Most Likely Bridges as Roosting Habitat for Bats: Study for Iowa

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Bats play an important role in the natural balance of many ecosystems. There has been a growing concern about the bat population in the United States, mainly because of white-nose syndrome (WNS). The primary objective of this work was to better understand what types of bridges are the most likely to be used by bats as roosting locations. In one of the most comprehensive studies in the United States to date, 517 structures in the state of Iowa were inspected for evidence of bat roosting. Logistic regression models were fitted to identify structure, land cover distribution, and predicted bat species distribution characteristics that increase the probability of bat roosting. The final model indicated that probability of bat roosting on bridges increases under the following conditions: structures are prestressed concrete continuous, prestressed concrete or steel continuous; increased superstructure height above ground; increased superstructure depth; increased wetland coverage within a 0.1-mile radius of the structure; and increased number of potential bat species present at the location. The findings show that bridge characteristics, combined with land cover and bat species distribution data, are significant for higher probabilities of bat roosting. This information can be useful to transportation agencies as they plan bridge maintenance and renewal and can also help conservation efforts targeted toward bats. It is thought that the integration of objective, geospatial land cover data with potential bat presence data, and estimation of quantitative and relative influence of variables on probability of bat roosting are unique to this study.


Mechanical and Civil Engineering

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Transportation Research Record: Journal of the Transportation Research Board