Sibling scientists and their dog hunt for Oregon’s hidden truffle biodiversity

A wagging tail is the universal sign of one happy dog, especially for rusty golden retriever Rye. It’s his “tell-tail” signal he’s found buried treasure. 

But this treasure is no pirate’s booty. Instead, it’s a prized fungus. 

In an oak savannah just outside Eugene, Rye picked up on a scent and was digging through a frosted pile of dead leaves and grass. His feather duster of a tail is his own proximity detector, swishing faster the more confident he is. But after clearing a couple of inches of dirt, he looked up at Heather Dawson with a plea. Heather, Rye’s handler, knelt and coaxed him to keep trying. This bounty was unusually deep underground. 

After another pawing excavation, a brown, warty lump the size of a fingernail emerged. Rye looked up at Heather again, but this time with a shining example of “puppy-dog eyes.” She brought the prize to her nose but smelled only the dirt it was covered in. Although the smell of nothing sounds boring, when it’s a game of roulette between getting a whiff of lemon bar or rotting onions, it can be a relief. 

“The range of aromas I’ve got to smell, sometimes it’s disgusting. But I have no idea how he smelled this,” said Heather, a doctoral student in biology in the College of Arts and Sciences at the University of Oregon, while examining the seemingly odorless find. “Amazing.” 

Rye uncovered a Genea truffle, an infamously cryptic underground mushroom due to its small size and dirt color. They’re difficult to discern through traditional collecting methods like raking, but for animals with keen noses, a truffle’s aroma marks the spot in an entire forest. 

Scent-detection dogs are widely used by the military to detect illegal goods and by some doctors to sniff out medical conditions. So teaching dogs to find truffles for science is more of a fringe-use case, Heather said. 

But any dog can be trained to be a truffle dog, she said. Canines have been trained to find fungi of culinary and economic value, including Oregon black and white truffles that are grated on top of pasta or infused into oil. Truffles used in the kitchen, however, are a fraction of what’s below the surface. 

Scientists don’t know how many fungal species exist in the Pacific Northwest, where they’re located or what environmental factors affect them, Heather said. She said the biology and ecology of Oregon truffles are largely limited to research done in the mid-to-late 20th century — before truffle dogs were recognized in the United States and before DNA sequencing was readily available. 

“There’s a lack of data on fungi as we’ re not taking care of them in the same way we take care of plants and animals,” she said. “It’s fairly easy to survey plants and animals and get them listed as threatened or endangered. But fungi, they’re just harder to study.” 

You can’t sell biodiversity, but it should be protected, Heather said. Heather Dawson and her sister Hilary Rose Dawson both helped train Rye to hunt a range of truffles — good- or bad-smelling — for science and conservation. 

While some truffles are prized for their flavor and command high prices from top restaurants and chefs, many other varieties are found around the world and play a role in different ecosystems. Many of the ones Rye finds aren’t good eating (for humans, at least), but they’re important nonetheless. 

Rye’s catalog contains more than 50 genera, or broad categories, of truffles since he began searching in 2020. The sisters’ latest data, published in a 2024 paper in the journal Ecology and Evolution, suggests some species of Oregon’s truffles may be affected by warming temperatures and the expanding severity of wildfire season. 

It’s a race against time to catalog those hidden treasures before they’re lost to climate change. 

‘A truffle conveyor belt’ 

Heather has loved fungi since she was a kid. Behind the Dawsons’ childhood home in Massachusetts was a conservation forest where the sisters ran wild, which the pair credits for preparing them for the fieldwork they now do. 

“We’ve done so much backpacking and hiking together that it’s just this natural fit and rhythm,” said Hilary Rose, who earned a doctorate in biology at the UO. “Yes, our personalities can clash. I’m the loud, headstrong one. She’s the quiet, stubborn one. But we have 30 years of knowing that about each other and 30 years to figure out how to solve that.” 

But growing up homeschooled without a formal scientific education, the sisters didn’t expect to pursue paths in biology later in life, especially since their parents weren’t scientists either. It wasn’t until Heather trained her first truffle dog, Cricket, that she saw the potential of making her fungal affinity a real career. 

