TEN years ago, Louise Wilson gave up a job in marketing to train sniffer dogs. It was a bold decision. This is a male dominated, ex-military oriented world, and the man who is now her boss, a former Royal Air Force dog-handler himself, had originally scoffed at her chances of breaking in. But Wilson was determined. What’s more, she had revolutionary ideas. Not content with training dogs to sniff out explosives, drugs and bodies, as most handlers do, she was eager to test their potential in a new arena – wildlife conservation.
At Wagtail on the beautiful Mostyn country estate in north Wales, UK, Wilson is working with a lithe black Labrador called Luna to find pine marten scat. When Luna sniffs out such droppings, she stops wagging her tail, lies down and her body tenses. Dog and trainer are preparing for an unusual mission. Later today Wilson will take Luna over the border to England to seek out scatological evidence of the elusive English pine marten, an animal known only from museum specimens.
Wilson also has a springer spaniel that she has trained to detect bat carcasses at wind turbine sites and a German shepherd that locates dormouse nests. Two more of her protégés – another Labrador and a cocker spaniel – are already working in Gabon, West Africa, detecting leopard skins and pangolin scales and sniffing out illegal shipments of ivory. If all goes according to plan, they will soon be joined by two more dogs, trained on the scents of shark fins and primate meat, to help prevent illicit trafficking.
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Video: Watch a dog sniff out smuggled animals
Before our outing with Luna, Wilson takes me to the kennels and unleashes five energetic dogs into a field, where they charge around like things possessed. Bradley, a heavy-set springer spaniel who repeatedly crashes into my midriff, is trained to find explosives. He was given up by owners who could not handle his antics. Springer spaniel Levi is a top tobacco-detection dog. He was also brought to Wagtail because of his behavioural problems. “Levi would be a difficult pet. He has issues and possibly obsessive-compulsive disorder,” says Wilson. “If he didn’t have the focus of working and 12 hours activity a day, he’d possibly self-harm.” Their kennel-mate Grace started out as a pet too, but was donated because she chewed walls.
Meeting this enthusiastic and motley crew, I wonder what makes for a good sniffer dog. Are there certain breeds that perform best? Does it take a particular personality? Might my pet pooch have the potential to be a champion sniffer?
People can have strong opinions about which breed to choose, says animal behaviourist Clive Wynne at the University of Florida in Gainesville, “but the scientific evidence is amazingly thin, considering the stakes involved in, say, landmine detection”. Generally, handlers choose working breeds like cocker spaniels, Labradors, German shepherds or Belgian malinois. But when it comes to the all-important nose, no breed stands out (see “A nose with attitude“). In fact, there is scant evidence for significant behavioural differences between breeds: just a handful of studies report differences in performance on cognitive tasks. One test of trainability did find , although in both breeds, field-trial dogs were found to be smarter than show dogs.
The “work ethic” of working dogs makes them an obvious choice, but other breeds may perform equally well, and mongrels can make excellent recruits too. Breed is not nearly as important as individual characteristics. What trainers really covet is a specific personality type. “The dogs we need are highly motivated, and what some might call naughty or mischievous,” says Wilson. “They might be stealing socks and knickers from your bedroom.” It helps if they are also borderline obsessive-compulsive in their desire for a ball, because this is their reward. Wynne has collaborated with a dog trainer who toured local animal shelters with dog toys to see which individuals were best motivated to play; the trainer’s top sniffer is a Chihuahua.
“Good sniffer dogs are highly motivated and what some might call naughty or mischievous”
Such traits are rarely bred into dogs, so finding that special one is not straightforward. People may have dogs suited to sniffer work at home, says Bart Rogers, a handler at the Canine Detection Research Institute (CDRI) at Auburn University in Alabama. A hyperactive pet could have what it takes, but in the pet population you might get just three or four suitable recruits per 1000 dogs. To improve the odds of getting individuals with potential as sniffers, the institute runs a breeding programme using proven pros, including Labradors that formerly worked for Australian customs.
