09 December 2006
Exclusive from New Scientist Print Edition
By the time Steve Gulick arrived, it was too late. The poachers had struck, and elephant carcasses carpeted the floor. "You could step from body to body without your feet touching the ground," he says. "Whole elephant families lay next to each other, gunned down for their tusks."
The massacre had taken place in the Mouadje Bai rainforest in the Democratic Republic of the Congo (DRC), at a spot well known among local poachers for the rich haul of ivory it can yield. Since 1994 Gulick has been helping the US-based Wildlife Conservation Society (WSC) to patrol the area in an effort to thwart these illegal hunters. It has been an unequal contest. Poachers target elephants under the cover of dense rainforest to avoid being detected from aircraft, and patrols like Gulick's have to trek through the forest on foot. Killings can go undetected for months or even years, and during one sweep, Gulick's patrol found more than 200 elephant carcasses in various stages of decomposition.
Now he and others are fighting back, using adapted military technology to listen in on elephants and monitor their behaviour. They are also borrowing data from environment monitoring satellites to spot illegal logging that can devastate the animals' habitats. Elsewhere, similar techniques are being applied to warn when other endangered species and habitats are being illegally plundered. "There's a real need to transform wildlife observation techniques into real-time warning systems," Gulick says.
To help achieve that Gulick has set up Wildland Security, a company based in New York City that specialises in sensors to detect wildlife crime. One of its products, a small seismic detector called TrailGuard, can be buried along forest pathways to pick up the footfalls of people as they pass. "It's based on military technology used to detect enemy troop movements," he says. To distinguish hunters from harmless passers-by, the devices also contain magnetometers that can detect iron in guns several metres away. Once triggered, the TrailGuards transmit a radio signal to an antenna at the top of the forest canopy, which relays it to a hub to be sent to forest rangers over a satellite phone link. "You can tell the number of people in the party and the direction they are walking, so you can come prepared, before the killing starts," Gulick claims.
The devices are about to be installed in a national park in the DRC as part of a pilot study being funded by the WSC. Ten TrailGuards will be laid out along the park boundary on major access trails used by poachers. "They are going to allow us to remotely monitor some of our most threatened areas," says Steve Blake of the WSC's centre in Libreville, capital of nearby Gabon. TrailGuards are also being deployed in the Osa Peninsula on the Pacific coast of Costa Rica, where poaching is threatening to wipe out the region's jaguars and peccaries, and in the hard-to-reach Altai Republic in southern Russia, where poachers arrive by helicopter each winter to illegally hunt snow leopards for their coats.
For the elephants, an additional line of defence could come from acoustic sensors being developed by Mya Thompson and colleagues at Cornell University in Ithaca, New York. These so-called "autonomous recording units" were originally designed to monitor elephants communicating with each other in Kakum National Park, Ghana. As well as the familiar screams and trumpeting, elephants emit rumbles at between 5 and 30 hertz, which is partly below the range audible to humans. These low-frequency sounds travel farther than audible frequencies and can be heard by other elephants at least 4 kilometres away. They are particularly useful for tracking the animals, says Thompson, whose team has used the elephant calls to create real-time maps showing which sites elephants visit and when. "We can identify their hotspots, feeding areas and watering holes," she says.
The devices pick up the elephant calls using specialised low-frequency microphones hidden in trees, and record the signal onto a laptop computer. Installing the microphones 100 to 200 metres apart ensures that each call is picked up at a minimum of three points. The millisecond differences in the time it takes to reach each sensor can then be used to locate the origin of the sound. The devices can store three months' worth of continuous data and use very little power, so once installed they can simply be left in place, relaying data back to the lab. "We don't have to go in and disturb the elephants' habitat, so they feel safe, giving us the best conditions to eavesdrop on them," Thompson says.
Unfortunately, it isn't only the elephants that feel safe. The poachers do too, and they have continued to hunt the animals. So the team asked a group of engineers led by Christopher Clark, also at Cornell, to tune their eavesdropping software to pick out the sound of gunfire from the data stream. The engineers are developing software that will automatically notify rangers as soon as shots are heard. Thompson's group plans to test the gunshot detectors in the DRC alongside Gulick's TrailGuards. "It's a really important last resort option, although sadly once a gunshot has been heard, at least one elephant has been hurt," Gulick says.
Monitoring the elephants' movements can also alert rangers to another threat to the animals: illegal logging. Tropical hardwood is a major export from central Africa, and some companies in the DRC are moving beyond the areas in which logging is allowed and opening up previously untouched forest. This is bad news for the elephants, Thompson says. "Their habitats are destroyed and fragmented and they are forced to run through open areas to reach food, exposing them to poachers."
Help in spotting the spread of illegal logging could also come from a technique designed to monitor signs of climate change. NASA's Ice, Cloud, and Land Elevation Satellite (ICESat) measures small changes in the thickness of the Greenland and Antarctic ice sheets using LIDAR, a laser technique that maps features in a similar way to radar but using light rather than microwaves. The LIDAR scanner creates similar 3D images of the interior of any forests it passes over, revealing damage to smaller trees that may be hidden from the naked eye. A team led by geographer Peter Hyde at the company Science Systems and Applications in Greenbelt, Maryland, which works with NASA's Goddard Space Flight Center, also in Greenbelt, has already found clear evidence of illegal logging by analysing data from ICESat gathered over six months.
Having demonstrated the effectiveness of the technique, Hyde hopes to secure funding to fly LIDAR scanners aboard aircraft over the forests of central Africa. Thompson thinks this would be a big step forward. "Right now in central Africa, we have parks that are supposedly protected from illegal logging, but that's only on paper, because in practice it's just too difficult to monitor," she says. "Perhaps this will help us stop logging in these so-called protected parks now." From issue 2581 of New Scientist magazine, 09 December 2006, page 30-31