ABSTRACT 



An assessment of bat presence was conducted along the Norris-Madison Junction Road 

 corridor in Yellowstone National Park, Wyoming during 20-25 September 1999 Twenty-three 

 sites were monitored for bat activity, 21 sites were monitored overnight with electronic bat 

 detectors, and two sites were mist-netted for 2.0-2.5 hr after sunset. Five bridges (including one 

 just outside of the primary road corridor study area) were inspected for evidence of use by bats 

 (droppings or roosting individuals), and one additional elevated wooden road structure spanning 

 the outflow at a thermal feature was inspected for similar bat spoor One undeveloped thermal 

 area uas checked for bat spoor around boulders because the area is a known maternity site by an 

 unidentified bat species 



Bats were recorded at 17 of 21 sites monitored with bat detectors, equipment malfunction 

 occurred at one site Species tentatively identified included Western Long-eared Myotis (Myotis 

 evotis) at 3 sites. Big Brown Bat (Eptesicusfuscus) at 3 sites, and Silver-haired Bat 

 (Lasionycteris noctivagans) at 5 sites Unknown bat species were recorded at 1 1 sites, 

 unidentified Myotis at 10 sites, and indistinguishable Big Brown/Silver-haired bat at 1 1 sites. 

 The amount of bat activity (number of recorded passes) was relatively low at the majority of sites 

 where bats were detected, ranging from 1-40 passes Twelve or fewer passes were recorded at 

 1 2 of 1 7 sites. 20 or more passes were recorded at the remaining 5 sites where bats were 

 detected 



Two species of unidentified bats (one Myotis and one larger species) were observed 

 foraging at crown level among lodgepole pines at the Norris Campground (B Loop and entrance 

 area) between 19 40-21 15 MDT A few bats were observed at the two mist-netting sites, but 

 only one bat was captured, a male Little Brown Myotis (A/, lucifugus) along the Gibbon Ri\ci 

 below the Tuff Cliffs picnic area Bats observed at the second netting site (a small pond) were 

 either Big Brown or Silver-haired bats 



Three of six bridges or bridge-like structures had evidence of bat use Three of four 

 bridges with steel beams and concrete or stone pilings had concentrations of bat droppings on 

 their undersides The wooden structure at Beryl Springs and the concrete bridge spanning the 

 Gibbon River at Madison Junction are probably used little if at all as a roost site by bats. 



