Recording Elephant Conversations

  • 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

Related Links

Using Trees as Cleaning Tools

  • Argonne researchers and technicians are tracking how well poplar trees are containing and removing toxic solvents (such as Trichloroethane, 1,1-Dichloroethane, and 1,1,1-Trichloroethane, Trichloroethylene) from underground water. Pictured here are Cristina Negri, Lawrence Moss, John Quinn, Rob Piorkowski. (Photo by Shawn Allee)

When you think of cleaning up toxic waste, you might think of technicians digging huge holes
and carting off contaminated soil. It’s expensive, and they’re often just putting the soil and the
problem, somewhere else – say, to a hazardous waste landfill. Shawn Allee met researchers
who hope trees can clean some toxic waste, and leave the landscape in place:

Transcript

When you think of cleaning up toxic waste, you might think of technicians digging huge holes
and carting off contaminated soil. It’s expensive, and they’re often just putting the soil and the
problem, somewhere else – say, to a hazardous waste landfill. Shawn Allee met researchers
who hope trees can clean some toxic waste, and leave the landscape in place:

Argonne National Laboratory is a Big Science kinda place.

It’s a federal lab southwest of Chicago where they study particle physics, nuclear energy, and
advanced environmental clean-up.

The irony is, the place has been around so long, it’s now cleaning up its own environmental
messes.

In fact, it’s Larry Moss’s job. He takes me to a toxic waste site where trees help clean the soil.

More on those trees in a sec – first, here’s why Larry Moss needs them.

“This site was a very busy site back in the 50s and 60s. We had a large manufacturing process
for reactor components – did a lot of testing of reactor assemblies and different fuel mixtures. And to
do that you had to clean all that equipment and a lot of that solvent came down here.
There was a unit that was called a French drain, which basically was a trench filled with gravel. They would come down here and dump chemicals into this trench, and their theory was it would dissolve into the ground. They
thought it would just go away.”

Those solvents did not go away. They leeched into underground water.

The solvents potentially cause cancer and other problems, so the government said Argonne
needed to do something about the mess.

Researcher Christina Negri lays out what the options were.

“Put a parking lot on top of the pollution area
and basically leave it there forever. The other extreme, it would have been: dig out the soil, take it
somewhere – where you haven’t changed much. You’ve moved it from here to a landfill. That’s not the solution as
well.”

Those options – covering it up or carting it off – are also expensive.

So, Argonne researchers figured they’d try something new.

Negri says they hope to eliminate pollution on site – with the help of poplar trees.

Negri: “We’re taking advantage of a trait that these trees have to
go about finding water.”

Allee: “Let me get a closer look at a tree, here.”

Negri: “What you have to picture in your mind – See the height of the tree?”

Allee: “I’m looking at one that’s as tall as a three story walk-up building I live in.”

Negri: “You have to flip it 180 degrees and imagine the roots are going down that deep.”

Negri says they coaxed the roots into going straight down instead of spreading out. It seems to
work; the poplar trees are sucking water out of the ground and taking up solvent.

“Part of it is degraded within the plant. Part of it goes out into the air, which sounds like an
ominous thing to say, right? But if you do your calculations right, there’s much less risk when
these compounds are in the air than there is when they’re down 30 feet below.”

Negri’s team hopes the poplar trees will be more sustainable and cheaper than alternatives, but
they’re likely to be slower.

After all, it took years for the trees to grow. That’s fine for Argonne, because no one’s at risk – but that’s
not the case everywhere.

“Arguably, this is not the remedy you would adopt if you had, like, a tank spill or something that
you really need to go in right away, clean up and be done very quickly. It’s not a remedy if there’s
anybody’s at risk.”

This isn’t the only attempt to use plants to clean up toxic waste. The science behind it is called
‘phytoremediation.’

In other examples, scientists tried alpine pennycress to clean up zinc, and pigweed to suck up
radioactive cesium.

Negri says the trick is to use the right plant for the right toxin and know whether the plants stays
toxic, too.

