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PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, Supplement I 
The two species of concern on island territories generally use tropical rain forest. Habitat use 
by the red fruit bat ( S. rufum ) in the U.S. Virgin Islands is not as well-understood as in Puerto Rico, 
where they are mostly known from a narrow range of elevations of a specific forest type. Species 
within the U.S. are found in different general habitats, where more specific habitats often seem to 
be associated with roost availability. Three species primarily use forests in the eastern U.S., with 
two considered abundant in southern bottomland hardwood forests where they roost in hollow trees 
(Rafinesque’s big-eared bat and the southeastern myotis). One species (the eastern small-footed 
myotis) primarily uses upland forests, often in mountainous terrain with talus-like rock features and 
caves available as roosts. Three species are characteristic of southwestern arid lowlands in the U.S.: 
the California leaf-nosed bat often uses desert washes in scrub habitats in the vicinity of old mines 
or caves; Underwood’s bonneted bat is limited to a very small area of Sonoran desert in Arizona 
near the Mexican border, where they seem to prefer roosting in cavities in saguaro cactus; and the 
nectar and fruit feeding Mexican long-tongued bat, a seasonal migrant that occupies a number of 
vegetation types (often in woodlands near riparian areas) that overlap the distribution of agaves and 
columnar cacti. A third category of habitats includes three species of bats that use a wide variety of 
habitats and elevations in the western U.S. that are within commuting distances of high cliffs and 
canyons that provide their principal known roosts (spotted bat, greater bonneted bat, and the big 
free-tailed bat). 
Western coniferous forest and woodland provides a fourth broad category of general habitat 
used by four species of myotis (western small-footed myotis, long-eared myotis, long-legged 
myotis, and fringed myotis). Use of specific habitats within these forests appears to be regionally 
or locally quite variable with specific affinities sometimes difficult to judge. The species composi¬ 
tion of bats in these western forests can include all four species, but relative abundance can vary 
radically. For example, long-eared myotis ranked as most abundant in two surveys in ponderosa 
pine forest and scrubland habitats in northeastern Oregon and south Central Washington (among 11 
species and 1,470 individuals captured), but they were much lower in relative abundance in moist 
forests farther west in those states. They ranked relatively low in abundance in surveys in Califor¬ 
nia and Nevada but were the most abundant species over the course of a 34-year study at a site in 
the San Mateo Mountains of New Mexico that entailed the capture of 1,390 individuals of 11 
species, but with fluctuations in year-to-year abundance; they were second-most abundant in a 
shorter-term study elsewhere in the same mountain range, yet were low to intermediate in abun¬ 
dance in other studies including forests and woodlands in New Mexico. Long-eared myotis were 
the most abundant or second-most abundant species in studies in ponderosa pine and pinon-juniper 
woodland in southwestern Colorado, but they were seldom captured at higher-elevation habitats in 
lodgepole pine and Douglas fir/mixed conifer forests of Colorado and were of lesser abundance on 
the eastern side of the Rocky Mountains in primarily ponderosa pine and Douglas fir/mixed conifer 
forests. The long-legged myotis, in contrast, was captured in a wide variety of western habitats and 
was usually the most abundant species in higher-elevation forests. However, long-legged myotis 
also ranked high in relative abundance in several studies across a variety of lower, drier habitats in 
a wide range of states ranging from Arizona and New Mexico north and east through the central 
rocky mountain states and western Great Plains, but not in California or in moist forests in the 
western coastal mountains of Oregon and Washington. Western small-footed myotis and fringed 
myotis (the latter species characterized in the same agility group as long-eared myotis by Norberg 
and Rayner, 1987), with few exceptions, generally ranked low to intermediate in relative abun¬ 
dance in surveys throughout their distribution. 
We placed two western species of concern in a separate category as primarily found with great¬ 
est abundance in riparian habitats (Arizona myotis and Yuma myotis), but these species also vary 
