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PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, Supplement I 
Rainey 1998b). Use of open areas over fields has also been noted in central Oregon (Rodhouse et 
al., 2005), and spotted bats seen foraging in Utah were described as slow and maneuverable in 
flight (Poche, 1981). 
Sizes of foraging home ranges were estimated during short-term (seven to 13 nights) radio¬ 
tracking studies in northern Arizona during 2003 and 2005 (Chambers et al., 2011). In this study 
region, they mainly foraged over Great Basin desert scrub habitats and pinon-juniper woodlands at 
distances of 11-30 kilometers from roosts. Mean home range sizes of four individuals were large, 
estimated to be 297 ± 25 (SE) square kilometers, with some individuals also using more than one 
disjunctive foraging area during the course of tracking; foraging home ranges overlapped among 
individuals and spotted bats did not appear to be territorial in this study (Chambers et al., 2011). 
Monitoring of audible calls of this species dispersing from roosts in northern Arizona revealed that 
the bats used side canyons as shared commuting flight paths to travel from lower elevation roosts 
in cliff walls, flying upwards several hundred meters in elevation. Individuals returned to day 
roosts directly and rapidly after foraging and possibly night roosting for several hours, with return 
flight speeds of three bats estimated at 30-53 kilometers per hour (Chambers et al., 2011). 
Siders et al. (1999:114) reported spotted bats as “locally common” foragers over open mead¬ 
ows in subalpine ponderosa pine and Douglas fir forests at elevations of 2,400-2,650 meters on the 
Kaibab Plateau of northern Arizona. Each night for four consecutive nights a radio-tagged lactat- 
ing female returned to the same area to forage, and would stop to night roost in an aspen grove, 
then return to the roost 38 kilometers away in lower elevation desert habitat, traveling at an esti¬ 
mated speed of 50 kilometers per hour (Rabe et al., 1998b; Siders et al., 1999). This and four other 
radio-tagged females foraged over these meadows (two also night roosted in trees bordering the 
meadows) for about three hours nightly from about 2300 h to 0200 h, making round-trip excursions 
of 77-86 kilometers from their lower elevation roosts (Rabe et al., 1998b; Siders et al., 1999). One 
adult female radio tracked in ponderosa pine forest habitats in northern New Mexico foraged as far 
as 50 kilometers round-trip from her roost (Bogan et al., 1998). 
Acoustic surveys have been used to make inferences about foraging habitat use by this species. 
These surveys have been conducted by monitoring for distinctive audible portions of their calls, as 
well as recording ultrasonic components. Storz (1995) listened for audible components at 15 sites 
in 12 locations in a variety of lower-elevation canyon bottom habitats of the Yampa and Green 
rivers at Dinosaur National Monument in northwestern Colorado and adjacent Utah. Spotted bats 
were heard at 13 of the 15 sites. Visual observations combined with listening revealed abrupt flight 
maneuvers and feeding buzzes while possibly commuting through a site. Individuals seen in more 
extended observations at foraging places over open meadows fed throughout the night and had for¬ 
aging sessions averaging 5.5 ± 2.7 (SD) minutes (n = 187), and 9.0 ± 8.8 minutes (n = 30) (Storz 
1995). Foraging bats flew in large elliptical orbits from 10 to 30 meters above ground level at the 
open meadows but also flew within eight meters of the mid and upper canopy levels of box elder 
trees in riparian zones, where they did not glean insects or fly within 0.5 meters of canopy surfaces. 
This species at Dinosaur National Monument did not concentrate foraging above rivers in 1993 and 
was not observed gleaning or hovering, but it attacked insects at a rate of about once every 2.1 min¬ 
utes, a much lower rate than seen in other species (Storz, 1995). Navo et al. (1992), however, noted 
them foraging over rivers at Dinosaur National Monument in 1990, where they foraged at heights 
of 10 meters or greater, used a variety of habitats, and were rare compared to other species based 
on acoustic recordings. Individuals observed in central Oregon foraged at heights averaging about 
20 meters above ground (ranging from about three to 50 meters), and hunted over fields, low 
upland slopes in juniper and sagebrush, and along the rims of cliffs (Rodhouse et al., 2005). The 
low frequency, long inter-pulse intervals, and low intensity calls of spotted bat echolocation have 
