or other studies that require identification of individuals.
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