Elephants talk amongst themselves below levels we can hear. (Photo courtesy of the Elephant Listening Project in Dzanga National Park)
Biologists are always trying to
get a good count of the animals
they’re studying. You wouldn’t
think it’d be that hard to find
an elephant for a count, but even
some of the largest animals are
difficult to count in the wild.
So researchers are now trying new
methods. Emma Jacobs reports on
a Cornell University project which
is using audio recordings to learn
more about elephants:
Transcript
Biologists are always trying to
get a good count of the animals
they’re studying. You wouldn’t
think it’d be that hard to find
an elephant for a count, but even
some of the largest animals are
difficult to count in the wild.
So researchers are now trying new
methods. Emma Jacobs reports on
a Cornell University project which
is using audio recordings to learn
more about elephants:
Mya Thompsons sits down in her lab and pulls up a set of recordings on her computer. She helped tape these sounds for the Elephant Listening Project in Dzanga National Park in the Central African Republic. She plays a recording made in the forest, late at night.
(sounds of the forest at night)
“You heard some insects, you heard some sort of the din of a nighttime forest.”
But you probably don’t hear elephants.
Next, Thompson takes the same sound and speeds it up on her computer. Suddenly, you can hear something else.
“This is 4-times normal speed.”
(sound of forest at night, but with rumbles)
Elephants make those low rumbles. When she speeds up the playback, they rise in pitch. It’s kinda of like the voices of Alvin and the Chipmunks.
It turns out elephants talk among themselves below levels we can hear. Biologist Kaity Paine discovered these sounds in the 1980s. She realized that because elephant rumbles are so low, they travel long distances. This should make them useful to track elephants over wide forests, but Thompson remembers that in the field, it was hard to see how.
“We’re collecting all this information and we wanted to know what the calls were like, but because we can’t hear them, we were almost totally in the dark about what was going on.”
When she got back to New York, Thompson and the rest of the research team started combing through all the audio and video collected in Central Africa for elephant calls. It took thousands of hours.
But with time, they could nail down a pattern. The key was a relationship between the audio recordings and the video of elephants they had made in one clearing popular with elephants.
“This is a communication system. There are a lot of other variables other than, ‘Hi I’m here,’ but, overall, the more calling, the more elephants and that was good news for us.”
Now Thompson can monitor elephants over huge areas of this dense forest using these audio recordings.
In the field, the team hoists their recorders into trees attached to truck batteries. They can stay up there a long time, which has real advantages.
“Usually, when you take a survey, you go, you count, and you leave. For acoustics, we’re able to have this recorder up continuously without all this human effort and make repeated estimates over longer periods of time.”
With enough information, Thompson can estimate at the numbers of elephants in a forest with twice the precision she could have before.
Marcella Kelly teaches wildlife field techniques at Virginia Tech. She says, when you can track animal numbers closely, you can see how they respond to changes in their environment. This is a must for conservation.
“We really need effective ways to estimate population size, especially because decisions are made on management based on what those numbers tell us, over time.”
The Elephant Listening Project recently started monitoring elephants in the African nation of Gabon.
“The authorities had allowed gas exploration to see if there’s any petroleum reserves there, and so our project was asked to monitor the forest for elephant calls before, during, and after this exploration.”
Thompson can already say that things have changed. Elephants have started coming out more at night than during the day to avoid people. In the end, hopefully she’ll be able to see just how disruptive changes have been and to pinpoint the human activities causing problems.
She also wants to protect other animals making noise in the forest, and outside it.
“We’re really hoping that these methods that we’ve developed, will be developed for not only forest elephants but for other species that are hard to survey that we really need to know more about before we can protect them.”
For right now though, Thompson is still in her lab, listening for elephants.
For The Environment Report, I’m Emma Jacob
