PS 23-70 - Detecting bridge-roosting bats with eDNA: Preliminary results

Abstract: In human-modified landscapes across North America, bridges can provide bats with an adequate alternative to natural roosting sites. However, as critical infrastructure, bridges must be repaired or maintained regularly to ensure their integrity and ultimately the safety of pedestrians and vehicles. These construction activities can cause significant disturbance or mortality to bridge-roosting bats. Federally and in some U.S. states, legislation requires the inspection of transportation infrastructure prior to construction to determine if bats are present. Current survey methods, however, are time- and labor-intensive. A promising approach for improving the detectability of bats roosting in bridges is through environmental DNA (eDNA) analysis. However, eDNA approaches have not specifically been tested for bats. To quantify the detection probability of eDNA methods, we sampled bridges in New Jersey where bats were previously confirmed and evaluated whether eDNA analysis accurately determined bat presence. Our preliminary investigation reliably detected bats and correctly identified them to species-level. Our remaining efforts are focused on comparing detection probabilities among architectural features common to most bridges, as well as seasonal differences in detection rates. We see this project as a first step in determining whether eDNA can be a more cost-effective and non-invasive way to survey bridges for the presence of roosting bats, and ultimately aid in the conservation of threatened and endangered bat species.