WINONA — State transportation and wildlife officials in Minnesota and Wisconsin are working to relocate thousands of threatened bats that have been living under a Mississippi River bridge that’s due to be torn down.

Wildlife biologists from both states estimate there are about 3,000 bats living under the Interstate 90 bridge. Wisconsin Department of Natural Resources conservation biologist Heather Kaarakka says the bridge bat colony is one of the largest known in the Badger State.

The 48-year-old bridge is being torn down as part of a three-year, $187 million replacement project.

The Winona Daily News reports the Minnesota Department of Transportation recently installed “bat condos” along the bridge for relocating the colony.

The four-foot-square wooden houses on stilts should provide room for up to 4,000 bats.