“Danger! Humans!” The Elephants Cried.
Elephants Have a Very Sophisticated Vocabulary.
Elephant alarm calls are so sophisticated that they can communicate who or what the threat is. In this study the researchers analysed the acoustic properties of each type of alarm call and discovered that the elephants were able to tell their herd whether the threat was from humans or bees. A human would not be able to detect this difference because the calls include distinctive features at a low frequency inaudible to the human ear.
An earlier study had shown that when elephants hear the sound of disturbed bees they make a distinct alarm call to warn other elephants of this threat.
The research was conducted on wild elephants in Kenya by Oxford University, Save the Elephants and Disney’s Animal Kingdom. The elephant species was Loxodonta africana.
The purpose of this research was to discover whether elephant alarm calls:
• identify the specific type of threat, in this case humans or bees;
• indicate the level of urgency the threat poses;
• result in behaviour based on the type of threat and the level of urgency.
A recording of the voices of male Samburu tribesmen was played to resting elephants and their behaviour and vocal responses were recorded. The vocalisations were played to another group of resting elephants to see if their reaction would be the same. It was. Both groups became vigilant and ran away making a low rumbling call.
Humans pose the greatest threat to elephants. This threat includes poaching for ivory, destruction of their habitat and conflict over water and other resources. In the wild elephants have few predators, although lions will attack elephant calves.
Amazingly elephants have learnt which tribes of humans in Kenya pose the greatest threat. They can distinguish between Samburu herdsmen, Masaai herdsmen and Kamba farmers, as earlier studies have shown. The Masaai will kill elephants. The elephants know this and their alarm calls warn of greater danger when they smell or see Masaai, than when they smell or see the Kamba, who pose less of a threat. They recognise the voices of Samburu herdsmen and, impressively, were also able to decide how great the threat was from the Samburu tribesman in different situations. Their alarm calls reflected this: mostly they would just rumble, but when they perceived a greater threat from the Samburu they would roar and trumpet as well.
The Samburu are pastoralists in northern Kenya. Their cultural beliefs mean that traditionally they have not hunted elephants for ivory or meat. However, as human populations grow the Samburu come into conflict with elephants over resources such as the watering hole. Chance encounters in the bush can also be deadly for elephants. So these days the Samburu do pose a threat to the elephants.
Elephants produce a number of alarm calls in response to threats from predators, including rumbles, roars and trumpets. The most frequent type of call is the rumble. At the highest level of perceived threat the rumble includes roars and trumpets.
The response of the elephants to the bees was compared with their response to the Samburu male voices. In both cases the elephants showed heightened vigilance, made warning calls and ran from the threat.
One behaviour that was specific to the alarm call signifying bees, and which did not take place when the elephants heard the alarm call for humans, was an increase in headshaking. The elephants shook their heads to ward off the bees, dislodge any that were already on their heads and prevent bee stings.
To find out if the level of threat was communicated by the alarm calls the rumbles, roars and trumpets were acoustically modified to reflect three levels of threat:
• Low rumble with roars and trumpets reflecting the highest level of alarm. This resulted in the most extreme reaction from the elephants.
• The same low rumble but with the roars and trumpets removed. This was the most typical response to the sound of Samburu voices, and elicited a similar response to that of the threat of bees.
• Rumble which sounded like the non-alarm rumbles elephants make. The elephants’ response was to move half the distance compared with the level 2 alarm. As a control, the recordings included a section of “white noise” which elicited the lowest level of response from the elephants.
On hearing the calls the elephants became vigilant. They did this by: “smelling” , when an elephant raises his trunk into the air or stretches it out in front of his face, horizontally; “scanning” for danger, with their ears held out; “head-up” when the elephant lifts its head with its ears held out and holds this position for more than 2 seconds. When these are all displayed at the same time they are known as “vigilance” behaviours.
Elephants have remarkable vocal abilities. They can manipulate their mouth, tongue and trunk to shape and alter the sounds of their rumbles and thus make different alarm calls which identify the type of threat and also the level of threat. The difference between the alarm rumble warning of humans and alarm rumble warning of bees can be compared to the effect of a person changing a vowel in a word, for example “poo” and “pee”. This is similar to the way humans vocalise. Elephants can produce rumbles through both their mouth and their trunk. The alarm rumbles are produced through their trunk.
Impressively, elephants can learn to imitate the sounds of the environment and the calls of other species, including humans and other elephant species. They have also worked out in which places they are most at danger, and they avoid these.
Elephant communication is complex and sophisticated; further research is being done in this exciting field.
The ultimate purpose of this study is to safeguard the elephant population by learning how to avoid conflict between humans and elephants, while at the same time protecting the livelihoods of the local population.