NORTHEASTERN NATURALIST 2006 13(1):25–28 Efficacy of the Mist-net Protocol for Indiana Bats: A Video Analysis KATHLEEN A. MACCARTHY 1,2 , TIMOTHY C. CARTER 1 , BRADLEY J. STEFFEN 1 , AND GEORGE A. FELDHAMER 1,* Abstract - We mist-netted bats to test the efficacy of the US Fish and Wildlife Service Indiana Bat Protocol (IBP), which recommends monitoring nets every 20 min. We continuously videotaped mist nets while monitoring and removing bats every 20 min. We recorded 157 bats on video that approached within 10 m of the mist net. Thirty-six bats (23.1%) avoided the net, 79 (50.0%) were caught and collected, and 42 (26.9%) were caught but escaped before we returned to check the net. We recommend that researchers check mist nets at intervals ≤ 10 minutes to potentially increase capture rates by ≥ 25%. Introduction Flying bats are difficult to capture because of their ability to avoid mist nets by detecting objects as thin as 0.06 mm in diameter (Kunz et al. 1996, Waldien and Hayes 1999). However, mist-netting is still the most common method of capture and has been used to study most bat species (Jones et al. 1996, Kunz and Kurta 1988), including the endangered Myotis sodalis Miller and Allen (Indiana bat) (Gardner et al. 1989). Mist-netting guidelines (MNG) of the US Fish and Wildlife Service (1999) Indiana Bat Protocol (IBP) recommend using a 2-ply, 50-denier nylon net with approximately 38-mm mesh and monitoring nets every 20 min to efficiently capture Indiana bats for accurate survey information. Our objective was to assess the MNG by quanti- fying the number of bats that escaped from nets during 20-min intervals. Methods We sampled sites within Shawnee National Forest in southern Illinois. Sites were dominated by bottomland hardwood forest, with closed canopy in close proximity to water. Dominant forest overstory species included Quercus velutina Lam. (black oak), Q. palustris Muench. (pin oak), Q. alba L. (white oak), and Carya spp. (hickories). Forested wetlands were charac- terized by an overstory of Fraxinus spp. (ash), Platanus occidentalis L. (sycamore), and Liquidambar styraciflua L. (sweetgum), with few woody understory species. 1 Department of Zoology, Southern Illinois University, Carbondale, IL 62901-6501. 2 Current address - United States Department of Agriculture, Animal and Plant Inspection Service, Wildlife Services, National Wildlife Research Center, 4101 LaPorte Avenue, Fort Collins, CO 80521. * Corresponding author - feldhamer@zoology.siu.edu.