A single truck accident wiped out a third of the bighorn lamb reproduction in the lower Rock Creek drainage this summer.

The unidentified Idaho driver collided with seven lambs while driving near the Rock Creek Trout Bums fly shop. A tragedy in itself, the deaths also hammered a herd already halved by a pneumonia outbreak two years ago.

“They were just super frisky, and they played in a group,” said Trout Bums co-owner Deb Peltier. “They came off the mountain racing, like they always do. They were like toddlers – oblivious to everything. When I got there, there were baby sheep laying everywhere like bowling pins. It was a horrible, awful sight.”

It also killed at least a third of the 21 lambs seen in the lower Rock Creek bighorn band this spring. Because bighorns tend to have very poor reproductive success several years following a pneumonia epidemic, Montana Fish, Wildlife and Parks biologist Ray Vinkey doesn’t even include them in his population surveys until they’ve survived through the following spring.

“We’re assuming we’ll lose another seven sheep this year,” Vinkey said. “So a strike like this really has a dramatic impact on a population that’s already compromised by the lingering effects of pneumonia.”

In 2008, the year before the disease hit, the lower Rock Creek band of bighorns had 201 sheep and a lamb-ewe ratio of 44:100. The area was a regular choice for transplant bighorns to supplement populations elsewhere in the West.

The die-off started in the fall of 2009. The following year, Vinkey and other FWP officials shot dozens of bighorns as pneumonia outbreaks appeared in band after band in the Bitterroot, Blackfoot and Anaconda regions, as well as Rock Creek. The culling was intended to slow the disease’s spread, and had mixed success.

Peltier said she still heard a few bighorns coughing last winter – the distinctive symptom of infected sheep. But the hope is most of those still alive are either resistant to the disease or were lucky enough to outlast the outbreak.

Nevertheless, lower Rock Creek now has just 57 observed bighorns 11 months old or older, and a lamb-ewe ratio of 18:100. Losing seven to a road accident brings a special disappointment.

“The main thing is the speed on this road,” Peltier said. “There’s a bottleneck right by us. We’re about 8.5 miles up, between Sawmill Road and Brewster Creek Road, where a good number of them have their babies. They’re here all summer long. They live on the mountain, but they cross the road to go to the meadow to eat.”

Peltier said Granite County sheriff’s deputies told her they’ve often caught motorists speeding 50 mph on a road limited to 30 mph. There are road signs warning about bighorn sheep, but they’re down around mile marker 6, where there’s a wildlife viewing area.

Vinkey said he got commitments from Granite County officials to place sign poles near where the lambs died, and FWP will provide the warning signs.

“It’s a high priority for the county,” Vinkey said on Friday. “We expect lamb production to be suppressed for a few years, and sheep can be in the roads frequently. Motorists need to be aware.”

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