A rare bird found only in Colorado and Utah could be at risk as the rising rumble of cars disrupts the otherwise quiet sagebrush habitat along a dirt county road now serving as a detour route for the closed U.S. 50 bridge, wildlife biologists say.
A few hundred Gunnison sage grouse, which the U.S. Fish and Wildlife Service listed as a threatened species a decade ago, depend on the sagebrush along County Road 26 to eat, stay hydrated and nest. The road passes through five leks, or breeding grounds, and increased traffic levels could make females feel less safe and choose not to breed, said Nate Seward, a wildlife conservation biologist with Colorado Parks and Wildlife. Some birds could abandon their nests.
Researchers in 2019 estimated that the birds occupied only 10% of their historic range and fewer than 5,000 birds remain. Loss of habitat is the biggest driver of their population decline and if the bridge closure extends several years, the impact on the grouse could be significant, Seward said.
“My biggest concern is that this may not just be a one-year closure or event. I’m concerned that the bridge may be closed for multiple years so I’m anxiously waiting for an engineering report,” he said.
Since the county road opened last month as an option for travelers to get between Montrose and Gunnison without taking detours that added six to seven hours of driving, traffic along the road has increased 40 fold, transportation officials said. A pilot car guides cars across the road four times a day in each direction offering locals relief to get to work, medical treatment and other critical travel.
But if the road becomes a long-term detour, and noise and traffic increases for an extended period, Gunnison sage grouse could abandon their leks and surrounding areas, Seward said.
Past monitoring by CPW and the National Parks Service showed that the females nest very close to County Road 26 under normal traffic patterns and they frequently walk across the native gravel road.
“With increased traffic and noise though, it is more likely that the grouse will be displaced and this could cause a loss of reproduction, recruitment and generational learning,” Seward said.
The ground-dwelling birds don’t adapt well to change and need large undisturbed areas of sagebrush with background noise levels “not much higher than ambient conditions,” he said.
Since 2006, well before the Gunnison sage grouse were federally listed as threatened, Gunnison County officials voluntarily closed County Road 26 during breeding season, county commissioner Jonathan Houck said. Opening the road as a detour was a difficult but “balanced decision” the county made while talking to wildlife officials and the Bureau of Land Management, he said.
“When opening the road, sage grouse was right in the forefront of our decision-making on that,” Houck said.
Gunnison County officials delayed the first time slot for the morning commuters by 30 minutes, giving sage grouse extra time for displaying and breeding before the first line of traffic passes.
The delay ensured that the cars traveling east to west passed through the leks after the sun had already reached them, Houck said, explaining that the birds tend to be in the leks as the sun rises.
There has been mounting public pressure to add morning times, but the county held off considering any additions until at least May 15, when the breeding period typically comes to an end, he said.
“This community is almost 20 years deep into sage grouse conservation. It’s heavily behind it and it’s really important and I think that people understand that balancing act,” Houck said.
“For us to open one of the 30-some roads that we keep closed was a hard decision but one that had to balance that economic need, the emergency need, the wildlife needs. No easy answers here.”
The pilot car helps reduce the impact on the sage grouse by guiding cars at slower speeds and ensuring cars stay on the county road without driving on adjacent public land.
Crews have dumped thousands of pounds of gravel along the 15.5 miles of the gravel road to make durable under the increased traffic.
But improvements to the road could also lead to more cars, higher speeds and greater noise, which would create “a more formidable barrier” for wildlife, like the Gunnison sage grouse, mule deer, elk and bighorn sheep that also use the Spainero Mesa, Seward said.
To reduce the impact to Gunnison sage grouse, Seward suggests using the detour only for emergency or medical treatment.
“Please respect the speed limit, be patient and enjoy the scenery as many of us would not have much reason otherwise to use CR 26.”