With some bat species, especially in Eastern and Midwestern states, success in mine gating and cave restoration is measured by thousands, even hundreds of thousands of bats that gradually move into a roost. But the yardstick is different in the semiarid expanses of the American West.
Consider the Townsend’s big-eared bat, which forms small colonies, typically fewer than 150 bats, that roost in caves, mines and buildings. Conserving important habitats for this state-recognized Species of Concern requires broad collaboration at numerous roosts.
In the fall of 2003, a BCI sponsored gating workshop in Death Valley National Park that was cosponsored by Rio Tinto Minerals (formerly U.S. Borax), the Death Valley National Park, the California Department of Conservation and the U.S. Bureau of Land Management. Participants built a bat-friendly cupola gate over both entrances to Devil’s Hole #2 Cave in the park. The new cupola replaced a pair of earlier gates blamed in part for a continuing decline of a Townsend’s big-eared bat maternity colony in the cave.
BCI volunteer Mike Rauschkolb of Rio Tinto Minerals led a four-year monitoring project that began at Devil’s Hole #2 just before construction of the new gate. He has now documented a 275 percent increase in the maternity colony – from 20 bats in 2003 to 75 bats in 2006, the largest-known Townsend’s maternity colony in the Death Valley area.
Such systematic monitoring at key bat roosts is an extremely important part of roost gating and restoration projects. It not only documents the success of such collaborative conservation efforts but also provides invaluable data for resource managers if further work is needed.