MONMOUTH, Ore. — Ruby raced through high pasture grass, nose to the ground, searching for the scent of an active vole tunnel.
When she found it, she sat down to alert her handler as more than 40 participants at the Voles, Dogs and Raptors Field Day cheered her on.
Nearby, Reacher — a blue heeler well practiced in detecting vole scent — moved methodically through the pasture, locating active burrow entrances.
A regional vole irruption from 2018 to 2021 caused widespread crop damage and spurred new Extension research into canine detection and control. The workshop also highlighted natural predator support as a tool for reducing vole pressure.
Voles are common in Western Oregon grasslands and, along with pocket gophers, can cause significant damage to crops, orchards, vineyards and pastures. In low-population years, identifying which burrows are active is difficult and expensive, making trapping less efficient for farmers.
Ruby and Reacher have been trained to detect active tunnels to improve trapping success. Their work was featured at the April field day hosted by the Oregon State University Extension Service at Double J Jerseys, a certified organic dairy farm in Kings Valley.
Participants learned about vole ecology and population cycles. A regional vole irruption from 2018 to 2021 caused widespread crop damage and spurred new Extension research into canine detection and control. The workshop also highlighted natural predator support as a tool for reducing vole pressure.
“Voles are a concern because they are a grass-eating animal that also burrow,” said Dana Sanchez, OSU Extension’s wildlife specialist and professor in the Department of Fisheries, Wildlife, and Conservation Sciences. “They have quite an impact on multiple crops up and down the Willamette Valley.”
Training dogs to improve detection
Sanchez has been collaborating with Nick Andrews, Extension organic vegetable crop specialist, on canine-assisted vole detection.
“About four or five years ago we went through a major vole irruption in the Willamette Valley,” Andrews said. “All of the vegetable farmers I was working with were struggling.”
In 2023, Andrews, Sanchez and Jenifer Cruickshank, Extension’s statewide dairy cattle specialist, received a grant from Western SARE (Sustainable Agriculture Research and Education) to evaluate whether trained dogs could help organic farmers more efficiently identify active vole tunnels.
“I’m working with organic farmers. They can’t use zinc phosphide rodenticides to control rodents,” Andrews said. “The dogs are making the searching a lot more effective.”
At the field day, Reacher’s handler, Susie Dunham, demonstrated how he identifies active holes. After confirming the scent with a jar of freeze-dried voles, she walked with him across the pasture, where he indicated live vole activity by stopping and sitting.
Following detection, Extension faculty research assistant Cora Bobo-Shisler demonstrated trapping techniques. She showed how to block nearby exit holes with burlap, place paired traps in runways adjacent to active tunnels and cover the traps with waxed cardboard “tents” to protect non-target wildlife — a method preferred by organic farmers.
Encouraging natural predators
Before the field demonstrations, participants gathered in the barn to hear from Sanchez and Cruickshank. Many attendees — from viticulturists to vegetable farmers — described their own vole challenges.
Raptors are natural vole predators and can play a role in control efforts, said David Wiens, a wildlife biologist with the U.S. Geological Survey in Corvallis. He discussed regional raptors that can be encouraged through habitat enhancements such as perches or nest boxes.
Owls, kestrels and hawks all feed on voles and can help reduce populations in fields.
“Adding back in habitat for animals like raptors and owls can help take some of the voles out of the system,” Sanchez said.
Jon Bansen, owner of Double J Jerseys, worked with Andrews to install raptor perches along a fence line in April. Game cameras set up before the workshop recorded frequent activity: 11 red-tailed hawk visits, 21 kestrel visits and two great-horned owl visits. Taller perches appeared to attract slightly more use.
Henry Sullivan, a mixed vegetable organic farmer in Hillsboro, said vole damage once led him to stop planting beets. After installing irrigation risers as perches about six months ago, he has noticed more kestrels in his fields and hopes to expand raptor habitat.
Continued research
Extension researchers continue to study multiple tools and techniques to support farmers as vole populations rise and fall over time. The long-term goal is to help growers prepare for the next inevitable population spike with effective, low-impact management strategies.
Previously titled Dogs sniff out destructive voles to help farmers with control
