Guest blog: NPS technician Shawn Thomas listens to bats at Lava Beds National Monument

Researcher holding a Townsend's big-eared bat. Photo credit: Ann Froschauer/USFW

Lava Beds National Monument in northern California is a hotspot for bats, with both high diversity (14 bat species) and abundance (thousands of individuals) of bats making use of the monument. The presence of so many bats is due to the wealth of habitat – with hundreds of caves to choose from, bats can be selective and find specific caves that suit differing maternal (summer) and hibernacula (winter) needs.

For years, Lava Beds staff have searched for Townsend’s big-eared bat (Corynorhinus townsendii) colonies in the summer and counted these bats as they hibernate in the winter. Recently, though, we have begun augmenting these efforts with the use of acoustic bat monitoring technology which will allow us to learn about other bat species in the monument. Acoustic monitoring has become a leading method for the study of bats due it being a highly efficient and non-intrusive means of collecting data on bat activity. As bats forage at night, they use echolocation for navigation and hunting, and we are using bat detectors which record these ultrasound frequencies that are not audible to the human ear. Specialized software can be used to view the bat calls, and in some cases, the characteristic shapes and frequencies of the calls can be used to identify bats to the species level.

We are hoping that by implementing long-term acoustic monitoring we will be able to characterize the occurrence and activity levels of our bats on a park-wide scale. In the process, we will also gain new knowledge on bat species that are present in Lava Beds but which we rarely encounter in caves, such as the little brown bat (Myotis lucifugus) and other species of the Myotis genus. This knowledge could serve as a baseline for determining the impact of white-nose syndrome in the event that it reaches the western United States. Additionally, this acoustic data can be analyzed to determine seasonal patterns in bat activity, which may reveal the timing of when bats go into and out of hibernation and contribute to understanding how the life cycles of bats may be influenced by environmental triggers. We are also collecting acoustic data from our migratory Brazilian free-tailed bat (Tadarida brasiliensis) colony to learn about the timing of the spring arrival and fall departure of the colony. Our acoustic monitoring efforts are largely in a pilot phase this year, and we are still refining our protocols, but we hope to fully implement our acoustic program in 2012.

Shawn Thomas works as a Physical Science Technician at Lava Beds National Monument in northern California, where he has been stationed since 2009. He is part of the cave management program at Lava Beds and supports a variety of projects in the Resource Management Division. Shawn’s primary focus is on bat monitoring and bat management, and he serves as the monument’s representative in collaborating with agencies and researchers on white-nose syndrome and bat research.