Deterring Bats from Transportation Infrastructure: Methods and Results (2026)
Chapter: 1.0 Introduction
1.0 Introduction
Bat species in North America face many challenges including habitat loss and degradation, mortality at wind turbines, and disease (especially white-nose syndrome [WNS]). As U.S. bat populations decline, transportation structures such as bridges and culverts offer important opportunities for conservation. Across the U.S., Departments of Transportation (DOTs) manage hundreds of thousands of structures, inadvertently providing habitat for millions of bats. While most structures contain common species such as big brown (Eptesicus fuscus), Yuma (Myotis yumanensis) and Brazilian free-tailed (Tadarida brasiliensis) bats, some harbor rare species including the following federally endangered species: Indiana (Myotis sodalis), gray (M. grisescens), and northern long-eared (M. septentrionalis) bats, and a species proposed for listing, the tricolored bat (Perimyotis subflavus). The conservation value of transportation structures is well-established, but little-known outside of biologists working with DOTs.
DOTs regularly remove bats from structures including bridges and culverts either 1) because bats pose a health or safety hazard to people or 2) to protect bats while a structure is repaired or demolished. Current studies highlight two approaches for DOTs to remove bats from structures. Exclusion refers to physically blocking access to structures or portions of structures via techniques such as applying filler materials. Alternatively, deterrents such as acoustic, light, or wind devices to discourage bat use of structures are also under consideration. Thus, DOTs require implementation of practices to either permanently or temporarily exclude bats from structures. However, detailed data regarding cost and efficacy of various exclusion/deterrent protocols are currently lacking.
National Cooperative Highway Research Program (NCHRP) Project 25-63 facilitates current exclusion/deterrent protocol identification and evaluation through literature review, controlled field studies, and development of a guide to standardize DOT protocols including tools facilitating implementation of recommendations. This document describes the development of the project and the research undertaken.
