White River National Forest bat survey and monitoring 2016-2018

Prepared for: USDA Forest Service, White River National ForestIncludes bibliographical references

RECORDS OF THE EASTERN RED BAT ON THE NORTHERN FRONT RANGE OF COLORADO

Although common in deciduous forest throughout the Midwest and east-central states, the eastern red bat (Lasiurus borealis) is rare in Colorado (Armstrong et al. 1994, Fitzgerald et al. 1994). However, this species has the potential to extend its range because belts of eastern deciduous forest habitat have expanded across western prairies and reached the Front Range of Colorado over the last 100 years (Knopf 1986). The eastern red bat ranges from Canada southward across the United States to northeastern New Mexico with most records occurring east of the Continental Divide (Hall 1981, Shump and Shump 1982, Cryan 2003). The historical range of the eastern red bat in Colorado extends along the riparian forest habitat of the South Platte and Arkansas rivers of eastern Colorado as far west as Boulder and Pueblo counties, respectively. Previous records of this species in Colorado are either individual animals caught incidentally or those submitted by the public to the Colorado Division of Public Health and Environment that lacked accurate location information (Armstrong et al. 1994). Everette et al. (2001) tentatively identified the presence of red bats on the outskirts of Denver, Colorado as recently as 2 and 7 July 1997, based on four echolocation calls recorded with Anabat detectors. Despite extensive mist netting, no red bats were captured. No new records have been reported for this species in Colorado since that time

RECORDS OF THE EASTERN RED BAT ON THE NORTHERN FRONT RANGE OF COLORADO

Although common in deciduous forest throughout the Midwest and east-central states, the eastern red bat (Lasiurus borealis) is rare in Colorado (Armstrong et al. 1994, Fitzgerald et al. 1994). However, this species has the potential to extend its range because belts of eastern deciduous forest habitat have expanded across western prairies and reached the Front Range of Colorado over the last 100 years (Knopf 1986). The eastern red bat ranges from Canada southward across the United States to northeastern New Mexico with most records occurring east of the Continental Divide (Hall 1981, Shump and Shump 1982, Cryan 2003). The historical range of the eastern red bat in Colorado extends along the riparian forest habitat of the South Platte and Arkansas rivers of eastern Colorado as far west as Boulder and Pueblo counties, respectively. Previous records of this species in Colorado are either individual animals caught incidentally or those submitted by the public to the Colorado Division of Public Health and Environment that lacked accurate location information (Armstrong et al. 1994). Everette et al. (2001) tentatively identified the presence of red bats on the outskirts of Denver, Colorado as recently as 2 and 7 July 1997, based on four echolocation calls recorded with Anabat detectors. Despite extensive mist netting, no red bats were captured. No new records have been reported for this species in Colorado since that time

Unsuspected retreats: autumn transitional roosts and presumed winter hibernacula of little brown myotis in Colorado

Documentation of autumn and winter roosts of many species of hibernating bats are lacking from western North America. However, recent evidence suggests that rather than using caves and mines, many individuals and some species of bats may roost in inconspicuous rock crevices at these times of year. I investigated autumn use of rock crevices and other roosts by the little brown myotis (Myotis lucifugus) in the Rocky Mountains of western Colorado through radiotelemetry (n = 38). Objectives were to determine the types and characteristics of roosts, describe patterns of movements to these roosts from summer colonies, and contrast findings with results of surveys of bats in cave and abandoned mines in Colorado during autumn and winter. Forty-four autumn transitional roosts and presumed hibernacula were located in buildings, trees, and rock crevices. Bats used short-distance movements changing in elevation to autumn transitional roosts and presumed hibernacula rather than major latitudinal migrations. Roost type and distance from capture site to roosts had the highest variable importance at the landscape scale. Microclimate comparisons showed that buildings provided warmer minimum average temperatures, which may benefit juvenile bats early in the transition season. Tree roost temperatures during autumn would allow bats to conserve energy by using daily torpor and passive rewarming to assist with afternoon arousals. Rock crevice roosts in talus were found to be suitable for hibernation by exhibiting the coolest average temperatures and maintaining the highest relative humidity levels. Autumn access and spring egress to high-elevation talus sites used by these bats were not obstructed by winter snow pack. These rock crevices also provided temperature and humidity levels that would support the persistence and growth of Pseudogymnoascus destructans (Pd), the causal agent of white-nose syndrome. However, bats in this study appeared to roost alone, which could inhibit the bat-to-bat spread of Pd. Surveys of caves and mines w

