Wildlife experts in US west have found small aircraft are ideal for protecting humans and livestock from predators
The first time that Terry Vandenbos watched a bear run from a drone, on a spring day two years ago, he was chasing the animal himself. After he saw the grizzly cross a road near his property, the Montana rancher hopped on his all-terrain vehicle, planning to scare it away from his cattle if needed.
But the bear began sprinting away when he was still far from it, looking over its shoulder as it ran, and Vandenbos looked up too; overhead, a small drone was following the bear, its four propellers emitting a high-pitched whine as it sent the animal towards a nearby lake.
“I don’t think I need to be here,” Vandenbos remembers thinking. He drove back home. The bear never touched his cows.
On the other end of that drone was Wesley Sarmento, a grizzly bear management specialist for Montana’s department of fish, wildlife and parks (MFWP) who has spent the last six years testing different non-lethal methods for scaring bears away from human habitation, a practice commonly referred to as “hazing”. In research forthcoming in the journal Frontiers of Conservation Science, Sarmento – a PhD student at the University of Montana – shows that aerial drones outperformed all other hazing methods tested in his experiments. They provide a way to move grizzly bears away from humans that is safe for humans and animals alike.
“The drone’s become a tool where I can’t see doing the job without it now,” Sarmento said. “It’s just that handy.”Increases in human-wildlife conflict
For nearly two centuries, prairies like those around the Vandenbos farm in north-eastern Montana have been nearly free of large predators. As humans converted native grasslands to farms, they also waged a highly successful campaign to shoot, poison and drive away animals like grizzlies, wolves, coyotes and mountain lions. But in the last 50 or so years, that has changed. Thanks to laws like the Endangered Species Act and a growing awareness of predators’ important roles in the ecosystem, predator populations have regrown.
“The really good news is that we’ve done a good job of recovering some of our large carnivores,” said Julie Young, a wildlife biologist at Utah State University studying how to reduce human-wildlife conflict. “At the same time, the human population increased when carnivores’ were at their lowest. We didn’t think about how to live with them because we didn’t have to.”
As returning predators find their former habitats occupied, conflicts are increasing. Between 2013 and 2021, cattle lost to grizzly depredation in Montana increased from roughly 20 a year to more than 140 a year, according to the most recent statistics available from MFWP. Grizzly populations are growing in Idaho, Wyoming and parts of Washington state.Seeing what sticks
MFWP hired Sarmento in 2017 to help deal with these growing conflicts. Locals in the agricultural hub of Conrad were told to call the grizzly management specialist if a bear entered their property to scare the animal away. In his early years on the job, Sarmento focused on using his truck to scare bears off, driving toward the animals and honking his horn, as well as firing non-lethal firearms like rubber bullets, loud cracker shells and paintballs. He also persuaded the US Fish and Wildlife Service – which manages grizzly conservation, due to their endangered status – to give residents permission to use paintball guns and their own vehicles to scare bears away themselves if his team couldn’t be there in time.
Sarmento found that these techniques had their limits. Projectiles usually drove bears off but required getting close to the animals; rubber bullets also posed a risk of injuring, and even killing, bears if not used correctly.
