Breaking Bad Habits: Bears and Melons
This article is from P&C’s 2020 Fall Newsletter. Read the newsletter here.
By Bryce Andrews
Wild animals thrive in the thickets along the Jocko River. The cottonwoods and brush grow thick beside the river’s course, and the floodplain remains largely undeveloped, thanks to the conservation efforts of the Confederated Salish and Kootenai Tribes (CSKT). The river corridor is of particular importance to the region’s bears—both black and grizzly—which use it to travel between the Mission Valley and habitat located farther south and west.
The Jocko Valley is also essential ground for agricultural producers, who make use of the valley’s low elevation and relatively mild climate. In 2019, People and Carnivores began working with Dixon Melons, a family farm that specializes in growing cantaloupes and watermelon since 1987. The farm had long been losing tons of ripe melons to bears with conflict increasing in recent years, particularly in a twenty-acre field adjacent to the Jocko River. In 2019, Dixon Melons co-owners Cassie and Faus Silvernale estimated that bears consumed 5% of the crop – about 5,000 melons!
After confirming with CSKT biologists that collar data showed grizzlies as well as black bears moving through the area, we started working to build an electric fence around the melon field. Serendipity connected us to the Western Transportation Institute (WTI), which wanted to explore new gate systems to reduce bear-vehicle collisions. Working with WTI, we incorporated a series of electrified ‘drive-through’ and ‘drive-over’ gate designs around the melon field. If the prototypes showed promise, WTI intended to the use similar designs to keep grizzlies and other large carnivores from straying onto highways.
Courtesy Western Transportation Institute-MSU
As the melons ripened, we relied on trail camera data collected by WTI to determine the effectiveness of our experimental barriers. Our data showed two things clearly: First, that the melons were drawing plenty of bears. Second, that those bears were deeply food conditioned and determined to eat. The cameras recorded all manner of ursine attempts to get over, under and through the fence. Many were unsuccessful, but some dedicated bears made it into the field. Working from WTI’s camera data, we fine-tuned our designs to address problems wherever we found them.
At the time of this writing, two-thirds of the way through the melon harvest, the results look encouraging. According to the folks at Dixon Melons, crop loss has been reduced by 80% from the previous year. One of our electrified gates—the ‘drive-over’ design— is particularly promising. It stopped bears in 17 of 18 attempts, with the lone exception being the deviously committed yearling black bear, which managed to cross by carefully placing its paws in spaces between electrified wires. We subsequently narrowed our wire spacing. Your move, yearling.
In the fall of 2020, in partnership with WTI, we will build on what we’ve learned at Dixon Melons by installing two more prototype ‘drive-over’ gates along Montana Highway 93. We hope to see these structures reduce collision rates and keep wild carnivores moving safely across the landscape.