Factors Influencing Movement Probabilities of Big Brown Bats (\u3ci\u3eEptesicus fuscus\u3c/i\u3e) in Buildings

We investigated movements of female big brown bats (Eptesicus fuscus) roosting in maternity colonies in buildings in Fort Collins, Colorado (USA), during the summers of 2002, 2003, and 2005. This behavior can be of public health concern where bats that may carry diseases (e.g., rabies) move among buildings occupied by people. We used passive integrated transponders (PIT tags) to mark individual bats and hoop PIT readers at emergence points to passively monitor the use of building roosts by marked adult females on a daily basis during the lactation phase of reproduction. Multi-strata models were used to examine movements among roosts in relation to ambient temperatures and ectoparasite loads. Our results suggest that high ambient temperatures influence movements. Numbers of mites (Steatonyssus occidentalis) did not appear to influence movements of female bats among building roosts. In an urban landscape, periods with unusually hot conditions are accompanied by shifting of bats to different buildings or segments of buildings, and this behavior may increase the potential for contact with people in settings where, in comparison to their more regularly used buildings, the bats may be more likely to be of public concern as nuisances or health risks

Guidelines for Defining Biologically Important Bat Roosts: A Case Study from Colorado

Conservation of roosts is regularly recommended as a strategy to decrease the risk of threats to local bat populations (e.g., white-nose syndrome). Determining whether a roost site plays a meaningful role in maintaining a local bat population can be difficult given the variability found in roost structure type, and use by season, duration, and sex. Here we provide land managers and biologists with guidelines to aid in the decision process for determining which roosts are biologically important in maintaining healthy bat populations at a local scale. We define methods for determining biologically important roost sites and provide a case study of their use on bat roosts in Colorado. To be considered biologically important, we suggest that a roost meet two primary criteria: 1) it is considered a hibernaculum, maternity roost, transient roost, colonial bachelor roost, or fall swarming site used by bat species that are gregarious roosters, hibernators, or are known to swarm, and 2) if the site is disturbed or lost, it could affect 5% or more of the local population of the species, as defined by the investigator. Additive measures to further evaluate the importance of the roost and assign higher conservation value include: 1) a roost used by a special status species and 2) large aggregations of bats where an estimated 20% or more of the local population is roosting or swarming at the site. We also provide definitions for the seasonality of roost types, examples of several real-life scenarios where management decisions have been made for roosts, and a worksheet that helps guide users through the process

A review of bat hibernacula across the western United States: Implications for white-nose syndrome surveillance and management

Efforts to conserve bats in the western United States have long been impeded by a lack of information on their winter whereabouts, particularly bats in the genus Myotis. The recent arrival of white-nose syndrome in western North America has increased the urgency to characterize winter roost habitats in this region. We compiled 4,549 winter bat survey records from 2,888 unique structures across 11 western states. Myotis bats were reported from 18.5% of structures with 95% of aggregations composed of ≤10 individuals. Only 11 structures contained ≥100 Myotis individuals and 6 contained ≥500 individuals. Townsend’s big-eared bat (Corynorhinus townsendii) were reported from 38% of structures, with 72% of aggregations composed of ≤10 individuals. Aggregations of ≥100 Townsend’s big-eared bats were observed at 41 different caves or mines across 9 states. We used zero-inflated negative binomial regression to explore biogeographic patterns of winter roost counts. Myotis counts were greater in caves than mines, in more recent years, and in more easterly longitudes, northerly latitudes, higher elevations, and in areas with higher surface temperatures and lower precipitation. Townsend’s big-eared bat counts were greater in caves, during more recent years, and in more westerly longitudes. Karst topography was associated with higher Townsend’s big-eared bat counts but did not appear to influence Myotis counts. We found stable or slightly-increasing trends over time in counts for both Myotis and Townsend’s big-eared bats from 82 hibernacula surveyed ≥5 winters since 1990. Highly-dispersed winter roosting of Myotis in the western USA complicates efforts to monitor population trends and impacts of disease. However, our results reveal opportunities to monitor winter population status of Townsend’s big-eared bats across this region