Elephant Research

Old and new technology – each has an important role to play

Basic research, and applying what we learn directly to enhance conservation efforts, is a primary focus of the Elephant Listening Project. About equal effort is targeted at gathering new data from the forests of Central Africa, pushing the boundaries of how we can use acoustic monitoring to achieve conservation goals, and building capacity in Central Africa to ensure sustainable conservation into the future.

While the use of innovative technology is a key part of what we do, good old basic observational studies also play a key role. Linking specific calls to interactions requires careful (and long) observation. At the same time, we strive to teach local assistants and researchers how to use the technology, building capacity in the next generation of conservationists.

We have no “home base,” but rather work with other conservation NGOs (Wildlife Conservation Society, World Wildlife Fund, the Korup Research and Conservation Society) to run projects where they can do the most good. We have collected sounds from the forest at 32 different locations, many monitored continuously for years. We have the world’s largest archive of sounds from Central Africa– more than 900,000 hours. Our focus now is on a large study in northern Congo generating the first ever glimpse into how forest elephants move across the landscape.

The K. Lisa Yang Center for Conservation Bioacoustics is a world leader in acoustic monitoring, from developing hardware, deploying and maintaining acoustic grids, designing software for analysis, visualization, storage of sound data, and analyzing “big data”. Katy Payne, founder of the Elephant Listening Project, was there from the start when Christopher Clark (who worked with Katy on the coast of Pategonia) began to build the center into the first-class program it is today.

Evolution of Passive Acoustic Monitoring (PAM)

Autonomous Recording Units (ARUs), designed to record unsupervised for extended periods of time in nature, have changed dramatically along with the revolution in computer technology. The Cornell Bioacoustics Research Program (BRP) was an early leader in the design and use of ARUs, both in the ocean and on land. Our first terrestrial recorders (pictured above) were built into PVC sewer pipe with a laptop computer hard drive for data storage and circuit boards that wrote the sound files in binary format. Each ARU in ELP’s first major project in Gabon needed a whopping 16kg (43 lbs) of batteries to run for three months!

Our current recorder, called the SWIFT and also designed by BRP, requires only 1kg of battery power to run for three months. And this makes a huge difference in the cost of a typical ELP project because we are operating in such remote forests. One of our biggest expenses is the cost of sending in a team to maintain the recording grid and to collect the data.

In this regard, it might be fun to describe a project that we did in 2013 where we were using acoustic monitoring to estimate the size of an elephant population in an area of northern Congo. The map below shows the study area, extending from the Lingoue River on the east, westward toward the main road running south from the city of Ouesso. Setting out the ARUs required three different missions, each one originated in the village of Liouesso, north of the map, and required one to three days travel down the Lingoue River in a pirogue (dugout canoe). Somewhere along the western bank of the river, the pilot would find a place that we could get out onto dryish land (sometimes extensive marshes bounded the river almost 1km wide). Then we would start walking westward through the forest, following elephant paths when we could, or chopping a way through when we couldn’t. On the longest mission (22 days long) the team was composed of Peter, his Chef du Mission, Brunell Ngombe, and five porters to carry food, camping equipment, and the ARUs.

A New Image of Forest Elephants

Thermal imaging (also called “thermography”) has given us a new window into the social behavior of forest elephants. Of course the potential of scientific insights motivated our research (see links in sidebar), but the incredible beauty of the images was a treat in itself!

The color scale in the image at right ranges from 27.1-37 degrees Centigrade (dark blue to white), graphically painting the temperature of this elephant’s skin at 10 pm in the evening.  Notice that even the warmest parts of his skin are several degrees cooler than the normal core body temperature of 37 C. This makes sense because the skin is used for thermoregulation and is usually cooler than the body core (touch your own skin and see that it tends to feel cool).

With information on ambient temperature and humidity, this thermal camera can be calibrated quite exactly and integrates the distance to the subject into the color scale. Many people wonder why there is a reflection in the pool. The explanation is that thermal energy is one part of the electro-magnetic spectrum that describes light. The surface of the pool is very cool and reflects this thermal “light”—but notice that the reflection is cooler than the actual elephant’s body! This is because the water absorbs some of the thermal energy and reflects back cooler radiation.

