In this paper we assess the applicability to the extraction of conservation information of three commonly used methods of examining the individuality of acoustic signals: qualitative assessment, spectrographic cross-correlation and discriminant function analysis. We tested the ability of human observers, with different levels of training, to sort and match spectrograms of bittern and fantail warbler vocalisations. This simulated a census and monitoring situation. We found that training had little effect on accuracy and high inter-individual variation made generalizations difficult. Cross- correlation provides an objective measure of similarity but was shown to be sensitive to background noise and the signal structure being compared. Discriminant function analysis is a powerful descriptor of individuality and functions well when developing predictive tools. However it should not be used to count a population and its use is constrained to re-identification in populations of known size.
Individuality, cross-correlation, qualitative analysis, discriminant function, conservation.