By Jim Robbins New York Times
Posted: 03/10/2009 10:19:39 PM PDT
You may remember Sen. John McCain’s criticism of a study of grizzly bear DNA as wasteful spending. You may have wondered how the scientists got the DNA from the grizzlies. The answer is hair. The study, which McCain referred to during his run for president, was a large one, and it provided an estimate of the population of threatened grizzly bears in the Northern Continental Divide Ecosystem, in and around Glacier National Park. The researchers did not trap the bears or shoot them with tranquilizers. Instead, they prepared 100 55-gallon drums with a mixture of whole fish and cattle blood that was allowed to ferment until it had the aroma of grizzly bear candy. They built 2,400 hair corrals — 100 feet of barbed wire around five or six trees — and placed the fish and blood mix in the center. When bears went under the wire to check it out, they left hair behind. The team collected 34,000 hair samples in 14 weeks this way. The population estimate from the study, announced late last year, was 765, a figure 2.5 times the estimate based on sightings of females and cubs, the previously used method. “Hair snaring has given us a much more precise number,” said Katherine Kendall, a research ecologist with the U.S. Geological Survey who designed and implemented the study. The results were just published in The Journal of Wildlife Management. It also gives a glimpse of a growing trend in wildlife biology toward research methods that are gentler — and cheaper — than the classic “capture, mark, recapture.” In that process researchers trap an animal, sometimes drug it and fasten on a radio collar or implant or attach a transmitter. Then, they follow the radio signal or catch the animal again to see where it goes. Such tools are powerful. Some high-tech collars beam an animal’s whereabouts to a satellite every 20 or 30 minutes, giving researchers unparalleled data on movement and habitat. But the techniques can create animals that are either “trap happy” or “trap shy.” There is concern that contacts with humans can reduce an animal’s wildness or lead to its death. Some research shows that bears may suffer long-term impacts from being drugged. In national parks, visitors often complain when they see a wild wolf or bear with a large radio collar around its neck. As a result, new noninvasive techniques are evolving, some that use hair and others that use animal scat. Such methods can be useful in countries that lack access to expensive technology. “You don’t need a vet, you don’t need an airplane, you don’t need training,” said Megan Parker, assistant director of the Wildlife Conservation Society’s North America Program, based in Bozeman, Mont. In Bhutan, for example, biologists are gathering scat to study snow leopards, which are extraordinarily difficult to see, let alone trap. The problem is that there are a lot of different kinds of scat on the ground that cannot be differentiated visually. Out of 100 fecal samples gathered, often only two belong to a snow leopard. Lab testing to find those two samples is expensive. The scat is shipped to Bozeman, where Parker is training a dog, a Belgian Malinois named Pepin, to tell snow leopard scat from other kinds. Once Pepin’s sniff test weeds out the false samples, the right scat can be sent to a lab. Because of technological advances, a fragment of DNA found in scat can identify the species and sex of the animal that produced it. By collecting numerous samples across a territory, critical migration corridors can be identified as well as the abundance of a species. Stress hormones in the sample may be an indicator of the animal’s health. Diet and parasites can be assessed. “The genetic code is a mystery novel, a history book and a time log in a single hair,” said Michael Schwartz, a research ecologist at the U.S. Forest Service’s Rocky Mountain Research Station in Missoula, Mont. L. Scott Mills, a professor of wildlife population ecology who teaches the techniques at the University of Montana in Missoula, said noninvasive methods “opened the door for abundance and density estimates that are very hard to do with live trapping.” “We can sample so many more animals,” Mills said. “With live trapping you might trap three animals in two years. With scats we can find 15 or 30.” Another noninvasive technique involves the use of still and video cameras triggered by heat and motion. Kerry Foresman teaches in the wildlife biology program at the University of Montana in Missoula, which emphasizes noninvasive techniques. He studies the fisher, wolverine, lynx and pine marten, all secretive carnivores, leaving a remote camera trained on the hanging hindquarter of a deer. Tracking plates are another tool. Animals are lured by bait across soot-covered metal plates and onto contact paper. “They leave behind exquisite images of their track s,” Foresman said. The setup costs $12.