AUTUMN, WINTER, AND SPRING HIBERNACULA SURVEYS ALONG
PROPOSED INTERSTATE HIGHWAY CORRIDOR

In fulfillment of Tier II Environmental Impact Studies for the Federal Highway Administration (FHWA) and the Indiana Department of Transportation (IN DOT), ESI conducted autumn swarming, winter hibernation, and spring staging  surveys over a three-year period for the endangered Indiana bat (Myotis sodalis) at 37 caves in green, Monroe, and Lawrence counties, Indiana along the proposed I-69 corridor.

IN DOT and their agents, U.S. Fish & Wildlife Service (USFWS) Bloomington Field Office, Indiana Geological Survey (IGS), Indiana Karst Conservancy (IKC), and preeminent bat biologists from ESI collectively selected caves, performed field reviews and assessed bat habitat suitability. Caves were selected based on their estimated likelihood of serving as Indiana bat hibernacula and/or swarming sites, as well as proximity the proposed I-69 corridor (i.e., within a 5 miles of the corridor).

Bats were trapped at cave entrances for two nights in autumn. The same caves surveyed in autumn were entered in winter to determine the numbers and species of bats hibernating in them. Two caves of special concern were again harp trapped in spring to collect additional data on use for staging.

A total of 1761 bats were captured during harp trap surveys, including 8 Indiana bats. Winter intra-hibernaculum surveys produced 843 bats, including 30 Indiana bats. As a result of the winter surveys, a previously unknown Indiana bat hibernaculum was discovered.   Results of the surveys were incorporated into the impacts and mitigation analyses under the Endangered Species Act (ESA) and the Environmental Impact Statement (EIS) completed the National Environmental Policy Act (NEPA).  Conservation and mitigation efforts included avoidance, minimization, and compensatory commitments.

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