After my tour of Wagtail, I travel with Wilson and Luna to the Shropshire hills in search of English pine martens. Set loose in conifer woods, Luna dashes off into the brush, tail wagging incessantly. Wilson watches her intently and Luna regularly throws her head back over her shoulder to observe her handler. Luna knows that if she finds her target she will get the sniffer dog’s ultimate reward – a tennis ball. It may seem like they are short-changed, says Paul Waggoner at the CDRI, but you must look beyond the ball. “You’ve got the excitement of the handler, the interaction with the person, and perhaps an opportunity to run and play.” Dogs will go to enormous lengths, and distances, for the chance to immerse themselves in such bliss.
Luna has barely put a foot wrong so far on the trail of pine martens: lab analyses of her scat findings to date have been either positive, or occasionally lacking enough DNA to be conclusive. Like all sniffer dogs, she is highly discriminating. If she were trained on just one scat, she would detect that individual pine marten, so to give Luna a wider knowledge of pine martens, Wilson used scats from Irish, Scottish and captive pine martens.
The CDRI has a dog that can distinguish between the droppings of striped skunk and eastern spotted skunk. Dogs can also learn to sniff out a variety of targets. Twister, Wilson’s dog that seeks out bat carcasses, was originally trained to find human cadavers and will now indicate the presence of either type of body. Rogers’s dog, Jake, finds white-tailed deer fawns in Alabama and invasive Burmese pythons in the Everglades of Florida.
Watching the detectives
Although sniffer dogs have been used for decades to sniff out drugs and explosives, they have attracted surprisingly little scientific research. “Canine detection has been practised as a craft, with information handed down from master to apprentice,” says Waggoner. He and his colleagues at the CDRI are among a new breed bridging the gap between canine research and practical dog detection work. In an attempt to find out how sniffer dogs learn to identify new smells, they tested some of their dogs with mixtures of 10 to 20 compounds. Further tests determined that the dogs were using just one, two or three of the constituent compounds to identify any given mixture. However, different dogs focused on different compounds. Recent may go some way to explain this.
Recently, Waggoner’s team discovered that eating less protein and more fat improves a sniffer dog’s detection abilities. On a diet high in corn oil, dogs seem to be better at detecting bomb-related substances such as ammonium nitrate and TNT, possibly because polyunsaturated fats improve the functioning of smell receptors, or perhaps because they reduce body temperature, which in turn reduces panting, improving sniffing. Zinc nanoparticles sprayed in a vapour could also help a dog detect extremely faint odours. “MRI scans showed that parts of the dog brain increase their activity when these zinc particles are present,” says Waggoner. A previous study by CDRI researchers revealed that zinc nanoparticles increased the olfactory response of receptors to odours in rodents.
Fitness is also crucial for olfaction. Dogs can either sniff or pant, so . Not only that, dogs tasked with conservation must be able to run 15 kilometres a day when working, so at the CDRI they are trained for stamina in much the same way as human athletes.
When we stop for sandwiches, Wilson removes the yellow harness from Luna. This signals that it is downtime and Luna takes a standing break, then saunters around. When the harness goes back on, she knows the search has resumed and off she dashes. A talent for responding to such cues is one reason dogs are so trainable. They are particularly good at reading body language. “Dogs are attuned to our movements, our gestures – especially ones we habitually use,” says Alexandra Horowitz, a dog cognition scientist at Columbia University in New York. Pointing gestures are easy for dogs to interpret, but they can also be guided by someone bowing, nodding or turning their head. , and even .
Dog trainers often video themselves at work to ensure that a dog is not picking up on the wrong cues. In training, you might inadvertently drop a shoulder in anticipation when you see the dog approach the target item, says Wilson. That could make the dog indicate at the right spot but for the wrong reasons. “I have to keep moving too,” she adds. “If I stand still in a certain way it might cue Luna to indicate.” It became clear to Wilson just how easy it is to send the wrong message when, during Luna’s very first operational scat search, she ignored obvious pine marten scat on the trail. Wilson’s mistake had been to train Luna to find hidden samples only. She soon put things right. Waggoner describes such unintended cueing by handlers as “an extraordinary problem”. It is always a battle to have dogs under the control of odour and not a range of other cues, he says.
