O’SHEA, CRYAN & BOGAN: UNITED STATES BAT SPECIES OF CONCERN 
55 
protection measures; most hibemacula were also threatened by human disturbance, vandalism and 
recreation. These losses could be traced to human activities in all but two of 38 cases of roosts no 
longer used (Pierson and Rainey, 1998a). Vandalism, including shooting, bashing with clubs, and 
subjecting to fire, smoke, and fireworks has been reported (Pierson et al., 1999; Oliver, 2000). Gra¬ 
ham (1966) noted that a cave housing a maternity colony in a California limestone cave had been 
permanently sealed closed. The illegal application of pesticides to destroy these bats in building 
roosts has also been documented in California (Pierson and Rainey, 1998a). Along the Colorado 
River, conversion of riparian and floodplain habitats to agricultural uses may have impacted pop¬ 
ulations of this and other species of bats through diminished quality of foraging habitat (Pierson 
and Rainey, 1998a; Brown, 2013). Remnant redwood forests may be important to these bats in 
coastal California (Fellers and Pierson, 2002). 
Humphrey and Kunz (1976) also reported this species to be very sensitive to disturbance and 
to respond more negatively to banding than other bats, showing a high proportion of band-related 
injuries, particularly in females. They concluded that they should not be banded unless important 
new capture-recapture data are needed. Handling in summer maternity roosts also caused roost 
desertion, and a decline in nursery populations that did not recover in the following year was also 
apparent; population effects due to disturbance at hibemacula were not apparent. However, this 
species shows a high rate of weight loss in winter, suggesting that disturbance during winter could 
lead to increased fat depletion and winter mortality (Humphrey and Kunz, 1976). High suscepti¬ 
bility to disturbance has also been reported for the Virginia and Ozark big-eared bats (Currie, 
2000a). 
At Lava Beds National Monument in northern California, implementation of restrictions to 
human visitation in winter and during the maternity season coincided with overall positive annual 
growth trends in counts at 52 hibemacula (Weller et al., 2014). The study by Weller et al. (2014) 
also concluded that restricting counts at hibemacula to every other year (a recommended practice 
for many cave-hibernating bats including this species; Pierson et al., 1999; Kunz, 2003; Kunz et 
al., 2009) rather than annually would be unnecessary and would reduce the sensitivity of trend 
analyses and attribution of likely causes for observed change. Greatly increasing the number of 
caves surveyed (750 caves are present in the monument) and other adjustments to sampling proto¬ 
cols are expected to provide improvements to the scale of inference for future trend estimates 
(Weller et al., 2014). 
Resource managers are often faced with difficult decisions in determining adequate levels of 
protection necessary for disturbance-sensitive species of bats. For example, in the western U.S. the 
potentially competing demands of recreational caving access, minimizing the risk of spreading the 
fungus that causes white-nose syndrome from human equipment, and the singular dependence of 
Townsend’s big-eared bats on a limited number of caves have necessitated complicated manage¬ 
ment decisions (U.S. Forest Service, 2017). Unlike areas of eastern North America where multiple 
species of bats form large hibernation colonies (more than about 100 individuals) in caves during 
winter, Townsend’s big-eared bat “.. .is the only species that can regularly be found hibernating in 
fair numbers in western caves and mines” (Barbour and Davis, 1969:165). Particular dependence 
of Townsend’s big-eared bats on caves most likely to be used for human recreation in the western 
U.S. highlights the need to consider the particular needs of each bat species when developing man¬ 
agement strategies. Using the case of Townsend’s big-eared bats in Colorado as white-nose syn¬ 
drome approaches, Neubaum et al. (2017) proposed criteria for prioritizing important bat roosts 
where management efforts could be focused. These criteria included a focus on roosts used during 
any time of year by gregarious species for reproduction, social interactions, or hibernation, as well 
as those that if negatively disturbed or lost could affect five percent or more of the management¬ 
relevant local population (Neubaum et al., 2017). 
