Surveys for Northern Long-Eared Bat Use of Nebraska Bridge Structures

In December 2013, the U.S. Fish and Wildlife Service (USFWS) proposed listing the northern long-eared bat (Myotis septentrionalis) (NLEB) under the Endangered Species Act (ESA) (87 Stat. 884, as amended; 16 U.S.C. 1531 et seq.) as federally endangered. The State of Nebraska is located within the known range of this species. The final listing decision is expected in April 2015. At this time, very little is known about this species habitat use in Nebraska. During the winter, NLEBs predominately hibernate in caves and abandoned mine portals. During the summer, NLEBs typically roost singly or in colonies in cavities, underneath bark, crevices, or hollows in both live and dead trees and/or snags. Males and non-reproductive females may also roost in cooler places such as caves and mines. Occasionally, NLEBs have been documented roosting in man-made structures, such as buildings, barns, bridges, and culverts during the summer, particularly when suitable tree roosting sites are unavailable. They forage for insects over water, forest clearings, and under tree canopies in upland and lowland woodlots and tree-lined corridors. Because little is currently known about this species use of bridges and culverts, USFWS is concerned that Nebraska Department of Roads (NDOR) actions to repair or replace bridge and culvert structures may harm NLEB. Experts have hypothesized that the bridge and culvert structures in Nebraska are too dry and cold to contain the necessary moisture and temperature regimen desired by Nebraska bat species for roosting. Once the species is listed, NDOR will be obligated under ESA to avoid “take” of the species. More information is needed to determine if this species of bat is using NDOR bridge and culvert structures and if additional measures would be needed during construction of these structures to avoid “take” of the species. The objective of this study is to identify if bats are using NDOR bridge and culvert structures and if they are, what types of structures are being utilized for roosting. The results of the study would help project biologists and planners better understand what types of impacts, if any, bridge and culvert construction may have on a soon-to-be protected species and help drive decisions on how to best avoid impacts to the NLEB to remain in compliance with ESA.