Science / Medicine : Listening in, Out of Sight : Satellite technology has recently become economical, adding a high-tech wrinkle to wildlife tracking. Scientists can tag along with the animals from the lab.
Keeping secrets from Bruce Mate isn’t easy. Not long ago, for example, while sitting in his office at Oregon State University, the far-seeing marine biologist kept watch on a humpback whale thousands of miles away in the North Atlantic.
Mate was tracking the whale via two space satellites, which relayed signals from a small transmitter fixed to the animal’s back.
Scanning the screen of his office computer, Mate knew the latitude and longitude of the whale’s location. Other numbers told him how deep the whale was diving and how long it remained submerged. From this and other information, the scientist could even deduce what species of fish the humpback was likely feeding upon.
Since becoming economical in recent years, satellite technology has added a high-tech wrinkle to the ancient art of wildlife tracking. Eyes in the sky have freed researchers like Mate from the limitations of conventional radio telemetry, allowing them to tag along with deep-diving whales or track blizzard-bound musk oxen.
In the process, they’ve gathered new intelligence on a host of species, sometimes collecting facts that might be used in protecting the animals.
Take caribou, for instance, which are faced with disturbance from energy development. “For the first time ever, we are able to get a clear picture of the Arctic migration of the Porcupine caribou herd,” said Larry Pank, a U.S. Fish and Wildlife Service biologist in Fairbanks, Alaska. “We’ve found it totals twice the distance we previously estimated,” or up to 1,800 miles.
Sea turtles, polar bears and manatees are all being tracked from the polar-orbiting Tiros weather satellites of the U.S. National Oceanographic and Atmospheric Administration.
“The satellites carry a bunch of different experiment packages,” said Stan Tomkiewicz, director of wildlife programs for Telonics Inc., a Mesa, Ariz., firm that has been instrumental in developing wildlife tracking technology. Information in the form of electronic pulses is transmitted from the animal to the satellite, then dumped to ground stations. There it is translated and fed into an international computer linkup for scientists.
Of various kinds of data the system can provide to scientists, an animal’s whereabouts may be the most essential. “Location is very important to us,” Mate said. “With many kinds of whales, we don’t know where they are for half the year. Because we don’t know that, there’s no way we can give that extra measure of protection to feeding grounds, migration routes or calving areas.”
Mate may have been the first scientist to demonstrate the promise of satellite tracking of whales. That was in a 1983 project investigating the potential effect on endangered whale species of oil and gas development off Newfoundland.
“We started with a six-day experiment on a humpback,” Mate said. “The satellites gave us 10 whale locations during 121 messages about dives and indicated the water temperature. We tracked the whale 450 miles along the shear zone between the Gulf Stream and the Labrador Current.
“Whales seem to use these oceanic structures to locate and catch fish. The tagged whale swam directly from one feeding area to the next in a perfect straight line--showing an impressive display of navigation.”
Whale scientists know that humpbacks often use ocean currents and differences in water temperature (known as thermoclines), to help them navigate and to capture prey.
“We’ve found that humpbacks actually round up their quarry much the same way that cowboys round up cattle,” Mate said. “Some, for example, drive capelin (a herring-like fish) down to a thermocline that acts essentially like a box canyon. The capelin don’t like the colder water and stop, only to be scooped up by the waiting humpbacks.”
The Tiros satellites also provide Mate with ocean-surface temperature readings. With these he can determine when a humpback has entered a thermal front area. Knowing that, plus the water temperatures generally preferred by capelin, and the temperature of the water a whale has dived to, Mate can “deduce that the animal is there feeding on capelin and using thermoclines to crowd the fish.”
That sort of high-tech wizardry has only whetted Mate’s appetite.
“It’s very exciting because there are so many questions we can realistically seek answers to now. For example, we can identify migration routes and critical habitat areas so we can protect them. We are attempting to determine how much of each day gray whales need for feeding during stationary periods in order to endure the five-month fast that occurs during migration. And we hope to learn how the humpbacks locate their fishing grounds. Is it by memory, or by ocean parameters that indicate capelin habitat, or do they hear other whales?”
If satellite tracking is so useful, why have scientists not relied on it until now?
“It has been too darned expensive and the transmitters have been too heavy until recently,” biologist Pank said. “But a couple of years ago, the scientists at Telonics came up with a way to drastically cut the cost and weight of the transmitters.”
At close to $3,000 each, the transmitters (which weigh 2.5 pounds and measure the thickness of two packs of cigarettes) are still expensive. But they used to cost $12,000.
Moreover, while traditional radio tracking is still more effective and less costly for some kinds of wildlife research, satellite telemetry can be a bargain. Tracking whales from a boat, for example, can cost more than $2,000 a day. Agencies receiving satellite information pay a $3 daily fee.
Satellite telemetry can also save lives. “Three or four scientists lose their lives every year attempting to track animals by airplane during bad weather,” Tomkiewicz said. “But by putting satellite transmitters directly on animals, scientists can remain safely inside while the transmitters send back information during even the most severe Arctic storm.”
That transmitter reliability can puzzle as well as enlighten scientists.
Consider, for example, the loggerhead sea turtle that visited Kansas. Released near Gulfport, Miss., the 212-pound turtle was tracked for nine months, during which it journeyed, like any reasonable sea turtle, 1,500 miles along the Texas coast. But a final fix on the turtle, showing it to be in Salina, Kan., had scientists scratching their heads.
“At first we thought it was a glitch in the system,” biologist Larry Kolz said. “But then we tracked the transmitter to a farmer’s backyard in Salina. He said he found it on the beach in Texas while he was fishing and brought it home for his kids to play with.”
Satellite tracking has also surprised scientists by showing them that some animals can move more rapidly than they had thought. A manatee fitted with a transmitter by Florida scientists swam an astonishing 30 miles in a single night. A female polar bear, also linked to scientists via satellite, logged 300 miles in three days.
Such findings have led to an explosion in satellite-tracking projects.
In Australia, plans are under way to tag feral camels, kangaroos and saltwater crocodiles with transmitters. In Africa, there is hope that elephants and gorillas that migrate into countries closed to research biologists can still be followed with satellites.
In Alaska, Pank and other scientists are using information gathered by satellite to develop a complex model of animal energetics. Their goal is to learn how a caribou’s daily energy needs vary with changing weather, the availability of habitat and disturbances from oil and gas development. Nearly two dozen caribou were fitted with transmitters last year in an effort to collect satellite data. Pank, however, does not foresee the day when biologists will receive all of their information about wildlife from orbiting satellites.
“Nothing will ever replace the need for scientists to actually observe wildlife in its natural habitat,” Pank said. “Satellite tracking is just another tool in the wildlife biologist’s kit.” But, he added, “it’s the best tool that’s come down the pike in a long, long time.”
