Evaluation of providing bat habitat on transportation structures

Focus Area

Wildlife & Ecosystems


Natural Resources






1-2 years

Research Idea Scope

Bat populations that hibernate in colonies in caves and mines are in steep decline across the U.S. due to white nose syndrome. Loss of summer roosting habitat can exacerbate the decline. Many bridges that currently provide roosting habitat are reaching the need for rehabilitation or replacement and new designs may not include similar roosting habitat. Box beams and expansion joints are commonly used as roosting habitat due to the combination of favorable physical features such as gap size, the open canopy in road corridors and thermal mass characteristics of concrete or steel structures. New bridges are often constructed with prefabricated concrete structures that lack the favorable physical features, but retain the thermal characteristics necessary for bats. A low cost approach to replacing bat habitat would be to attach bat houses to new bridges, but the precise placement and configuration of the bat houses for optimal use is unknown. Additionally, it may be that different species of bats would prefer different placement. The proposed research would explore the feasibility of incorporating artificial roosting habitat into bridges, i.e., removable box-like structures that do not contribute to the structural integrity of the bridge. Some state DOTs have already experimented with artificial bat caves on bridges and it would be beneficial to consolidate the information, analyze their use by bats, and propose standard designs and suitable locations for placement on bridges. Bat box construction on or near bridges could mitigate for loss of roosting habitat while avoiding conflicts with future maintenance activities. Research Objective: To develop a set of best practices for transportation practitioners to assess the value of providing bat habitat on transportation structures. • Synthesize the available literature on creation, maintenance and success of bat roosting habitat, and contact bat experts, non-profits and state transportation departments to determine the current state of the art in creation of bat roosting habitat relative to structures commonly used in transportation settings. • Develop a guide for decision making considerations for the value of providing bat roosting habitat in the transportation setting. • Develop a set of best practices for evaluating and mitigating loss of bat roosting habitat in structures for use by transportation practitioners. **Note – this is a combination of ideas submitted in 2013 and 2014 by Chris Maguire, Oregon DOT, 503-831-3665, [email protected] (TERI 934) and Jason Mays, USFWS, 828 258-3939, [email protected] (TERI 861)***

Urgency and Payoff

There is significant concern about the lethal effects of WNS on bats and the speed at which this infection is making its way across the United States. Some predict major biological and economic impacts as bat populations crash. More bats are being listed under the endangered species act. DOTs are in an unique position to assist fragile bat populations by incorporating bat habitat (i.e., artificial caves) into bridge designs. By designing bat habitat into bridges, not only are we providing bat refugia, but we can direct bats to bridge areas that will not conflict with operational or maintenance actions.

Suggested By

Kris Gade Arizona DOT 602-292-0301

[email protected]