Deterring Bats from Transportation Infrastructure: Methods and Results (2026)
Chapter: 5.0 Additional Observations
5.0 Additional Observations
The companion guide (NCHRP Research Report 1166: Strategies for Deterring Bats from Transportation Infrastructure) summarizes data from previous studies documenting the value of acoustic deterrents (including both the BD-100 and systems operated by NRG Systems). Previous studies clearly indicate the importance of acoustic deterrents as a tool for DOTs. Field studies conducted during the current study support what was already known from many years of practical experience—physical exclusion works as long as 1) the exclusion material remains in place and 2) all roosting areas are excluded.
The guide also explores the value of using two approaches in tandem and makes suggestions regarding when one approach should be selected. For example, prioritizing physical exclusion when the goal is permanent removal of bats from a structure. Thus, physical exclusion remains the go-to approach when structures known to contain bats are slated for removal. Conversely, acoustic deterrents are likely most valuable when the goal is a short-term removal with the expectation bats are allowed/encouraged to return. Thus, deterrents appear especially valuable during scheduled maintenance work on a structure known to contain small numbers of common bats. Combining the two approaches appears appropriate when large numbers of bats are present and require removal from an area prior to physical exclusion, when accessibility of some areas makes physical exclusion difficult or impossible, where exclusion material maintenance poses a challenge, and in cases where the presence of rare or protected species requires supplementation of physical exclusion.
Current study data suggest small, low-cost, deterrent devices operable via multiple power sources (including batteries) potentially play an important role in providing targeted or preliminary treatment options when bats are detected immediately prior to planned maintenance or repair activities.
Finally, acoustic deterrence is an area of intense current research, especially in the wind energy industry. In fact, both the BD-100 devices used during the current study and larger systems such as those marketed by NRG Systems were initially designed to prevent bats from striking wind turbines. As this technology continues to evolve, it is reasonable to expect more effective, less technically challenging, and lower cost deterrent devices may be developed in the near future.