All this helps explain why training a sniffer dog can take up to six months and why many recruits don’t make the cut. Even with a selective breeding programme, the success rate at the CDRI is about 60 per cent. As a result, sniffer dogs command hefty prices, selling for between $20,000 and $30,000 in the US. That may be within the budgets of the military and police, but cost is more of an issue from a conservationist’s point of view. When Dave Goulson at the University of Sussex tried using dogs to locate bumblebee nests, for example, he found it costly and not particularly effective and so ended up recruiting students to seek out the pollinators instead.
Other ecologists also doubt the effectiveness of dogs for conservation work. However, studies in Portugal for bird-strike estimates at wind farms found . In the US, sniffer dogs trained to detect the millimetre-sized scats of the endangered San Joaquin kit fox found four times as many samples as skilled naturalists did. And DNA tests on 1298 scats showed that . Apparently the distinction was as obvious to them as distinguishing between apples and oranges is for us.
Wilson says another big benefit of using sniffer dogs for conservation work is that you can survey without disturbing an animal. She is hoping to train a dog to indicate the presence of great crested newts, a protected species that is usually surveyed by searching for the animal or its eggs during the breeding season when it is particularly vulnerable.
It is early days for conservation hounds but achievements are already stacking up. Rogers recently discovered a probable roost site of the rare Florida bonneted bat after a 21-day search. When his dogs indicated a site close to an old pine tree, near an ant mound, he could find no trace of droppings. “Later that night I remembered that during training, ants sometimes took off with the guano we used,” he says. So they went back early in the morning and, sure enough, bat droppings were present.
In the jungles of Argentina, ecologist Karen DeMatteo of the University of Missouri in Columbia has used her dog to survey four species of cats – jaguar, puma, ocelot and oncilla – where the presence of people makes camera traps impractical. In southern Spain, sniffer dogs have joined a specialised unit set up to detect illegal wildlife-poisoning in the mountainous region of Andalucia. . Wilson believes they could even help curb the spread of diseases such as ash die-off by sniffing out affected trees.
Today has not been so successful. After 3 hours, Luna has found no trace of an English pine marten. Although her tail wags a little slower, she is unfazed and continues her scat hunt past the last conifer, having paid no heed to the droppings of fox, badger or anything else along the way. Finding evidence of an animal that many people believe to be extinct was never going to be easy. But Luna will return to sniff another day.
A nose with attitude
A dog’s sensitivity to odours is staggering. Dogs can detect n-amyl acetate, which smells like apples and bananas, at just 1.1 to 1.9 parts per trillion. That is the equivalent of a pinch of sugar in a billion cups of tea. . No wonder. The olfactory surface within a dog’s nose can measure more than 150 square centimetres and contain up to 300 million olfactory receptors.
Breeds vary (see diagram) but all canine noses are impressive compared with the measly 5-square-centimetre surface area and 6 million receptors in human noses. What’s more, the olfactory area of a dog’s brain is proportionately about 40 times as big as ours, accounting for about an eighth of its total brain mass, compared with less than one-hundredth for us.FIG-mg29311401.jpg
Despite all this, it is not their noses that make dogs such good sniffer-animals. “The odour-guided behaviour and abilities of dogs are no more extraordinary than those of a rat or a mouse,” says Paul Waggoner of the Canine Detection Research Institute at Auburn University in Alabama. “But dogs come with a unique social relationship with humans and they are amenable to do tasks that we want them to do. They want to please us.” Most dogs do not possess other qualities that mark out a prize sniffer (see main story) but all can learn to detect new smells and will improve with training. So if you want to try odour training with your pet, go ahead. Even if Fido doesn’t have a talent for it, you should both find it stimulating.
This article appeared in print under the headline “The nose knows”
