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Eradicating weeds one woof at a time

Is our best defence against pests and diseases to smell them out?

You’re probably used to seeing sniffer (or detector) dogs in airports or music festivals, where they’re trained to sniff out illegal products such as drugs and foods.

Well, it turns out that their super sense of smell can also help protect Australia’s agricultural industries and natural environment.

And the dogs are willing to do it for the simple reward of playing with a tennis ball.

Around the country dogs are being trained to sniff out threatened species such as koalas and quolls, and to identify threats such as the vine disease phylloxera and noxious hawkweeds.

But how good are they?

Missy the weed-detection dog. Picture: Cindy Hauser.

Whether a dog’s job is to detect drugs, droppings or plants, the first phase of training exercises is very similar. However, detecting that same trained scent in the wild can be much more variable and challenging. A large crop field or national park could be filled with all sorts of other distracting and tantalising odours. Changing winds can whip the scent around on a whim. Thick vegetation is hard work to scamper through and may even trap scents in away from the open air.

It’s no wonder that a well-trained detector dog might occasionally miss its target.

My research identifies what we can detect and what we miss when we go out into the field with observational tools - human eyes, DNA testing of water samples, motion-triggered cameras, or, in this case, a dog’s nose. I share my mathematical detection models with government agencies to help them avoid missing what matters most – like hawkweed.

Native to Eastern Europe, several species of hawkweeds have entered the Alpine National Park as escapees from garden plantings in Falls Creek, and possibly also hitchhiking on ski machinery or on the boots or tents of hikers.

If hawkweeds are allowed to spread uncontrolled they have the potential to affect over $1 billion of Australia’s agricultural value, as well as crowding out our native flora in the National Park.

But the good news is that the Victorian and NSW governments, with the help of a dedicated group of volunteers, have managed to prevent hawkweed from spreading. With a little more effort they may be able to completely eradicate these weeds.

You might say we have a sniff of success.

My research tests how good detector dogs are at sniffing out hawkweeds under a variety of conditions.

Detector dogs must navigate complex habitats and changing weather. Picture: Cindy Hauser.

During initial trials in the Alpine National Park, my team laid out a series of hawkweed hide-and-seek games to measure what hawkweed-hunting dogs like Missy (pictured) can do. A GPS strapped to her harness keeps track of her search path, and we time how long it takes her to find each plant. Later on, a map of the full course shows us which hawkweeds she missed.

We can then use statistical analysis to pick out common patterns. We can see whether particular plant types, terrain or weather conditions are particularly difficult for Missy to work through.

One trial in our January 2015 study, in which Missy (solid purple line) and her handler (dashed black line) search for hawkweeds through a mosaic of three vegetation types (grey background shading). Missy signalled on eight of the 21 hidden Hawkweeds, and two of the four non-hawkweed ‘controls’ or decoys. Only a full statistical analysis can reveal whether she signals on hawkweeds more reliably than on decoys. Picture: Cindy Hauser.

I recently won a 2016 Science and Innovation Award for Young People in Agriculture, Fisheries and Forestry, sponsored by CSIRO Health and Biosecurity. It will allow me to continue this research with two more dogs, whose training has benefitted from what was learned during the initial trials with Missy. I will compare their efforts to what we already know human searchers can achieve.

Volunteer teams have spent more than a decade searching for hawkweeds in the Alpine National Park and we know they have a sharp eye for the plants’ distinctive orange and yellow flowers. But in the many months that hawkweeds don’t flower, a dog’s nose probably knows more.

My research enables us to bring out the best in Missy and other detector dogs.

It will help trainers and land managers to create the best conditions for dogs to sniff out their targets, ensuring they’re alert and healthy, and giving them the extra time they need to do the toughest jobs thoroughly.

Banner Image: Missy the hawkweed-detector dog on the hunt. Picture: Cindy Hauser.

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