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BATS
OVERVIEW
The staff at Big Oaks NWR conducted mist net surveys for Indiana bats on the refuge in 1998 & 1999 to document the use of use of the refuge by this federal and state-endangered species. The annual report covering these efforts can be found here (pdf).
Additional mist net surveys were conducted by the Bloomington Ecological Services Office from 1995 to 1997 on the former Jefferson Proving Ground (now Big Oaks NWR). These survey efforts showed the importance of the habitats on Jefferson Proving Ground for endangered species and furthered the cause for the former Jefferson Proving Ground becoming a national wildlife refuge.
METHODS
Mist-nets were placed in travel lanes of bats in likely foraging locations usually over water. Nets were placed to completely cover the riparian corridor from water level to canopy height and from bank to bank. Nets were typically opened (i.e., set for capture) at dusk and checked every 20 minutes to remove captured bats until approximately 0100 hr. The capture of bats is restricted to nights with no wind or slight breezes and no precipitation. This is due to the increased possibility of detection of the mist net by bats when wet or blown by the wind and the possibility of injury to bats once caught.
DATA
The sex, age, reproductive status, and weight of all bats captured was recorded. Reproductive status of females were classified as pregnant or as lactating. Radio transmitters (<0.80g) were attached with non-toxic skin bond adhesive only to adult females and juvenile Indiana bats using standard region wide procedures. Radio-tagged bats were monitored daily until the transmitter falls off or became non-functioning. Indiana bats were held as briefly as possible (< 45 min; unless injured) to expedite measurements and radio-marking.
