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1

Another quantitative measure of bat species activity and sampling intensity considerations for the design of ultrasonic monitoring studies

100%
Broders H. G.
Acta Chiropterologica
|
2003
|
tom 05
|
nr 2
To date, much of the research that has used ultrasonic detectors as a tool to address questions on the spatial and temporal distribution of bat species activity have been limited by the lack of a reliable and quantifiable unit of activity, and a poor understanding of sampling intensity required to accurately assess site-specific activity levels. Here it is demonstrated that file size (i.e., bytes) of Anabat-recorded echolocation sequences of the little brown bat (Myotis lucifugus) was highly correlated with the number of calls, and was easily determined, and therefore represents a reliable and quantifiable unit of echolocation activity. Additionally, it is shown that accurate quantification of a site-specific magnitude of M. lucifugus activity may not be possible, even with a sampling intensity of up to 20 nights. As a result, ultrasonic monitoring studies must be designed to minimize the effects of the high variability in bat species activity at a site among nights.
2

Identification and characterization of swarming sites used by bats in Nova Scotia, Canada

63%
Randal J., Broders H. G.
Acta Chiropterologica
|
2014
|
tom 16
|
nr 1
For bats that are year-round residents of temperate areas, underground openings such as caves and abandoned mines are critical resources in winter as hibernacula, and in autumn for swarming behaviours (mating, socialization, etc.). Like many parts of the world, Nova Scotia, Canada, has many underground openings that have not been surveyed for bats. The feature(s) that affect the suitability of these sites for hibernation or swarming is not known. As such, it is not possible to predict which ones are used by local bats (Myotis lucifugus, Myotis septentrionalis and Perimyotis subflavus). Because it was not safe to enter the sites to conduct hibernation counts, our goal was to relate bat activity at the entrance of underground openings during swarming to quantifiable external metrics and to pre-existing data on internal site characteristics. Specifically, our objectives were to 1) identify abandoned mines and caves that are used by bats for swarming and 2) quantitatively characterize factors which best differentiate between underground openings that are used for swarming, and those that are not. We assumed that sites used by bats for swarming were likely also used for hibernation. Acoustic and/or trapping surveys were conducted at 17 abandoned mines and eight caves in Nova Scotia, five of which were previously known to be hibernacula. Results suggest that at least 12 of the 25 sites were swarming sites (including seven newly identified sites). Logistic regression analysis of nine a priori selected models indicated that internal chamber length was the best predictor of swarming activity. Two external variables, degree of shelter at entrance and total length of rivers in landscape, were also important predictors. These variables have the potential to be used as indicators to identify swarming sites at other sites in eastern North America. The swarming sites identified in Nova Scotia should be targeted for monitoring in light of the devastating impacts that white-nose syndrome is having on North American bats.
3

Stable isotopes reveal that little brown bats have a broader dietary niche than northern long-eared bats

45%
Broders H. G., Farrow L. J., Hearn R. N., Lawrence L. M., Forbes G. J.
Acta Chiropterologica
|
2014
|
tom 16
|
nr 2
Stable isotope analysis (SIA) was used to quantify intra- and interspecific variation in the δ13C and δ15N values in plagiopatagium tissue of little brown (Myotis lucifugus) and northern long-eared (M. septentrionalis) bats in several regions of the Canadian Maritimes where they occur in sympatry. There was large intraspecific variation in the δ13C of M. lucifugus, with the range exceeding 30‰, whereas the range of δ13C values observed in M. septentrionalis was less than 7‰. Similarly, the standard ellipse area of M. lucifugus was larger than that of M. septentrionalis at all sites and together, these data support the contention that M. lucifugus has broader dietary niche breadth than M. septentrionalis. Some M. lucifugus from Fundy National Park, New Brunswick exhibited very low δ13C values, suggesting an energy input from an unknown source, possibly with carbon assimilated from biogenic methane. High δ13C values for M. lucifugus from Brier Island, Nova Scotia are consistent with a diet that is at least partially derived from marine sources. Finally, δ15N values for both species from Prince Edward Island were high relative to New Brunswick or Nova Scotia, suggesting inputs of anthropogenically-derived nitrogen from a more agriculturally-intensive landscape.
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