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Research / Discovery

Researcher uses sound to make wildlife discoveries

April 5, 2014

New research has found that elephants are able to identify humans that pose a threat to them by distinguishing ethnicity, gender, and age from acoustic cues in human voices.

On the move - elephants responding to audio playback.Graeme Shannon, now a post-doctoral behavioural ecologist at Colorado State University’s Warner College of Natural Resources, is a joint lead author on the research and has been making international headlines for his innovative work using acoustic research methods.

Elephants’ understanding of language

Shannon and Karen McComb at the University of Sussex studied family groups of African elephants in Amboseli National Park, Kenya. They used camouflaged loudspeakers to play sound recordings of the voices of two different human ethnic groups known to them: the Maasai, who, periodically come into conflict with elephants over access to water and grazing for their cattle, and the Kamba, whose more agricultural lifestyle poses less of a threat to elephants.

The results showed that elephants were more likely to demonstrate defensive behaviour, such as bunching together and investigative smelling, in response to male Maasai voices than male Kamba voices. Their behaviour An elephant smells the air after hearing voice recordings.was also less defensive in response to voices of Maasai women and boys, indicating that elephants can use subtle acoustic cues associated with sex and age when assessing the threat posed by different human groups.

The ability to discriminate real from apparent threat, particularly in the case of human predators that differ in relatively subtle cues, has important impacts on the capability of elephants to avoid stress and danger.

“The human language is rich in acoustic cues. The ability to distinguish between Maasai and Kamba men delivering the same phrase in their own language suggests that elephants can discriminate between different languages,” said Shannon. “This sophisticated skill would have to be learned through development and gives elephants an additional advantage in serving as an effective early warning system against predators.”

Elephants can suffer from PTSD

In 2013, Shannon and McComb published another study using elephant vocalizations that showed African elephants can suffer from conditions similar to post-traumatic stress disorder common in combat veterans.

Elephants grazing in Amboseli National Park.The study used novel playback experiments with life-like sound projections from custom-built loudspeakers to study the long-term social disruption of mass culling on elephant populations. The team played a range of elephant contact calls – low frequency vocalisations –to target family groups to simulate different levels of social threat. African elephants that had experienced separation from family members and translocation during culling operations decades earlier performed poorly on systematic tests of their social knowledge. They failed to distinguish between callers on the basis of social familiarity or different scales of social dominance, in sharp contrast to undisturbed populations.

The study provided the first systematic evidence that elephant’s fundamental social skills and decision-making abilities may be significantly impaired by severe human disruption, such as culling and poaching. The findings highlighted the potential long-term negative consequences of acute social dsruption in cognitively advanced species that live in close-knit kin-based societies, such as elephants, primates and cetaceans.

Wildlife Sound Research at CSU

Shannon is conducting isolated sound playback experiments in remote areas with recordings of rush-hour traffic to determine how prairie dog colonies are impacted by transportation noise.Shannon has worked with elephants for more than 12 years, and came to the United States from Britain to work with a research team including CSU Professor George Wittemyer, a leading elephant conservation biologist and professor in CSU’s Department of Fish, Wildlife, and Conservation Biology.

“Acoustic data is an innovative and growing field for conservation research with limitless potential for new discovery,” said Wittemyer. “We are excited to have Dr. Shannon’s experience with anthropogenic noise studies at CSU.”

Shannon has worked with sound experiments since 2006 and is continuing advancements in the use of acoustic experiments in wildlife and conservation biology studies. He is part of an inter-disciplinary team in CSU’s Warner College working with the National Park Service’s Natural Sounds and Night Skies Division - who are analysing acoustical data from parks to help inform NPS studies and management decisions. He is also taking his elephant research methods and applying them to a much smaller mammal native to Colorado – the prairie dog.

Shannon is conducting isolated sound playback experiments in remote areas with recordings of rush-hour traffic to determine how prairie dog colonies are impacted by transportation noise. Initial findings suggest that traffic sounds significantly altered prairie dog aboveground activity, foraging and vigilance behaviour. While smaller and perhaps less iconic than elephants, Shannon notes that prairie dogs are highly intelligent and social species and their colony structure makes them ideal behaviour research subjects.

Sound's influence on animal behavior

“Sound has an extremely pervasive influence on animal behavior, and so acoustic studies have a very exciting and important opportunity to really deepen our understanding of wildlife biology and responses of these species to human disturbance,” said Shannon. “This is a field that has huge opportunity for growth and can be a powerful tool to advance natural resources management policy.”

Shannon hopes to continue his research in the U.S. and sees great potential to make new discoveries on issues such as the acoustic impacts of traffic noise on wildlife or the effects of urbanization and human activity on native rangeland species. Shannon earned his undergraduate degree at the University of York, his M.Sc. in conservation biology at University of Kent, and his Ph.D. at University of KwaZulu-Natal in South Africa.