Tracking Forest Creatures on the Move
Tuesday, February 03 2009 @ 07:37 PM UTC
Contributed by: Don Winner
“Nothing seems to slow them down,” Dr. Crofoot said. “They never stop moving.” Neither did Dr. Crofoot, 29, who is tall, blond and sporty and who reminded me of the actress Laura Dern in “Jurassic Park.”
It was January and supposedly the dry season, but suddenly the skies burst into rain. So now would the monkeys hunker down and wait out the storm? “I wish,” Dr. Crofoot said. How about mutual grooming? Surely they have to stop for that. “Capuchins groom each other occasionally,” she said, “but much less often than, say, baboons or chimpanzees.”
Yet somehow the capuchins manage to either outwit or outrun the forest’s legions of parasites. Of the dozens of monkeys that Dr. Crofoot has handled over the years, she has found ticks on only one or two. I, by contrast, spent a mere three days in the field and am still so covered with swollen red tick and chigger bites that I look like the color plates from a dermatology textbook.
Capuchins are smart, gorgeous and socially sophisticated, and Dr. Crofoot has relished the many hours spent studying them with the traditional field research tools of binoculars, notebook and a saint’s portion of patience. Yet she and other scientists who work here at the Smithsonian Tropical Research Institute are thrilled with a new system for tracking their subjects that could help revolutionize the labor-intensive business of field biology.
Called the Automated Radio Telemetry System, the method relies on seven 130-foot-high radio towers scattered across the island that can monitor data from many radio-tagged individuals simultaneously, round the clock, through the calendar. Once an animal has been outfitted with a transmitting device, the towers can track its unique radio signature and, by a process of triangulation, indicate where it is on the island, whether it’s moving or at rest, what other radio-endowed individuals it encounters.
The constant data streams feed into computers at a central lab building on the island, allowing researchers to stay abreast of far more animal sagas than they could possibly follow through direct observation, and to make the best of their hours in the field. If you see an extended flat line on your computer monitor, it’s time to go out, retrieve the corpse and figure out what happened.
And because transmitters can now be made as light as two-tenths of a gram, scientists can tag and track katydids, orchid bees, monarch butterflies, even plant seeds.
“Automated systems like this are ushering in a new era of animal tracking,” said Roland Kays, another institute research associate. “There’s a lot of potential for seeing the routes animals take and the decisions they make every step of the way.”
The application of radio telemetry towers, global positioning satellites and other cyberscapes to the mapping and deciphering of the natural world has spawned a new subdiscipline. “Movement ecology is the term being thrown around now,” said Dr. Kays, who is also curator of mammals at the New York State Museum in Albany.
Dr. Kays is applying the tracking system to explore the dynamic ménage ŕ trois among the island’s population of ocelots; the ruddy, snouty rodents called agoutis; and the island’s towering and thickly buttressed Dipteryx trees. The agoutis love Dipteryx seeds, and the ones they don’t eat immediately they bury for later consumption. The Dipteryx needs the agoutis to bury its seeds before ground beetles or other animals destroy them, but then the tree wants the rodent to conveniently disappear. Ocelots love agoutis; the rodents are their most important food source. The question Dr. Kays is asking: How many members of each sector are needed to sustain this tripartite economy?
The telemetry system adds to the scientific luster of an island that has been a research mecca ever since Barro Colorado’s 3,865 acres were separated from the mainland by the construction of the Panama Canal in 1914. “It’s a living laboratory,” said Stefan Schnitzer of the University of Wisconsin. “It’s the most heavily studied piece of forest in the world.”
Of course, what sounds dandy in theory can act buggy in practice, and researchers admitted that the upkeep of a complex computerized network in the pitilessly catabolic conditions of a tropical rain forest is always tricky. Moreover, tagging animals remains difficult, particularly when the subjects are smart and easily spooked, as capuchins are.
At the moment, only five of the island’s estimated 250 to 300 capuchins are fitted with radio collars, a figure that Dr. Crofoot hopes to double or treble. Once she is able to eavesdrop simultaneously on a representative sampling of the 15 to 20 capuchin social groups that roam the island, she can better address her abiding interest in intertribal politics.
“There have been decades of work looking at social relations within primate groups,” she said. “But primates have neighbors, and they’re with those neighbors over decades, so the question is, what are those relationships like?”
Early evidence suggests that capuchins are xenophobic but not imperialistic. “The tracking data indicate there’s lots of long-distance avoidance,” Dr. Crofoot said. The monkeys give especially wide berth to their versions of demilitarized zones, where one group’s territory overlaps with another’s.
The best way to win a war is not to start one in the first place: pure genius.