Scat-Sniffing Dogs
by Robin Meadows

Biologists can learn amazing things from poop—or scat (to be more scientific). The first step is using dogs trained to sniff out scat from a particular species, the second is analyzing the DNA in the scat. This powerful combination of low-tech and high-tech can give biologists a more accurate picture of wildlife populations than ever before, from how many animals there are to where they go. The technique can even identify individuals in a population. Scat sniffing is ideal for studying species like bears and tigers, which are hard to find and cover a lot of ground.

“You can get a lot of information on species without ever seeing a single animal,” says biologist Sam Wasser, who conceived the idea. Wasser worked at the National Zoo from 1989 to 1993, and was the first recipient of the NZP Research Scientist Development Award. He now directs the University of Washington’s Center for Conservation Biology in Seattle.

Another benefit of scat sniffing is that it’s non-invasive. The traditional method of studying carnivore populations is radiotracking, which involves trapping or tranquilizing the animals and then fitting them with radio collars. In addition to being stressful, this can sometimes cause injury or death.

Scat sniffing is catching on. Wasser is using it to study black and grizzly bears in the Pacific Northwest, and scat-sniffing dogs are also used to study tigers, cougars, lynx, wolves, foxes, and ferrets. The technique is not limited to carnivores or even to land animals; Wasser envisions that the dogs could also be used to study owls and right whales.

Ah-ha!
Wasser was primed to make the connection between scat and DNA for two reasons. First, he had already been analyzing hormones in scat. His laboratory pioneered the technique for measuring reproductive and stress hormones in scat, which can show whether animals are pregnant, what their stress levels are, and whether stress levels increase when their habitat is disturbed. Wasser brought this method to the NZP’s reproductive physiology program and, working with Steve Monfort and Janine Brown, used it on a wide variety of species, including owls, tree kangaroos, Alaskan moose, numerous cat species, wild dogs, maned wolves, and baboons.

The second reason that Wasser was primed to connect scat and DNA is that he had already been using a non-invasive method to collect bear samples for DNA analysis. This work, which was with the Washington Department of Fish and Wildlife, involved collecting samples of fur and analyzing the DNA in its follicles. The researchers collected the samples by putting a lure such as aged cow blood under barbed wire, which snagged the bears’ fur on their way to the bait. However, this method has a potential problem: it could bias the results because some bears were far more likely to come to the bait than others. For instance, most of the fur samples were from males because females, especially those with cubs, avoid the lures.

Wasser got the idea of analyzing the DNA in scat while talking to a colon-cancer researcher who used human feces for genetic studies. During digestion, gut cells slough off and are excreted in feces contains several million gut cells. The DNA in these gut cells is selectively multiplied using a molecular technique called PCR (polymerase chain reaction), which can make millions of copies of specific DNA segments. These segments can then be analyzed to determine the species, sex, and identity of the animal.

Scent connection
The next challenge was figuring out the best way to collect the scat. Wasser thought that having people look for it could be biased because scats from some animals are hard to find. For instance, many animals avoid trails and females with cubs may try to hide their scat. Inspiration struck at a 1997 bear meeting in Ocean Shore, Washington, where people were talking about the recent ban on hunting bears with hounds. “They were wondering what to do with the hunting dogs. I thought they could train them to scent scat but they said narcotics dogs would be better,” says Wasser.

It turned out that they were right. After a three-month search, Wasser ended up working with narcotics dog trainer Barbara Davenport, who manages the Washington Department of Corrections’ Canine Program. “Sam came up with the idea, and he and one of his researchers started calling police agencies. They all laughed and said ‘call Barbara Davenport,’” she recalls.

Davenport was perfect because she has been a dog person since she was ten, when she began working for a professional handler on the dog-show circuit. She had also trained and showed dogs through 4-H, and trained and groomed dogs at a kennel. Then her love of dogs led her to join the Army military police, where she learned how to train the dogs for patrol and narcotics detection.

