Anne Ruggles, of Bear Canyon Consulting, marks a male Preble&#8217;s meadow jumping mouse for identification purposes Boulder open space along South
Anne Ruggles, of Bear Canyon Consulting, marks a male Preble's meadow jumping mouse for identification purposes Boulder open space along South Boulder Creek in 2013. ( JON HATCH )

The flood has long since subsided, but it still will be months before experts know the impact of September's rains on one of the area's most vulnerable inhabitants -- the Preble's meadow jumping mouse.

The Preble's mouse is a threatened species under the Endangered Species Act -- and that's during the best of times. September, when well over a foot of rain fell in many areas along the Front Range in a week's time, was tough on many species.

But for the Preble's population, the storm likely was particularly hard. The mostly nocturnal mouse typically favors heavily vegetated streamside areas and the immediately adjacent upland areas along the eastern edge of the Front Range foothills from southern Wyoming to south of Colorado Springs.

The South Boulder Creek drainage has been designated by the U.S. Fish and Wildlife Service as a "critical habitat" to the Preble's mouse, meaning that it is considered essential to the conservation of the animal, and may require special management considerations or protections.

"We know a lot of habitat was destroyed -- not just on South Boulder Creek, but the St. Vrain, the Big Thompson, the Cache La Poudre," said Susan Linner, a Colorado field office supervisor for the U.S. Fish and Wildlife Service, based in Lakewood.

"The good thing is that it happened in early September," she said. "Preble's is a hibernating species, but they wouldn't have been hibernating at that time. I'm sure there were some that were caught up in the flooding, but our expectation is that some were able to move away and hopefully find some suitable locations to hibernate."

But because the mice would have subsequently gone into hibernation last month, she said, there's no way right now to assess the population, post-flood.

"So we really won't know until next spring, and until we can do some mapping studies, what the population status is," Linner said.

Some wildlife advocates in the wake of the flood expressed concern about other small wildlife, particularly prairie dogs and burrowing owls. Experts believe fears about those species are largely unfounded.

"There were certainly some prairie dogs that were lost in the flood, but there were a lot of areas that even had water running across them during the storm that had prairie dog burrows, that are active now," said Janet George, a senior wildlife biologist for the Colorado Parks and Wildlife northeast regional office.

"They have a fairly high reproductive rate, so they bounce back pretty quickly, too."

As for burrowing owls and other birds that nest in or close to the ground, George said, "The timing of the flood came long after the nesting season, and after the point where the young of the year could fly. So there would be very minimal losses, if any."

George added, "There may be some individual cases where burrowing owls may have lost an actual burrow to use next year, but there are plenty of other burrows around, and they can adjust. And we have not found any sites that were active before, that were lost."
