Nate Breece rappelling into a mine shaft. Bishop, California
Priyesh Patel

Assess and protect subterranean features for bats and their roosting habitat

Our Subterranean Team works closely with federal, state, and private land managers to identify and evaluate abandoned mines serving as bat roosting sites. The estimated 500,000 abandoned mines throughout the United States present many potential dangers to human health and the environment; therefore, State and federal government agencies are tasked with reclamation and closure of these hazards through abandoned mine land (AML) programs. Yet many of these abandoned mines have become significant habitat for bats as they seek refuge from encroachment by human development.


Work closely with state and federal agencies and private industry
Survey abandoned mines for signs of bat use
Provide guidance on installation of bat-compatible gates at mine entrances

Project Details

BCI partners with agencies including the Bureau of Land Management, U.S. Department of Defense, U.S. Forest Service, National Park Service, and state AML programs to identify significant bat habitat and ensure long-term protection. On average, our Subterranean Team members spend two weeks of each month in the field conducting biological surveys and mapping underground abandoned mines to assess bat habitat and recommend long-term protection of important bat roosts.

Our abandoned mines initiative is a long-term plan with enormous benefits for bat populations. We survey mines internally and identify features that represent significant habitat and/or contain evidence of bat use. We then make specific management recommendations for each mine and protect important bat roosts while keeping people safe from harm. Since the launch of our abandoned mines initiative in 2008, we have surveyed more than 8,000 mines. Over the next five years we are committed to surveying and protecting an additional 2,500 subterranean features that provide bat habitat.

Dillon Metcalfe looks for bat signs at a junction of mine drifts. Death Valley, California Shawn Thomas

Why Mines?

Bats are attracted to mines because they mimic the safety and unique conditions of cave environments:

  • Mines may offer consistent temperatures and humidity that bats prefer for critical roosting periods such as giving birth to their young and hibernation.
  • Mines are often located in remote areas away from human development and typically experience low human disturbance.
  • Mines are abundant, widely distributed, and offer a range of physical conditions, making them critical components of the roosting landscape.

Jason Corbett conducting internal survey. Mansfield Canyon, Arizona Bill Hatcher

Key Issues

  • Poorly conducted or inappropriate surveys, exclusions, and closures of mines put bats at risk of losing a roost or being trapped alive.
  • Abandoned mines represent a significant liability to owners and land managers; thus abandoned mine lands (AML) closure programs exist to remove the threat from the landscape. AML programs that do not operate in a bat-friendly manner risk destroying roosts and the bats that call them home.