The Influence of Temperature and Solar Radiation on Tree Roost Selection by Female Big Brown Bats (Eptesicus Fuscus) PDF Download
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Author: Kristin Jean Bondo Publisher: ISBN: Category : Bats Languages : en Pages : 180
Book Description
Although microclimate inside the roost and amount of solar radiation received have been speculated to be factors driving roost switching behavior and roost tree selection by many species of forest-dwelling bats, precisely how or if solar radiation influences tree cavity temperature at the roost and landscape levels is unknown. I evaluated whether a maternity colony of Eptesicus fuscus in Cypress Hills, SK chose to roost in the warmest trees with the highest amounts of solar radiation. I measured solar radiation and temperature simultaneously at cavities in trembling aspen trees used by bats, as well as cavities available to bats but not used. To determine if tree cavity temperature could be predicted by its location on the landscape level, I compared temperatures inside tree cavities based on aspect values generated using GIS. Mean, maximum, minimum temperature and mean rate of change inside used and available roosts did not differ significantly. Total solar radiation and solar radiation reaching the cavity entrance did not differ significantly between used and available roosts. Roost cavities did not differ in mean temperature as a function of the aspect of the terrain. Ambient temperature was strongly correlated with roost temperature between 0700 and 1600 (R2 = 0.98, t = 19.0, p = 0.000). This supports the contention that roost tree temperature inside cavities varies little and is principally determined by ambient temperature. Bats did not select or switch roost trees based on differences in temperature, but most likely select roost trees with large cavity volumes that can hold many individuals, so they can socially thermoregulate, and most likely switch roosts to avoid build up of ectoparasites, guano, and/or to facilitate knowledge and information transfer among potential roost trees.
Author: Kristin Jean Bondo Publisher: ISBN: Category : Bats Languages : en Pages : 180
Book Description
Although microclimate inside the roost and amount of solar radiation received have been speculated to be factors driving roost switching behavior and roost tree selection by many species of forest-dwelling bats, precisely how or if solar radiation influences tree cavity temperature at the roost and landscape levels is unknown. I evaluated whether a maternity colony of Eptesicus fuscus in Cypress Hills, SK chose to roost in the warmest trees with the highest amounts of solar radiation. I measured solar radiation and temperature simultaneously at cavities in trembling aspen trees used by bats, as well as cavities available to bats but not used. To determine if tree cavity temperature could be predicted by its location on the landscape level, I compared temperatures inside tree cavities based on aspect values generated using GIS. Mean, maximum, minimum temperature and mean rate of change inside used and available roosts did not differ significantly. Total solar radiation and solar radiation reaching the cavity entrance did not differ significantly between used and available roosts. Roost cavities did not differ in mean temperature as a function of the aspect of the terrain. Ambient temperature was strongly correlated with roost temperature between 0700 and 1600 (R2 = 0.98, t = 19.0, p = 0.000). This supports the contention that roost tree temperature inside cavities varies little and is principally determined by ambient temperature. Bats did not select or switch roost trees based on differences in temperature, but most likely select roost trees with large cavity volumes that can hold many individuals, so they can socially thermoregulate, and most likely switch roosts to avoid build up of ectoparasites, guano, and/or to facilitate knowledge and information transfer among potential roost trees.
Author: Jackie Dawn Metheny Publisher: ISBN: Category : Bats Languages : en Pages :
Book Description
"In Cypress Hills Interprovincial Park, Saskatchewan, Canada, tree-roosting big brown bats (Eptesicus fuscus) exhibit fission-fusion roosting behavior and are philopatric to one of three non-overlapping roosting areas. Bats switch roost trees and potentially roost-mates about every two days, and bats appear to have preferred roost-mates. To assess whether genetic relationships mediate fission-fusion behavior in tree-roosting bats, I combined genetic analyses (microsatellite loci and mitochondrial DNA) with behavioral studies. First, I determined whether female philopatry produced genetic subdivision among the roosting areas. Second, I examined roosting associations within one roosting area to determine whether roost-mate decisions were based on genetic relationships. I found that female-mediated gene flow was restricted between roosting areas while male-mediated gene flow was not. Roosting associations were not influenced by genetic relationships. Mating and dispersal behavior of E. fuscus generate group members that are generally not closely related, and bats do not preferentially roost with closely related or matrilineal females. Thus, kin selection is an unlikely explanation for preferred roost-mates, group stability, and cooperation in tree-roosting E. fuscus."--Abstract from author supplied metadata.
