Tools That Leave Wildlife Unbothered Widen Research Horizons
The New York Times 9 Mar 09;
You may remember Senator John McCain’s criticism of a study of grizzly bear DNA as wasteful spending. And you may have wondered how the scientists got the DNA from the grizzlies.
The answer is hair. The study, which Mr. 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. And 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 C. Kendall, a research ecologist with the United States 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. And 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 types of scat on the ground that cannot be differentiated visually. Out of 100 fecal samples gathered, often only 2 belong to a snow leopard. Lab testing to find those two samples is expensive.
The scat is shipped to Bozeman, where Dr. Parker is training a dog, a Belgian Malinois named Pepin, to tell snow leopard scat from other types. 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 K. Schwartz, a research ecologist at the United States 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,” Dr. 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 R. 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 tracks,” Dr. Foresman said. The setup costs $12.
For a study on river otters, Dr. Foresman used Google Earth to find log jams on the Bitterroot River. “Otters love log jams,” he said. The next day he went to a jam and set up a remote camera. “I had a hundred pictures of river otters in one night,” he said.
Such techniques are easier on researchers as well as their subjects. Tracking animals with a radio collar often means flying low in treacherous mountain weather.
“People get hurt all of the time,” Dr. Foresman said. “I know a lot of wildlife researchers who have died in plane crashes while tracking animals.”
The trend has unleashed a burst of creativity. In Portugal, biologists studying the Eurasian lynx outfit a lynx den with cork in which an Amazonian kissing bug is contained in a hole the width of a quarter, covered by thin plastic. The kissing bug drills through the plastic, bites the animal and goes back into its hole. When the lynx leaves, researchers fetch the bug and take the blood sample.
In Yellowstone National Park, fish in Yellowstone Lake carry naturally occurring mercury from underwater thermal vents up through the food chain. After feeding bears in captivity with trout harvested from the lake, researchers know precisely the ratio of fish eaten to mercury in hair and blood. So they have an accurate continuing window into how much fish the bears are eating simply by gathering hairs.
Museum specimens of wildlife, relegated to dusty and forgotten corners, are also playing a new role in modern research, because of the usefulness of a bit of DNA from a skull or a hair. A sample from a fisher, mounted in 1896 and found in a museum at Harvard, helped biologists determine that there is a population of genetically distinct fisher still living in Montana.
Although noninvasive approaches have opened windows into the lives of wildlife, there are drawbacks. “I got into the field to watch wild behavior and to hold an animal,” said Chuck Schwartz, head of the Interagency Grizzly Bear Study Team in Bozeman. “That’s special. But with noninvasive that doesn’t happen.”
In addition, the data quality from feces is often poor. “To avoid error you have to repeat the study sometimes multiple times,” said Gordon Luikart, a wildlife geneticist at the University of Montana.
So the traditional method of “capture, mark, recapture” is still a vital tool that is complemented by the noninvasive techniques.
“We still mark animals,” Dr. Schwartz said. “It’s remarkably informative.”