BOISE, Idaho (AP) — An effort spanning 31 states and 10 Canadian provinces is working to better understand the ecological role that bats play, and the threats they face from climate change, habitat loss and wind energy development.

The North American Bat Monitoring Program involves acoustic surveys to detect the high-pitched frequencies emitted by the flying mammals as they capture bugs and navigate in the dark. Researchers say the monitoring program has been spurred by a disease called white-nose syndrome that has killed millions of bats and is spreading.

North America has some 150 species of bats, 47 of them in the United States. Some migrate more than 500 miles, and others hibernate in caves or abandoned mines. Less than a handful of bat species are well understood.