At first, Davenport and Wasser trained scat-sniffing dogs under a cooperative agreement between the state Department of Corrections and the University of Washington. Now she collaborates with Wasser on her own time as part of her business, Pack Leader Dog Training, which trains stock dogs for competition. Davenport handles stock dogs herself and her Rottweiler has won a triple herding championship in cattle, sheep, and duck competitions.

Davenport based the scat-dog training on methods for training dogs to find illegal drugs. Dogs have such a keen sense of smell that they can even detect residue on drug paraphernalia. Narcotics training is rigorous; to be accredited, a dog and handler have to find 90 percent of the known samples hidden in a defined area.

The best dogs for scat sniffing are working breeds that are both large and agile enough to search four to five miles of demanding terrain per day. Scat dogs also must have the right personality. They have to be hard-working and, since handlers reward them with a tennis ball, they have to be driven to retrieve. “They’re unbelievably object-oriented, the only thing they want is their tennis ball all day long,” says Wasser. This characteristic makes them unsuitable for pets. “Most of our dogs are rescued from the pound. They’re unadoptable by the general public because they’re high-energy and destructive,” says Davenport.

Most of the 12 scat dogs she’s trained were also unsuitable for narcotics work, which means working on tight leash and following a comprehensive search pattern at the direction of the handler. “It’s very detail oriented and some dogs don’t want to do it,” says Davenport. “Scat work is much freer, there’s more odor and more running back and forth.”

Olfaction 101
Training a scat dog takes several weeks of intensive work. First, Davenport conditions the dog to associate the ball reward with the scat from a particular species. This entails putting the scat in one of five compartments in a scent box. Each compartment has a two-inch hole in the top so the dog can smell what’s inside. Then Davenport leads the dog down the scent box, tapping each hole so the dog will smell it. When the dog reaches the compartment that contains the scat, she immediately rewards the dog with the ball. Then she trains the dog to sit by the compartment that contains the scat. “This way they won’t touch, scatter, or add their own DNA to the scat,” says Davenport.

The next step is drilling the dogs in the field. “A scat dog is a cross between a narcotics dog and a wilderness search-and-rescue dog,” says Davenport. Working with Wasser’s team, she optimized the dogs’ field training on black-bear scat samples placed on McNeil Island, in Puget Sound. The island was ideal because it’s mostly forest, which is where the dogs would ultimately be searching for bear scat, and there are no bears, which meant that all the bears’ scat samples were known. The dogs did have to distinguish bear scat from other species, however, because McNeil Island has many coyotes and deer.

The dogs also have to recognize a variety of black bear scats, which can differ considerably depending on what the bears have been eating. “It’s best to train on scats that reflect the diversity of diets—bears can eat salmon, berries, and tubers, and the dog has to recognize them all,” says Davenport.

Training the handler is just as important as training the dog because the pair works as a team. The handler has to both trust the dog and help it search effectively. For instance, if the dog smells a scat but can’t find it, the handler needs to know how to guide the dog. “If there’s a huge patch of blackberry brambles and the wind blows around it in a circle, the dog may run around in a circle too. The handler needs to move the dog past the obstacle by helping it find where the wind comes from before it blows in a circle,” says Wasser.

Dogs are quite adept at finding scat in the field. “They can pick up bear scat from a quarter of a mile away under optimum conditions,” says Davenport. While a dog’s sense of smell is more than 1,000 times keener than a person’s, dogs won’t smell and find everything. “If there’s a strong air current, they can miss scat that is five meters upwind,” she says. Even so, dogs find a lot more scat than people could find on their own. In field tests, trained dogs can find roughly seven out of ten scat samples, which is excellent considering that the wind can’t be controlled, says Davenport.

The Nose Knows
Because scat dogs can get more samples with less bias, the technique could have a tremendous impact on protecting species. “We can gather data we never could before get so objectively,” says Wasser. “It’s hard data about conservation,” adds Wasser, who has been using scat dogs for two major research projects. The first compares black bears (Ursus americanus) and grizzly bears in Canada’s Jasper National Park with those in an adjacent area where there is coal mining, logging, and natural gas and oil extraction. His goal is to see whether these disturbances affect the bears. DNA analysis is used to determine the species, sex, and identity of individual bears, and this information is used to determine the size and distribution of the population. While it’s too soon to say for sure, so far the results suggest that disturbance does affect the bears’ distribution and stress levels.