Author: Sandra Rancourt Publisher: ISBN: Category : Bats Languages : en Pages : 110
Book Description
Bat conservation is often hindered by a lack of geographic-specific knowledge of the bat community and the characteristics of roost sites used by reproductive females. I assessed the composition of the bat community and examined the use and characteristics of roosts selected by reproductive female big brown bats (Eptesicusfuscus) and long- eared myotis (Myotis evotis) in the Channeled Scablands of northeastern Washington. This area contains a high diversity of potential roost types (snag and tree cavities and rock and human-made structures) known to be used by both species of bats. I trapped 536 bats representing 10 species during 1996-97 using mist nets and harp traps. Radio-telemetry was used to locate 38 and 35 roosts of reproductive female big brown bats and long-eared myotis, respectively. Both species switched roosts frequently. Habitat variables were measured at three levels; the roost site, a random site near the roost, and a random site at a landscape level. Ninety-five percent (n = 36) of the big brown bat roosts were in natural tree cavities. Twenty-eight roosts were in ponderosa pine (Pinus ponderosa) and eight in aspen (Populus tremuloides). Dead tops of live pine trees were used significantly more as roosts than pine snags by big brown bats. Although there were significantly more roost trees>30 cm in diameter and taller than 12m than what was available, they were not necessarily the tallest tree in the stand. A significantly greater proportion of big brown bat roosts were found in open pine, aspen and mixed-aspen pine forests and less in grasslands and closed pine than expected. Obstruction of roost trees was not different than randomly selected trees. Big brown bat roost sites were not significantly different in forest structure than random sites. All but one of the 35 long-eared myotis roost sites were found in crevices in small basalt rock formations. Long-eared myotis roosts were in open habitats close to the edge of closed forest stands. Both species selected roosts in an area with a greater proportion of aspen and open ponderosa pine habitat. Forest restoration strategies should protect both large diameter snags but also existing dead top trees and should maintain natural population levels of biological agents that create dead tops. Restoration of historic open conditions in ponderosa pine will provide improved habitat for both big brown bats and long-eared myotis. Caution must be exercised in making generalizations about roost selection of individual bat species, given regional differences found in this and other studies.
Author: Ellen M. Whittle Publisher: ISBN: Category : Bats Languages : en Pages : 0
Book Description
Delineating habitat preferences, especially those of imperiled species, is critical to ensure that species have access to resources needed to persist. In addition to overall preferences, establishing the phenology of sensitive periods such as reproduction can be challenging for small, cryptic species such as bats. We conducted an empirical study in northeast Wyoming, USA, to characterize the habitat selection of northern long-eared bats (Myotis septentrionalis). Objectives in Chapter 1 were to (1) characterize the maternity roost-site preferences of endangered northern long-eared bats in a peripheral population occurring within a forest managed for timber harvest, and (2) determine whether roost-site preferences and switching were modulated by weather conditions. Chapter 2 objectives were (1) to assess whether maternity roost trees of northern long-eared bats are used for multiple years in northeast Wyoming; (2) to determine whether intra-seasonal occupation of maternity roosts in northeast Wyoming matches the timing of seasonal protections for northern long-eared bats; and (3) to assess the efficacy of motion-triggered game cameras for determining occupancy of maternity roosts. In our first chapter, we found that bats were more likely to select quaking aspens, snags, and trees relatively large in diameter; however, these preferences were modulated by daily weather conditions and reproductive state. Bats roosted more often in pine at warm temperatures and while lactating, and in snags when solar radiation was high and precipitation low. Bats preferred forest patches with higher canopy cover and a larger proportion of snags. In our second chapter, we documented colony occupation at maternity roosts across multiple years and outside of the protected season of June—July. We also recorded rarely documented behaviors, including pup carrying, with motion-triggered game cameras. Our findings provide guidance on habitat types that would be beneficial to conserve for northern long-eared bat populations, and more broadly, that context-dependence is an important consideration for habitat-selection studies. Peripheral populations may be critical for future recovery of declining species; however, seasonal protections against habitat disturbance may be mismatched with the phenology of populations at range edges.
Author: Edward B. Arnett Publisher: ISBN: Category : Eptesicus Languages : en Pages : 446
Book Description
I studied presence, relative abundance, and resource selection of bats in managed Douglas-fir (Pseudotsuga menziesii) forests in western Oregon from May through September, 1999-2001. Species richness was not related to elevation, density of snags, or length of edge or perennial streams in sampled landscapes. I captured bats more frequently in landscapes with moderate to high densities of snags and sex ratios were skewed toward males, especially in snag-rich landscapes at higher elevations. Elevation generally was negatively related to captures of female bats. I determined use of day roosts by female and male long-eared myotis (Myotis evotis), female long-legged myotis (Myotis volans), and female big brown bats (Eptesicus fuscus). Relative to random structures, all three species used snags that had less canopy closure, more adjacent snags, and were closer to the edge of the stand. Diameter of snags was an important variable differentiating roost and random snags used by big brown bats and long-legged myotis. I found considerable overlap in structural and contextual characteristics of snags and trees used as roosts among the three species of bats. My findings provide evidence that females of sympatric species of bats may alter their choices of roosts when co-existing in landscapes with low densities of snags. Female and male long-eared myotis primarily used stumps and down logs in landscapes with low densities of snags, while using snags more frequently in landscapes with high snag densities. I found that tree species and structural characteristics of snags, stumps, and logs used as roosts generally were similar between female and male long-eared myotis and that context variables (e.g., elevation) best differentiated use of structures between sexes. Failure to account for differences in use of roosts among species, between sexes, and among landscapes with varied conditions could lead to erroneous conclusions and ineffective or inappropriate management recommendations. Elevational gradients and densities of snags are important factors to consider when developing snag and green tree retention strategies for bats in this region. Forest management practices that retain and create large snags in landscapes currently with low densities of snags would benefit female bats, especially at lower elevations.
Author: Kristin Jean Bondo
Author: Kristin Jean Bondo
Author: Craig Kenneth Ross Willis
Author: Jody Lynn Rintoul
Author: Jackie Dawn Metheny
Author: Sandra Rancourt
Author: Ellen M. Whittle
Author: Edward B. Arnett
Author: 
Author: Daniel J. Neubaum
Author: Robert Drumm