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We continue our Researcher of the Month (RotM) series, with an interview with Professor Michael Garstang, Distinguished Investigator and Research Professor at the Department of Environmental Sciences at the University of Virgina. Professor Garstang is also associated with a Simpsons Weather Associates, a private environmental research company and recently published a paper in PLoS One about response of elephants to seasonal changes.
CTS: For the benefit of our readers, could you please tell us more about your findings in the recent study.
MG: Elephants, both in legend and in scientific observations, are said to respond to the onset of rains after a protracted period of dry conditions typical of their subtropical dry savanna habitat. In previous research (Michael Kelley and Michael Garstang published in “Animals” (2013)), we demonstrated that elephants are able to hear distant thunderstorms as far away as a few hundred kilometers. Our research effort was to see if we could demonstrate that elephants did respond to the early rains and did so by a change in their movement patterns perhaps even triggering their migrations.
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| SODAR (SOnic Detection And Ranging) antenna being unboxed at the site of the study. The antenna is used to determine the sounds used and detected by the elephants. It helps researchers determine what the elephants can and cannot hear. Image copyright: Mike Garstrang |
CTS: When we say movement is observed in elephants, do we see this movement towards the rainfall region of away from the region?
MG: We found that elephants in western Namibia, a very dry and rugged region known as the Kunene, did in fact change their pattern of movement from those typical of the dry season to a more extended pattern once the rains began. These rains were as far away as 300 km from the elephant’s location with no rain falling at the elephant’s location. However, they did not move towards the rain systems but extended their daily movements out of the river channels and into more rugged topography.
CTS: What might be reasons for this?
MG: They may have learnt over time that they could now extend their territory encompassing the new growth of the wet season away from the permanent water sources they depended upon during the dry season. They seem to anticipate the rain which is yet to arrive.
CTS: Your study included a set of 14 elephants. Could we consider this to a good representation for entire species of L.africana elephants?
MG: The elephants of the Kunene may still be highly stressed and even residually suffering from the traumatic civil wars which swept over them in the latter part of the 20th century. They suffered from severe poaching with drastic reduction in numbers so that the elephants we studied were still in small family units (perhaps only 3 or 4 individuals not always closely related) and not typical of the complex multiple levels of association typical in the rest of Africa.
Our study may thus be of value in demonstrating the ability and manner in which elephants cope with and recover from such traumatic events.
CTS: You are also associated with Simpsons Weather Associates (SWA). How does data from this study help SWA in its work?
MG: SWA conducts research into environmental problems. It has a long history (40 + years) of
involvement in research in the tropics and in elephant habitat. You can find more about activities of SWA at http://www.swa.com/
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| Tethered balloon that carries equipment to accurately measure temperature and atmospheric density (and a giraffe in the background). Image copyright: Mike Garstang |
CTS: How will findings from the study help in conservation of these elephants?
MG: Our findings have shown that a population subjected to severe disruption in an extreme climate responds by limiting movements under dry conditions but expanding into wider territory prior to the onset of rains. While unable in this study to demonstrate that elephants use infrasound to detect the occurrence of rainfall at locations more than 100 km away, the evidence presented suggests that elephants can detect these rain events and recognize them as the precursors of rainfall in their region.
We believe that a wide range of sound plays a crucial role in the lives of elephants. These findings move us forward in the understanding of the potential roles that biotic and abiotic sound plays in the lives of elephants.
CTS: How will research work proceed further from here?
MG:We will continue to analyze existing observations of elephant movements in western Namibia as well as explore other possible signals that elephants might be able to detect. Since this work is in progress and results are uncertain, speculation about possible findings is premature. From experience we know that early hypotheses are often wrong and objectives are continually revised and sharpened as work progresses.
References:
Garstang, M., Davis, R., Leggett, K., Frauenfeld, O., Greco, S., Zipser, E., & Peterson, M. (2014). Response of African Elephants (Loxodonta africana) to Seasonal Changes in Rainfall PLoS ONE, 9 (10) DOI: 10.1371/journal.pone.0108736
Kelley, M., & Garstang, M. (2013). On the Possible Detection of Lightning Storms by Elephants Animals, 3 (2), 349-355 DOI: 10.3390/ani3020349
