As the quality and quantity of natural roosts such as caves and snags have diminished, the importance of artificial habitats such as bridges and culverts has increased. At this time, over half of the 47 species of bats in the United States have been documented to use highway structures as roosts, including some very large colonies such as the approximately 1.5 million Mexican free-tailed bats that live each Summer under the Congress Avenue Bridge in Austin, Texas.
Although at one time seen as a nuisance, today there is greater understanding that many of these bridge colonies are an indispensable natural resource that can provide important ecological benefits, including pest control. They are also an important tourist attraction. Year after year, the bats at Congress Avenue Bridge help bring to Austin several million dollars in revenues from tourists. In Austin, the public has firmly demonstrated its support for bats in highway structures. Furthermore, research documenting the impact of bats in reducing crop pests is rapidly increasing support in agricultural communities. People support what they value, and the relationship between bats and highway structures is clearly valuable to both humans and bats.
Transportation departments are ideally positioned to help re-establish one of America's most valuable wildlife resources through popular proactive measures. By understanding the construction features and settings which most benefit and attract bat populations, bridges can be designed to provide valuable habitat to declining bat populations, often at minimal or no extra cost. Bridges can also be retrofitted to accommodate various types of bat houses.
Bat Conservation International stands ready to team with private, state, and federal organizations to protect current roosts, promote new roosts, and help partners meet the challenges of managing bridges for bats.
Bats in American Bridges Manual [6.7 mb]
More more information, contact BCI's Artificial Roost Coordinator.