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Title: The low frequency vocal communication for a herd of African elephants (Loxodonta africana) in the Okavango Delta, Botswana
Author: Bowles, Graham Robert
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2012
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Since the 1980s much research has focused on the long-distance properties of elephant rumble calls. Few studies have been able to study the short-distance, intra-herd calling 01 elephants. Such understanding is imperative to the future study of their complex social behaviour. 'used a collar mounted audio and GPS data acquisition system on a captive herd of elephants based in the Okavango Delta, Botswana, to help resolve some of the logistical issues that have prevented such research in the past. My results showed that the best accuracies for predicting individual identity were achieved when using source frequency, modulation, and filter features of the call. However, comparable accuracies were still achieved when the modulation features were removed. This study also showed that similarities in calling behaviour were more influenced by social affiliations than size or age. My results also showed a framework for sub-categorising rumble calls based on their position of peak energy, degree of modulation, modulation shape, duration, and fundamental frequency. I successfully applied this method to published rumble calls, which showed that it was not limited to calls from the study herd and that such differences may be used to encode referential and motivational information. This is also the first study that measured how elephant calling behaviour is affected by seasonal and daily variations in conditions. While this study showed few changes, such aspects are important to consider in future research on elephant vocalisations. My results also showed that the contact call is not structurally defined and that call structure is more likely to be influenced by adaptations to resist sound attenuation and levels of excitement. In conclusion, I discuss how these results have improved our current understanding of low frequency calls, showing the cues receivers might use to determine various aspects about the sender and how elephants might adapt their calling to external influences. I also highlight areas of future work and discuss the advantages of the techniques used to over come some common problems faced in gathering such data and how these could be improved .
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available