Eavesdropping on Elephants

I’ve made it no secret that forest elephants are hidden giants, concealed by the vast canopy cover of Central African forests. To study them, one has to get creative. For me, it was collecting dung. For Dr. Peter Wrege, it’s sound. Wrege’s background is cemented in bird behavior, but for the past decade he has been heading the Elephant Listening Project, an organization to study and protect elephants using their sounds. I was able to see Wrege speak recently and will share with you some of the amazing work of the Elephant Listening Project.

Forest elephants I was able to observe during my Ph.D. research in Lope National Park, Gabon.

You may be thinking that elephants only make one sound, their trumpet, and that most of the time they are quiet. They are actually quite chatty, but most of the calls they make actually sound prehistoric and are more difficult for us to hear. You know the scene in Jurassic Park when we first see the T. rex  and it lets out a bone-chilling, subtle growl? That growl right before the roar is what a forest elephant sounds like. These “growls” are called rumbles and are mostly infrasonic (below our level of hearing). They were first discovered by Dr. Katy Payne, who studied whales (another very large mammal). She could actually feel them when she was at a zoo’s elephant exhibit, as two elephants were communicating to each other through a wall. These calls travel far and wide in the wild, at least two kilometers, which was the maximum extent that the sound recorders would play in the field.

Forest elephant rumbles surprisingly sound a lot like the T. rex growl in Jurassic Park. Image from io9. 

Wrege played a video of two elephants standing next to each other and both facing forward, constantly overlapping in rumbles. What were they saying? A greeting rumble to each other. Elephants can recognize each other from their rumbles, which is especially beneficial when you live in a forest. Just like we can’t see elephants in the forest, they can’t see each other well and it’s hypothesized that these infrasonic vocalizations that travel far have evolved as a means for elephant groups to communicate even when apart. To further demonstrate this, he played videos and vocalizations from two elephants at a natural forest clearing, where you can see the elephants. During the day, when their eyesight is effective, the elephants were not vocalizing much, but watching each other. But during the night (Wrege could see using a thermal camera), the elephant vocalized much more and were touching each other because they couldn’t see.

Thermal images show elephant activity at night. Image from PRI.

While most of us are interested in decoding the elephant language (“elephant dictionary”), this is actually really hard to do. In order to understand specific rumbles, you need to record the behavior with it. This is possible in large clearings like Dzanga Bai, where Dr. Andrea Turkalo, his collaborator, has studied forest elephant for over two decades, and where you can see the elephants well. But sometimes the behaviors are so rich, it can be difficult to separate out specific movements with rumbles. You also need many repetitions of the same types of behaviors and vocalizations to ensure you know what it means. At Dzanga, many elephants visit the bai (at least around 40 a day), so you not only have a lot of videos and sound recordings to go through, but also knowing which individuals to focus on recording can be difficult and important behaviors may be missed. Some elephants even call from the forest interior close to the bai, but out of view for behavioral observations.

Unfortunately decoding elephant language can not be a priority because of the state of the forest elephant. Effort spent to decode a language will be useless if we lose the entire species to ivory poaching. Rather, the Elephant Listening project is focusing research on filling in the very large gaps on where poachers are and when poaching occurs. Wrege and his teams hang sound recorders from trees, which allow him to figure out hotspots of elephant activity (more elephant calls likely equals more elephants). This provides a much faster inventory of how elephants use the landscape than traditional dung surveys, which can be slow and expensive. These devices not only record elephants, but also gunshots, which also shows hotspots for poaching. Wrege even played a recording of gunshots, with the familiar rumbler heard after it, signifying a majestic individual (or likely family) was shot and died. Wrege recognized this is extremely sad, but important for us all to witness, as we are losing forest elephants at an unprecedented rate just for ivory statues and trinkets.

Wrege hopes to scale up this effort of monitoring using smaller devices that can be dropped over large areas from a plane to cover a much larger landscape. To give you an idea of the scope of the problem, in an area roughly the size of Connecticut, there is only one village, almost no roads, and no cell phone towers. This means that it’s really hard to get both in and out to know what elephants are there and what poaching is going on. Minkebe National Park (a protected area) borders this area and used to have one of the densest forest elephant populations, but by 2011 was decimated. If recording devices were used in the monitoring process, they could have informed park managers much faster and potentially saved elephant lives.

The only way to truly solve this problem though is by changing the demand side. When asked what one can do to help save elephants, Wrege responded that its most important to just tell someone. It’s only when we spread the knowledge that elephants do not shed their tusks, are not found dead and the tusks collected, and that they are actively killed and at an unsustainable rate for their tusks, that this problem will start to reverse. Only then, can we decode the mysteries of their complex language.

 

 

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