Vocal stress associated with a translocation of a family herd of African elephants (<i>Loxodonta africana</i>) in the Kruger National Park, South Africa

Abstract

We used vocal indicators to examine the effect of a translocation of an African elephant&#13;\nfamily herd within the Kruger National Park (KNP). These animals were moved 300&#13;\nkm from their home range, but returned unaided to this range within 23 days. We found&#13;\nthat translocation resulted in a change in the mean fundamental frequency of lowfrequency&#13;\nelephant vocalizations, known as rumbles. The rumbles increased&#13;\nsignificantly in pitch compared to pre-translocation levels during the 23 days the&#13;\nanimals spent outside their normal home range. Mean fundamental frequency returned&#13;\nclose to pre-translocation level by the time the animals had navigated their way back to&#13;\ntheir previous home range. Raised pitch is known to be an indicator of stress in humans&#13;\nand other animals. The observed acoustic results are consistent with a physiological&#13;\nmeasure of stress, faecal glucocorticoid metabolite (FGM) levels, which were&#13;\nmonitored of the same animals during the study and have already been reported&#13;\nelsewere. This, to our knowledge, is the first report of prolonged monitoring of vocal&#13;\nstress response in free-ranging animals. Measuring behavioural responses, such as&#13;\nvocalizations, may provide an objective non-invasive method for assessing stress. This&#13;\ncould help in determining the effects that particular management actions might have on&#13;\nelephants.