Heather initially trained Cricket to scavenge culinary truffles by hiding truffle oil and frozen truffles inside and outside her house. Once in nature, the blonde golden retriever was especially good at locating black truffles. But occasionally Cricket would turn up something strange, and that’s when Heather learned that Oregon has hundreds of native wild truffles: a hidden fungal diversity waiting to be understood. 

When Heather got Rye, he was a natural at finding any underground fungi — the sisters call him a truffle conveyor belt. By rewarding him with his favorite ball for new and odd finds, Rye developed a truffle scent library ranging from honey grass to burning brakes. 

“Something in there the dog recognizes as a truffle, whereas my nose can only smell the whole suite of aromas,” Heather said. “That’s what makes dogs so good at finding things: They pick apart all these different components. To Rye, it’s maybe a set of 10 distinct aromas and one identifies as a truffle to him, but to me it just smells like rank, old boots.” 

Oregon’s vulnerable gems 

Rye grew especially skilled at locating Genea, a broad genus of truffles that can smell like a white truffle or sweet like cheese and honey. At the same time, Hilary Rose developed a habit of taking field notes to map their surveys. 

With logs on truffle type, location and weather, she realized that the journal could be turned into a data set. After a year of collecting data across the Willamette Valley, the sisters found that Genea are so prevalent in Western Oregon that they’re essentially as common as the Douglas fir trees they’re attached to. 

They also noticed Genea rarely fruited in burned Douglas fir forests, including areas that experienced wildfire as long as a decade ago. The Dawsons hypothesize that some species of Genea may be vulnerable to fire, a potential problem that’s exacerbated by the threat of climate change. 

That insight likely would not have been as easy to uncover with raking, the traditional, trial-and-error method for digging up underground fungi. 

“I think what’s unique about this data set is that Rye can confirm both presence and absence,” Hilary Rose said. “We trust his nose enough to say that if Rye didn’t find it, then we don’t think it’s there.” 

Yet their surveys, further supported by Heather’s ongoing doctoral research, showed Genea were still fruiting in recently burned oak savannahs. Heather said oaks have adapted to fire disturbance through landscape burning practiced by Indigenous tribes. While oak savannah fires are cooler than conifer ones, no one knows how those fire management practices have affected the habitat’s truffle diversity — especially since truffles grow on tree roots — and whether truffles have adapted to fire too. 

With Pacific Northwest forests facing longer wildfire seasons, Heather plans to investigate how drier conditions are changing the regional fungal ecology and unearth what’s there before it’s lost. 

“When you get these extreme weather events, even being underground isn’t going to insulate you from everything,” Heather said. “If you lose the tree, you lose the truffle fungi living in the roots.” 

Twins two years apart 

This is the Dawsons’ first paper as sibling scientists, together overcoming the scientific skepticism against using truffle dogs for measuring biodiversity. Although well-established in Europe, truffle hunting dogs have been slowly gaining recognition in the states. 

It’s a time-sink to train a dog, Heather said, and it took a while for Cricket to find her first wild truffle. Despite the practice in their home backyard, Cricket wasn’t quite sure what to look for in a forest with hundreds of new scents. 

But on one particular field trip, Cricket was sniffing around and paused at a spot longer than she usually would. When Heather helped brush away the duff to reveal the beautiful black truffle underneath, it all clicked for the canine. 

“Since then, I’ve found more important stuff that I know will make a difference, but I don’t know how much it can beat that first feeling of knowing my dog can find truffles,” Heather said. “It was really special because I had spent so long trying to get to that point that I was having dreams at night of finding truffles.” 

Heather now has funding from the National Science Foundation Graduate Research Fellowship Program and regional mycology grants to work with her truffle dogs to catalog underground fungi in Oregon’s endangered oak savannahs and the Cascade mountains, which include specialized, high-elevation habitats that are especially vulnerable to climate change and extinction. 

Hilary Rose recently moved to Australia, a global hot spot for truffle diversity, and is a postdoctoral researcher at The Australian National University. The wood terrain there isn’t as dog-friendly as the Pacific Northwest, she said. So she convinced herself to buy a rake and found three truffle species the first time she went out raking. 

“There’s nothing quite like going for an underground treasure hunt with a dog and my sister,” Hilary Rose said. “You really can’t top that.”