The rickety old cabin known as the Rattlesnake House seemed little more than a scenic remnant of Methow Valley's past. Built some 90 years ago, near Mazama in northern Washington, the cabin had sat empty for half a century — or so people thought.
In fact, the Rattlesnake House was home to a thriving colony of Townsend's big-eared bats (Corynorhinus townsendii), which was using the crumbling cabin as a nursery where females raised their young. Protecting those bats proved a prodigious challenge that ultimately required not only moving the whole cabin, but building a replica of it to convince the bats to make the move. And even then, success was far from certain.
Mazama resident Kent Woodruff, a U.S. Forest Service wildlife biologist and a local authority on bats, discovered the nursery colony about six years ago. While preparing to conduct a workshop on Northwestern bats, he said, “I'd been looking around and stopped in there and found a bunch of bats, both moms and their young. It appeared the bats had been in there for years.”
Townsend's big-eared bats are, Woodruff says, an uncommon species that's found in low numbers from British Columbia to Mexico. The bats are considered a “species of concern,” which means they require concentrated conservation efforts to prevent their decline. The Rattlesnake House nursery colony of 100 to 200 females and their young was an exciting discovery.
A few years ago, the cabin's future was threatened when the property changed hands. However, the new owner agreed to donate the building — provided it could be relocated. So Woodruff came up with a plan to move the 24-by-30-foot (7.3-by-9.1-meter) structure to a new site about a half mile (0.8 kilometer) away.
But he wasn't at all sure the ramshackle cabin would survive the move, so he decided first to build another home for the bats near the planned new site of Rattlesnake House and similar to it in appearance.
“We salvaged old barn boards and materials to put on the new house to make it look and smell and appear old,” Woodruff said.
With a crew of volunteers and financial backing from Bat Conservation International and several other conservation groups and government agencies, work on the new bat cabin began in spring 2001. The goal was to finish the new cabin before the bats disappeared for their winter hibernation. The old cabin wasn't moved until after the bats had left in the fall.
“We wanted to give the bats an opportunity to discover the new bat house [before they left for the winter] so if they returned to the Rattlesnake House and it was gone, they would remember the new house,” Woodruff said. The new house, completed in September 2001, was designed to be more cave-like and inaccessible to other animals so it would be more attractive to the bats.
The old building, laboriously mounted on a truck and semitrailer, was moved in October. After major reconstruction, the roof was finally nailed back on in December, just before the first snowfall. Then it was just a matter of waiting to see if the bats would settle back into their relocated home (or the new house) the following summer.
That spring and summer, Woodruff kept checking the houses, and always he found them empty. “I was pretty discouraged actually. I watched and watched all summer long and for some reason, they didn't show up. I'd pretty much given up and thought, ‘Maybe next summer ...'”
Moving the old house and building a new one were expensive undertakings, and Woodruff and his volunteers had invested hundreds of hours. But he knew all along that success was never a sure thing.
“As biologists, one of the things we know is that we usually can't understand why animals live where they do,” he said. “We only guess at some of the things that might make a particular place suitable to occupy. That's what I was doing. We had recorded thousands of temperature measurements in the old Rattlesnake House to get information about it, and it helped paint a picture of what we needed to do with the new house.”
Before leaving on vacation in August, Woodruff decided to check on the bat houses. This time, when he peered into the Rattlesnake House, he found to his surprise and delight that “it was full of bats.” He beat a quick retreat so he wouldn't disturb them.
The bats remained there for another month before leaving in September. Woodruff initially found two or three bats in the new house and speculated that they were bachelor males, who don't live with the females and babies. By the end of the summer, a female and her pup had moved into the new house.
The old and new cabins are on land acquired by the Trust for Public Land and subsequently sold to a private owner, with the bat-house parcel designated, Woodruff said, “as a non-developable piece of ground. And the new owner is very excited about working with us.”
With the second summer coming up, the waiting game is on again, although Woodruff is more hopeful that the bats will return. If so, the achievement would be considerable: “I am not aware of anyone who has successfully moved a Townsend's big-eared bat colony,” Woodruff said.
“We will really want to watch carefully to see what happens this year,” he said. Will the bats prefer their traditional roost in Rattlesnake House, expand into both houses, or perhaps choose the newer, more secure home? Time will tell.