His second scat-dog project is searching for grizzly bears in Washington’s 10,000-square-mile Northern Cascade Grizzly Bear Recovery Area, about the size of Vermont. Right now there is no proof that any grizzly bears live in this recovery area, which means people could argue that it doesn’t need to be preserved for the species. Indeed, the Plum Creek Timber Company recently won a court case saying that it no longer has to include grizzly bears in the area’s Habitat Conservation Plan.

Wasser has found grizzly bear scat in the northern part of the recovery area. However, this is ambiguous because the scat could be from grizzlies that were just visiting from nearby parts of Canada. “If we find grizzly bear scat in the center of the recovery area, it could totally change conservation in the state,” says Wasser. “Among other things, it will call into question the rulings on the Plum Creek HCP.”

Researchers studying the critically endangered Amur tiger (Panther tigris altaica) in Russian forests have a different twist on scat sniffing—they bring scat to the dogs for identification. The researchers can’t take them into the forest to find scat because the tigers will eat them. “We’ve found that they will go out of their way to catch a dog,” says biologist Linda Kerley, who coordinates the project to monitor Amur tigers, which were formerly called Siberian tigers.

Fortunately, finding tiger scat is relatively easy. The big cats often defecate on trails and other open places because they use scat to mark the boundaries of their territories. It’s also easy to distinguish tiger scats from those of the other local carnivores. For instance, tiger scat is cylindrical and contains hair and bone fragments, while bear scat is usually loose and contains some plant material.

The dog’s job is to identify particular tigers in the population by first smelling the scat sample and then matching it with a particular scat in a reference collection from known tigers. To confirm that the dogs are identifying the scat correctly, each sample is matched to the reference collection by more than one dog.

The researchers identified the tigers in the reference collection with a combination of tracking and scat sniffing. First, the researchers tracked tigers in the snow and both measured their track sizes—which indicate that tigers’ sex, because males have bigger paws—and collected scat along the tracks. Then the researchers used the dogs to determine if scats along tracks in one location matched any of those along tracks in other locations.

By mapping the places where scats from particular tigers were collected, Kerley can determine how many tigers are living in a given area, where they are going, and whether the population’s size is changing. “Monitoring our tigers using dogs is cheaper, faster, and less intrusive than other methods,” she says. “We need to know if our anti-poaching strategies are working. We need to know immediately if tiger numbers begin to decline.”

New areas to sniff
Wasser sees a variety of other ways to use scat dogs. The technique could be a less stressful way of collecting scat from spotted owls in the Pacific Northwest. These threatened birds defecate under their roosts, but their scat is so small that people can take a while finding it, which is stressful for the owls. If dogs could find it faster, it may be less stressful on the birds.

Scat sniffing could even be adapted to studying endangered right whales in the Bay of Fundy in Maine. Researchers go out in boats to collect the whales’ feces, which are bright orange (due to the whales’ krill diet) and float for a while. The problem is that the feces are hard to see when the water is choppy so people can’t always spot them before they sink. Scat dogs could be a great solution to this problem because the whales’ feces are also malodorous—Wasser plans to train dogs to sit in the bow of a boat and point their noses toward the scent. Currently, the researchers manage to retrieve about 40 samples of right whale feces per season and Wasser thinks using scat dogs could bump that number into the hundreds.

Solid information on threatened species can be hard to obtain, making it difficult to justify conservation actions. Scat sniffing—whether on its own or in combination with DNA and/or hormone analysis—could help change that by providing hard evidence about animal populations. “These combined techniques offer a suite of new opportunities to wildlife managers and conservation biologists,” says Wasser.

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Making Connections
Scat Sniffing

—Robin Meadows is a contributing editor to ZooGoer.

ZooGoer 31(5) 2002. Copyright 2002 Friends of the National Zoo.
All rights reserved.

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