Still, she says, toxic waste is such a big problem, it’s good to have lots of tools in your clean-up
toolbox.

For The Environment Report, I’m Shawn Allee.

Related Links

Climate Change and Wildfires

  • Jennifer Pierce and David Wilkins stand in front of a ponderosa pine forest just outside the city of Boise. They hope to study the relationship between fire and climate here and recreate a snapshot of ancient climate. They are both teach at Boise State University's Geosciences Department. (Photo by Sadie Babits)

Twenty years ago this year, the
country watched its oldest national park
go up in flames. Looking back, scientists
believe the 1988 fires of Yellowstone
National Park were the signal fire of
climate change. Researchers have been
working ever since to understand this
relationship between climate and wildfire.
Sadie Babits reports on two scientists
searching for clues to ancient climates,
using trees as their guide:

Transcript

Twenty years ago this year, the
country watched its oldest national park
go up in flames. Looking back, scientists
believe the 1988 fires of Yellowstone
National Park were the signal fire of
climate change. Researchers have been
working ever since to understand this
relationship between climate and wildfire.
Sadie Babits reports on two scientists
searching for clues to ancient climates,
using trees as their guide:

Jennifer Pierce wears work boots as she plows down a steep slope in a
ponderosa pine forest.

(sound of walking, twigs breaking)

Her blonde hair is tucked up under her Boise State bronco cap, but it keeps
sneaking out. She has to keep brushing it back under. She and her
colleague David Wilkins are professors who work for Boise State
University’s Geosciences Department. They’re in the middle of tall pines in
a forest just outside of Boise, Idaho. Suddenly she’s crashing across the
brambles and heads for this tree.

“Oh that’s a great one! Wow! Sweet!”

She drops to her knees and shows me how this tree has been scarred by
fire.

“You see this little V shaped cat face here at the bottom of the tree that’s
blackened? So during a fire when the bark of the tree gets damaged that
preserves a record of the fire as a scar on the tree.”

Pierce says since the tree has annual growth rings, she can tell when the
tree got burned.

It’s one way Pierce and Wilkins reconstruct the fire history of this forest.
It’s a key to understanding how climate has affected forest fires in the past.

“I think as we move into a likely warmer and drier future, it’s going to be
increasingly important to understand the relationship between climate and
fire.”

She says climate is the primary control for wildfires. As the West warms,
there’s less control. Recently, that’s meant a lot more wildfires.

(popping sound) “There you go!” (sound of a drill bit going through the tree
with sound of birds and forest)

David Wilkins is twisting an auger into the tree.

“It’s a good upper body workout!” (laughs)

It’s a way to take a sample of the rings of this tree. Within a half-minute,
Wilkins’ auger is stuck. The tree is rotten inside. An eight-inch core is all he
gets.

(sound of drill bit coming out of the tree)

Jennifer Pierce takes a look at this sample Wilkins twisted out. The rings –
some light, some dark – reveal just how the tree has responded to moisture
and temperature.

“If you have a tree that kind of is at the edge of its comfort zone so to
speak, it will be more of a sensitive recorder of those environmental
stresses. See this one looks pretty good.”

Tree rings aren’t the only clue these scientists use to reconstruct historic
climates.

(scraping sound)

“I didn’t bring my big shovel. I kind of feel naked without it.”

Pierce scrapes away dirt and she finds bits of charcoal. She can sometimes
use charcoal for radio carbon dating. But these won’t do.

“But, um, I wouldn’t use them for dating because you want to make sure
that the charcoal is stratographicly in place and that you haven’t had
critters burrowing and mixing things up.”

Charcoal can be dated much further back than the tree rings. It helps
Pierce and Wilkins understand what happened here thousands of years
ago. With samples from other scientists, they’ll get a snapshot of ancient
climate and how it affects wildfire.

And possibly determine what climate change will mean for forests in the
future.

For The Environment Report, I’m Sadie Babits.

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