Determining the suitability of using eye wrinkle patterns for the accurate identification of individual black rhinos

Abstract

Photograhic identification is used to identify individual black rhinos (Diceros bicornis) with the distinguishing features of sex, the size and shape of the anterior and posterior horns, peculiarities of the ears, the pattern of wrinkle contours on the snout, prominent scars and sores on the body, the state of the tail, body size including the size of a calf in relation to the mother and skin folds. Eye wrinkle patterns have received little attention but were found to be useful when separating a large number of photographs of 19 captive rhinos particularly for distinguishing individual sub-adults where other features such as horn length and shape were very similar. Each rhino was found to have unique eye wrinkle patterns which remained consistent when the eyes were open or closed. By developing and applying a series of tests, judgement errors that occur when reviewing eye wrinkle photographs were determined and are reported. Results show that individual black rhinos can be accurately identified from suitable photographs but, even for the best of thejudges, using eye wrinkles alone to identify individual rhinos was not completely reliable.