scholarly journals Winter activity of boreal bats

2020 ◽  
Author(s):  
Anna S. Blomberg ◽  
Ville Vasko ◽  
Melissa B. Meierhofer ◽  
Joseph S. Johnson ◽  
Tapio Eeva ◽  
...  
Keyword(s):  
Site Selection ◽  
Barometric Pressure ◽  
Acoustic Monitoring ◽  
Passive Acoustic Monitoring ◽  
Rock Outcrops ◽  
Echolocation Calls ◽  
Bat Activity ◽  
Winter Activity ◽  
Passive Acoustic ◽  
Positive Effect

ABSTRACTNatural hibernation sites used by bats in areas that lack cave features have long remained unresolved. To investigate hibernation site selection and winter activity of boreal bats, we recorded bat calls using passive acoustic monitoring on 16 sites. These sites included four rock outcrops with crevices and cave features, three glacial erratics or boulder fields, three ancient shores, three root cellars and three control sites where we did not expect bats to be overwintering. Our results revealed echolocation calls of Eptesicus nilssonii, Plecotus auritus and Myotis sp. We recorded significantly more activity near rock outcrops and root cellars compared to other habitats. We also found that ambient temperature had a positive effect on bat activity and found evidence that P. auritus may be using low barometric pressure as a proxy for suitable foraging conditions during the winter. Our results suggest that rock outcrops may be more important to bats than previously acknowledged, highlighting the need to take these sites in account in planning of conservation measures. Furthermore, our findings underline the suitability of using acoustic monitoring in homing on hibernation sites that are not otherwise accessible.

scholarly journals Winter activity of boreal bats

2021 ◽  
Author(s):  
Anna S. Blomberg ◽  
Ville Vasko ◽  
Melissa B. Meierhofer ◽  
Joseph S. Johnson ◽  
Tapio Eeva ◽  
...  
Keyword(s):  
Site Selection ◽  
Barometric Pressure ◽  
Acoustic Monitoring ◽  
Passive Acoustic Monitoring ◽  
Rock Outcrops ◽  
Echolocation Calls ◽  
Bat Activity ◽  
Winter Activity ◽  
Passive Acoustic ◽  
Positive Effect

AbstractNatural hibernation sites used by bats in areas that lack cave features have long remained unresolved. To investigate hibernation site selection and winter activity of boreal bats, we recorded bat calls using passive acoustic monitoring at 16 sites in South-Western Finland. These sites included four rock outcrops with crevices and cave features, three glacial erratics or boulder fields, three ancient shores, three root cellars and three control sites where we did not expect bats to be overwintering. Our results revealed echolocation calls of Eptesicus nilssonii, Plecotus auritus and Myotis sp. We recorded significantly more activity near rock outcrops compared to other habitats, excluding root cellars. We also found that ambient temperature had a positive effect on bat activity and found evidence that P. auritus may be using low barometric pressure as a proxy for suitable foraging conditions during the winter. Our results suggest that rock outcrops may be more important to bats than previously acknowledged, highlighting the need to take these sites in account in planning of conservation measures. Furthermore, our findings underline the suitability of using acoustic monitoring in homing on hibernation sites that are not otherwise accessible.

How high is high? Using percentile thresholds to identify peak bat activity

2015 ◽  
Vol 93 (4) ◽  
pp. 307-313 ◽  
Author(s):  
Amanda M. Adams ◽  
Liam P. McGuire ◽  
Lauren A. Hooton ◽  
M. Brock Fenton
Keyword(s):  
Specific Activity ◽  
Activity Patterns ◽  
Acoustic Monitoring ◽  
Activity Levels ◽  
Peak Activity ◽  
Passive Acoustic Monitoring ◽  
Data Set ◽  
Bat Activity ◽  
Species Specific ◽  
Passive Acoustic

Passive acoustic monitoring is a common tool used for monitoring bat activity levels. Identifying periods and locations of peak levels provides insight into bat ecology and has important management implications. One limitation of passive acoustic monitoring is the relative nature of the data, often relying on subjective interpretation of descriptive terminology such as “higher” or “lower”. We propose the use of percentile thresholds (PTs) for objectively identifying peak activity. By compiling a reference data set, it is possible to define percentiles of the observed activity levels and these percentiles can provide objective thresholds for comparing activity levels. We used acoustic recordings from sites in Canada and calculated PTs based on the distribution of the number of calls per hour across all nights and sites for three species of bat. Given species ecologies (e.g., hibernating, migrating), we were able to use PTs to objectively identify peak activity levels on a species-specific basis. Percentile thresholds are also a replicable method of describing within-night activity by evaluating species-specific activity patterns and important times of night. Our analyses and examples represent a proof of concept. The next step is to move towards a standardized distribution to generate PTs. Creating a public repository of acoustic data sets to evaluate activity of a species in the context of its entire range would allow us to standardize terms such as “high” activity in an objective manner.

scholarly journals Noisy neighbors and reticent residents: Distinguishing resident from non-resident individuals to improve passive acoustic monitoring

2021 ◽  
pp. e01710
Author(s):  
Dana S. Reid ◽  
Connor M. Wood ◽  
Sheila A. Whitmore ◽  
William J. Berigan ◽  
John J. Keane ◽  
...  
Keyword(s):  
Acoustic Monitoring ◽  
Passive Acoustic Monitoring ◽  
Passive Acoustic

scholarly journals Environmental correlates and energetics of winter flight by bats in southern Alberta, Canada

2016 ◽  
Vol 94 (12) ◽  
pp. 829-836 ◽  
Author(s):  
B.J. Klüg-Baerwald ◽  
L.E. Gower ◽  
C.L. Lausen ◽  
R.M. Brigham
Keyword(s):  
Heat Loss ◽  
Barometric Pressure ◽  
Myotis Lucifugus ◽  
Energetic Cost ◽  
Cold Temperatures ◽  
Bat Activity ◽  
Environmental Correlates ◽  
Interspecific Differences ◽  
Winter Activity ◽  
Species Specific

Winter activity of bats is common, yet poorly understood. Other studies suggest a relationship between winter activity and ambient temperature, particularly temperature at sunset. We recorded echolocation calls to determine correlates of hourly bat activity in Dinosaur Provincial Park, Alberta, Canada. We documented bat activity in temperatures as low as −10.4 °C. We observed big brown bats (Eptesicus fuscus (Palisot de Beauvois, 1796)) flying at colder temperatures than species of Myotis bats (genus Myotis Kaup, 1829). We show that temperature and wind are important predictors of winter activity by E. fuscus and Myotis, and that Myotis may also use changes in barometric pressure to cue activity. In the absence of foraging opportunity, we suggest these environmental factors relate to heat loss and thus the energetic cost of flight. To understand the energetic consequences of bat flight in cold temperatures, we estimated energy expenditure during winter flights of E. fuscus and little brown myotis (Myotis lucifugus (Le Conte, 1831)) using species-specific parameters. We estimated that winter flight uses considerable fat stores and that flight thermogenesis could mitigate energetic costs by 20% or more. We also show that temperature-dependent interspecific differences in winter activity likely stem from differences between species in heat loss and potential for activity–thermoregulatory heat substitution.

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