Evaluating and Improving Current Practices for Temporarily Deterring Bat Use of Bridges and Similar Structures

Bridge repair and replacement projects are required to implement measures to avoid and minimize impacts if protected bats are present. Furthermore, bats across the United States are threatened by a relatively new fungal disease known as white-nose syndrome (WNS). WNS has resulted in bat population declines of over 90% in parts of the northeastern and midwestern United States, and the fungus is continuing to spread westward. These declines most recently resulted in the U.S. Fish and Wildlife Service listing the northern long-eared bat (Myotis septentrionalis) as threatened under the federal 2015 Endangered Species Act, and it is anticipated that additional bat species will be listed in the coming years. Many states have protections for other bat species as well. The northern long-eared bat, as well as other bat species, will utilize bridges and similar structures as day-time and/or night-time roosting habitat, and as places to form maternity colonies where they give birth and raise their young. State departments of transportation (DOTs) can take a number of measures to reduce impacts to bats including timing activities to avoid the season when bats are present; deterring or excluding bats from using bridges and similar structures during maintenance and construction activities; and, in some cases, providing alternate roosting locations. However, timing restrictions can be challenging to implement, especially in parts of the country with long and cold winters and short summer construction seasons. Exclusion and deterrence measures of various types are not always successfully implemented, which can result in work delays if bats continue to use the bridge. Some methods incur higher costs for materials or labor for installation and maintenance than others. This research will focus on strategies and practices for temporarily deterring and excluding bats from using bridges to facilitate construction and maintenance activities, while minimizing harm to bats and non-target species. These may include, but are not limited to, technology such as non-lethal ultrasonic acoustic devices, physical exclusionary devices, and light devices. Providing state DOTs with up-to-date information on exclusion and deterrence measures will make permitting, construction, and maintenance timelines more predictable and easily manageable; provide state DOTs with effective strategies for meeting current and anticipated regulatory requirements for work on bridges and similar structures where bats are present; and afford long-term cost savings for agencies. Further, the research will help state DOTs demonstrate due diligence and interagency collaboration on environmental issues and reduce the transportation sector’s impacts on imperiled bat species. This project will collect information from published literature and from practitioners on currently used and innovative methods for temporary bat deterrence and exclusion from bridges and similar structures to facilitate construction and maintenance activities. A series of regional field tests of specific methods addressing day roosts, maternity roosts, and night-only roosts will be conducted. The field tests will allow for evaluation of the efficacy of exclusion measures on different genera of bats and monitoring bat behavior during the deployment of exclusion methods, as well as assess whether bats return after the exclusion measures are removed. The results will be available at a webpage containing fact sheets on different methods, plan sheets where applicable, a research report, and a handbook for bat deterrence and exclusion from bridges with best practices for implementing different solutions.


  • English


  • Status: Proposed
  • Funding: $500000
  • Contract Numbers:

    Project 25-63

  • Sponsor Organizations:

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001

    American Association of State Highway and Transportation Officials (AASHTO)

    444 North Capitol Street, NW
    Washington, DC  United States  20001

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Project Managers:

    Hartell, Ann

  • Start Date: 20200520
  • Expected Completion Date: 0
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01739655
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 25-63
  • Files: TRB, RiP
  • Created Date: May 18 2020 3:05PM