thermal area (the Geyser Springs Group of the Gibbon Geyser Basin) has been a maternity site 

 for an unidentified species of Myotis in previous years (S Martinez personal communication) 



RESULTS 



Twenty-three sites (Figs 1-4, Table 1 ) were surveyed for bats using bat detectors (n = 21 ) 

 or mist-nets (n = 2) In addition, five bridges (one near Norris Campground outside the stud) 

 area) crossing the Gibbon River and one elevated wooded road structure crossing a thermal 

 feature were inspected for bat use, and one thermal area was checked for sign of roosting bats 

 (see Figs 2 and 4) 



Bat detector Survey Sites Bats were recorded at 17 (81°o) of 21 sites where bat detectors 

 were deployed (Table 1 ) Of the four sites with no detected activity, equipment failed at one. At 

 the sites where bats were detected, the majority ( 12 of 17) recorded low levels of activity ( 12 or 

 fewer passes) Activity at the remaining five sites ranged from 20-40 passes The vast majority 

 (> 90°o) of recorded passes occurred between 19:30-22 30 MDT at all sites 



Bats of unknown identity were detected at 1 1 sites and undifferentiated Myotis were 

 detected at 10 sites These two categories represented 151 (72 6° o) of 208 total passes recorded 

 The remaining 57 passes were identified as Western Long-eared Myotis (A/, evotis): 8 passes at 

 three sites. Big Brown Bat {Eptesicusfuscus) 1 1 passes at three sites. Silver-haired Bat 

 [Lasionycteris noctivagans) 13 passes at five sites, undifferentiated Big Browa'Silver-haired 

 bat 25 passes at 1 1 sites Four of five sites with the most activity (20 or more passes) were 

 down river from Gibbon Falls, bat activity in the Norris area was relatively widespread but at 

 low intensity Not surprisingly, greatest activity was at water sources 



Mtst-net Survey Sites Bat activity at the two sites where mist-nets were deployed was 

 low No bats were captured at the first site (*6, see Table 1 ), a small pond near a service road at 

 Gibbon Meadows However, a bat was observed flying along the road corridor nearby at crown 

 height, first at 19 45 with the last often passes at 20 35 (the nets were folded at 21 30) This 

 species was either a Big Brown or Silver-haired bat, based on size and the sound of the converted 

 vocalizations 



At the second netting site (#19. bank of Gibbon River with a small backwater of calm 

 water below Tuff Cliffs), bats were first detected at 19:52 and continued activity at very low 

 levels nearby until nets were folded (21 30) Thirteen total passes were noted in two hours of 

 netting One Little Brown Myotis (A/, lucifugus) was captured at 20 05 when it came down to 

 drink from the pocket of calm water It was a mature scrotal male (right forearm length = 38 2 

 mm. weight =8.5g) 



Bridg es Four bridges spanning the Gibbon River in the Norris-Madison Junction road 

 corridor were checked for sign of bat use The first three bridges are built with steel I-beams 

 across stone or concrete pilings, the bridge at Madison Junction is solid concrete A fifth bridge. 

 near \orns Campground, was essentially constructed like bridges B1-B3 An elevated section o\' 

 road on wooden ties and pilings at Beryl Springs was also inspected 



No bat droppings were noted under the span of the first bridge ( B 1 ) south o\~ Norris. 

 although this bridge appears to offer some suitable roosting sites Scattered bat droppings were 

 noted on stone/concrete pilings and the steel beams of bridges B2 and B3 at the upstream ends 

 Two sizes of droppings were found at bridge B3. indicating that more than one bat species has 

 roosted under this span The concrete span ( B4 ) at Madison Junction offers no roost sites for 



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