What is really “cool” is that we might be able to use some of this information to assess the health of an individual and in some cases we can see indicators of reproductive condition. For example, a pregnant female with no nursing calves will have noticeably hotter breasts than a female who is nulliparous (has never had a calf) because the tissues in her breasts are metabolically active preparing for lactation.

Where are you?

Acoustic arrays, which allow us to tell where a call originated, are very powerful tools. They are also rather intensive to use because an array typically needs five or more recording units, they must have clocks synchronized to the millisecond level of accuracy, and they need to be spaced close enough together that three or more record the same call.

Below is a short animation that shows how this works.

Acoustic arrays are critical for answering questions like:

• How many calls does a single elephant make in a given time period? (We need this to estimate the size of an elephant population from calls sampled across a huge landscape.)
• When calls can be so low that we can’t hear them from an observation tower, an array can tell us who gave a call that was associated with some interesting behavior. (We are doing this at the Dzanga Bai to probe the “elephant dictionary” or to find out who called at night.)
• We can follow the fine-scale movements of individual elephants as they approach a forest clearing (or as they leave it)

Ears on the forest

In 2007, after Katy Payne and Mya Thompson finished their pioneering work figuring out how to use acoustics to study forest elephants, the Elephant Listening Project got started on applying these methods to answer a diverse range of questions. We have studied the effects of oil exploration on elephant behavior, characterized seasonal use at a multitude of forest clearings, and probed the nocturnal behavior of forest elephants. We have now amassed nearly one million hours of sounds from the forests of Central Africa!

This invaluable archive of sounds establishes not only an historical record of the acoustic forest, but a source of research material for a multitude of acoustically active species. All of these sounds are available to other researchers for studying the presence of birds, insects, and amphibians; the intrusion of human sounds; changing biodiversity through seasons and through time.

Unlike some countries in the region, Gabon, Congo, and Cameroon have reasonably stable governments and large tracts of intact and pristine forests (percent of land area protected 22%, 41% and 11%, respectively). Overall, Central Africa has the second largest contiguous rainforest on earth, second only to the Amazon. This presents an exceptional opportunity for the conservation of tropical rainforest diversity, including charismatic animals like forest elephants, lowland gorillas, chimpanzees, mandrills, and myriads of other animals and plants that share this ecosystem. Gabon, with an unusually low human population density for this region of Africa, may well be the stronghold of the forest elephant and it is therefore imperative that we ensure protection here. The Elephant Listening Project worked extensively in this beautiful country between 2007 and 2014, developing new acoustic monitoring methods and establishing our first team of Gabonese acoustic researchers.

Some highlights:

• In Loango National Park, on the coast of Gabon, ELP has studied the effects of oil exploration on the ecology of forest elephants. We discovered, for the first time in this area, that illegal hunting was going on big-time within the national park. This spurred establishment of an anti-poaching patrol program that continues today.
• We established a series of studies at forest clearings, some within logging concessions and some in protected areas. We found that elephant activity was strongly seasonal in some but not in others. At all clearings elephants are more active at night than during the day, but they can become totally nocturnal when poaching pressure in the area is high. Documenting the relative intensity of use of different clearings is critical for successful management of the forest elephant, and our acoustic methodology is excellent for long term monitoring of remote locations without human presence. One clearing, located in a forestry concession, has more elephants at some times of year than any other location known in Central Africa, with the exception of Dzanga Bai in the Central African Republic.
• Along with colleagues from Oxford University and James Madison University we established the first grid of acoustic units to monitor illegal hunting within a national park. In Korup National Park, Cameroon, we could map in fine temporal detail how hunting pressure changed through the week in response to market day in the nearby villages. This sort of information can be used to help tailor anti-poaching patrols to the most effective times and locations. And, we can evaluate their effectiveness by quantifying actual change in recorded gunshots under different patrolling regimes.