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