Biology Reference
In-Depth Information
“Let's go find some jaguars!” George shouted to me over the engine noise. He gave a
thumbs-up to the pilot, who then set the Cessna hurtling down the grassy, water-soaked run-
way in hopes of clearing the tall forest wall that surrounded us on all sides. It was a joy and
a relief to rise above the living curtain of trees into a beautiful sunrise. Below were trees in a
thousand shades of green as far as the eye could see, dotted by occasional ones with young,
bright red leaves and a few with crowns awash in yellow or pink flowers.
What appeared to be a single type of forest, however, was many forests in one. Meandering
rivers are a trademark feature of the Amazon basin and shape the extent of floodplain forest,
where tree species must cope with periodic inundation. The high disturbance levels contrib-
ute to floodplain forests being less rich in species than the more stable upland forests, bey-
ond the reach of seasonal floods. These upland stands are among the most diverse forests in
the world. A thousand shades of green may not be far off as an estimate: perhaps as many
as 1,000 woody tree and vine species populate the area, though the tree species occur at ex-
tremely low densities.
In a clearing along the banks of the Madre de Dios, the buildings of the Los Amigos Biolo-
gical Station gleamed in the morning sun. As the plane circled, George found his first radio-
collared jaguar. Locating jaguars by plane may seem romantic, but it was really a throw-
back to the old ways of wildlife tracking. The schedule of determining one location a month
for each collared cat would yield few answers to George's overarching questions. Frustrated
but determined, he considered satellite telemetry using global positioning system collars. But
even with expensive GPS collars, he concluded, reception would be possible only when the
collared animals ventured into an opening, such as a rare natural clearing or a river sandbar.
The jaguars we were locating now reflected George's most recent solution to the problem
of tracking in such dense vegetation. As the plane swung toward the Tambopata River, the
signals of two more jaguars pinged in the headphones. Since 2006, some of the jaguars be-
low us had been carrying two complementary signaling devices, one traditional—which was
giving George the location he heard in his headphones—and the other a piece of wizardry.
Mounted on the standard VHF radio collar was a TrackTag, a device invented by the Scottish
engineer Peter Brown that obtains a fix in about twenty milliseconds—a significant improve-
ment over normal GPS collars, which take at least ten times that long. Using this technology,
George collected thousands of fixes, rather than the few he could obtain using VHF collars,
over the course of our three-hour flight on that first of our two-day jaguar reconnaissance.
“It's really pretty ingenious,” George said later. “After the TrackTag picks up the signals
of the GPS satellites, it stores hundreds, perhaps thousands, of fixes on a chip rather than at-
tempting to transmit the location back to us via a communication satellite, as other GPS tags
do. After we recapture the animal, we swap the TrackTag and download its data. But if we
don't recapture it, we can program the collar, with VHF and TrackTag, to drop off the anim-
al. Then I can fly, locate the dropped collar using the VHF device, and send my field crew
