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PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, Supplement I 
Assessments of potential or historic roosting sites in caves or old min es have resulted in gen¬ 
eral conclusions of major losses and often revealed an absence of any strong data usable for multi¬ 
year trend assessments. These conclusions apply to colonies of Townsend’s and Rafmesque’s big- 
eared bats, California leaf-nosed bats, and southeastern myotis. One recent study showing an 
increasing trend in counts of hibernating Townsend’s big-eared bats at hibemacula at Lava Beds 
National Monument in northern California, however, provides an example of the value of using 
count data from monitoring efforts in a strong sampling and analytical framework. Limited sam¬ 
pling indicates possible declines in eastern small-footed myotis concurrent with the advent of 
white-nose syndrome. 
One study investigated changes in abundance within an eleven-species bat community based 
on mist-netting records over a 34-year period at the same pond in the San Mateo Mountains of New 
Mexico. After statistically adjusting captures for variation in precipitation and year, an apparent 
increase in abundance was found for long-eared myotis and stability was indicated for long-legged 
myotis. Other, more short-term (four to seven years) studies have demonstrated the use of capture- 
recapture techniques for estimating population parameters for Arizona myotis and Yuma myotis. 
The Yuma myotis study also resulted in estimation of generally positive population growth rates 
using life-history based models. 
In recent years, emphasis on using presence-absence data and occupancy analysis techniques 
have been applied to development of monitoring studies of bats. These techniques have been used 
with some promise in studies of roosts of Rafmesque’s big-eared bats and southeastern myotis in 
bottomland hardwood forests of the southern U.S., and mist-netting and echolocation-detection 
studies in Washington and Oregon. In one study in the Pacific Northwest, these methods were 
shown to be feasible for long-eared myotis, fringed myotis, long-legged myotis, and Yuma myotis. 
In a second study, monitoring efforts were conducted during an eight-year period for the western 
small-footed myotis, long-eared myotis, fringed myotis, long-legged myotis, Yuma myotis, spotted 
bat, and Townsend’s big-eared bat. Only the fringed myotis showed a decline in occurrence prob¬ 
abilities over the eight-year monitoring period. 
Future efforts directed toward monitoring population dynamics and demographic changes in 
bat species of concern may benefit from clearly delineating the spatial extent of local populations 
or subpopulations. For example, the study detailing survival in a metapopulation of cave myotis in 
Oklahoma (Humphrey and Oli, 2015) showed how differences in apparent survival between sexes, 
age groups, and life stages could be discerned at spatial and temporal scales larger than single roost 
sites and years. As detailed in many of the species accounts, bats often switch between roosts. Most 
population monitoring efforts have focused on roosts. Spatially defining the boundaries of popula¬ 
tions being monitored, as well as directing monitoring efforts toward meta-roosts or multi-colony 
social groups when possible, will help expand inference that can be made about population growth 
and survival beyond the limited conclusions that can be drawn from studies focusing on one or a 
few colony sites. 
Population Genetics: Population genetic surveys have been carried out using a variety of 
methods on populations of the following species of concern: Samoan flying fox, Rafinesque’s 
big-eared bats, Townsend’s big-eared bats, spotted bats, California leaf-nosed bats, western small¬ 
footed myotis, and cave myotis. These assessments did not indicate dangerously low genetic diver¬ 
sity, although a 1976 study of allozyme variation in California leaf-nosed bats at a single min e indi¬ 
cated low heterozygosity, and diversity may be low in localized populations of Townsend’s big- 
eared bats. Additional population genetic studies of some of these species, as well as the 13 species 
not yet sampled, could benefit by assessment at more locations and with additional molecular 
analyses. 
