Assessing and Analyzing Bat Activity with Acoustic Monitoring

195 Pages·2017·5.1 MB·English

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Amanda M. Adams, The University of Western Ontario
Supervisor: Brock Fenton, The University of Western Ontario
A thesis submitted in partial fulfillment of the requirements for the Doctor of Philosophy degree
in Biology
© Amanda M. Adams 2013
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Adams, Amanda M., "Assessing and Analyzing Bat Activity with Acoustic Monitoring: Challenges and
Interpretations" (2013). Electronic Thesis and Dissertation Repository. 1333.
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ASSESSING AND ANALYZING BAT ACTIVITY WITH ACOUSTIC
MONITORING: CHALLENGES AND INTERPRETATIONS

(Thesis format: Integrated Article)

by

Amanda Murphy Adams

Graduate Program in Biology,
Collaborative Program in Environment & Sustainability

A thesis submitted in partial fulfillment
of the requirements for the degree of
Doctor of Philosophy

The School of Graduate and Postdoctoral Studies
The University of Western Ontario
London, Ontario, Canada

© Amanda M. Adams 2013
Abstract
Acoustic monitoring is a powerful technique for learning about the ecology of bats, but
understanding sources of variation in the data collected is important for unbiased
interpretation. The objectives of this dissertation were to investigate sources of variation
in acoustic monitoring and make recommendations for acoustic survey design and
analysis. I addressed this goal in three ways: i) variation resulting from differences in bat
detectors, ii) methods for objective identification of peak activity, and iii) the use of
stationary transects to address within-site spatial variation.
First, I compared variation of detection of echolocation calls among commonly available
bat detectors and found significant differences in distance and angle of detection.
Consequently, this source of variation should be taken into account when comparing
datasets obtained with different systems. Furthermore, choice of detector should be taken
into account when designing new studies.
Second, I investigated two statistical methods for identifying peaks in activity, percentile
thresholds and space-time scan statistic (SaTScan). Acoustic monitoring provides a
relative measure of activity levels and is rarely evaluated based on objective criteria, so
describing bat activity as “high” or “low” is useful only in context of the studies in
question. Percentile thresholds allow for peaks to be identified relative to a larger
distribution of activity levels. SaTScan identifies peaks in space and time that are
significantly higher than the background expectation of the dataset. Both methods are
valuable tools for replicable and objective identification of peak activity that can be
applied at various temporal and spatial scales.
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Third, I examine how within-site spatial variation can impact estimates of bat activity. I
used a stationary transect of bat detectors to i) assess variation in patterns of activity at
each detector, ii) test whether spatial or temporal factors were more important for
explaining variation in activity, iii) explore what sampling effort in space and time is
required for species-specific activity levels. The picture of activity differs significantly
within a site depending on detector placement so it is important to use multiple detectors
simultaneously to collect accurate estimates of activity.
Keywords

Bats, activity levels, echolocation, spatio-temporal variation, acoustic transect, passive
acoustic monitoring, bat detectors, peak activity, percentile thresholds, SaTScan.
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Co-Authorship Statement
A version of Chapter 2 was published in the Methods in Ecology and Evolution with
Meredith Jantzen, Rachel Hamilton, and Brock Fenton as co-authors. Ms. Jantzen and
Ms. Hamilton contributed to study design, data collection, and data interpretation. Dr.
Fenton provided access to equipment. All authors contributed editorial comments on the
manuscript.
A version of Chapter 3 has been submitted for publication to Acta Chiropterologica with
Liam McGuire, Lauren Hooton, and Brock Fenton as co-authors. Dr. McGuire provided
logistical support in Saskatchewan and contributed to interpretation of the data. Ms.
Hooton helped create the discriminant function analysis for species identification of
acoustic data. Dr. Fenton provided access to the acoustic equipment and funding. All
authors contributed editorial comments on the manuscript.
A version of Chapter 4 has been submitted for publication to the Journal of Applied
Ecology with Brock Fenton. Dr. Fenton provided equipment, funding, and editorial
comments on the manuscript.
A version of Chapter 5 will be submitted for publication to Ecology with Brock Fenton.
Dr. Fenton provided funding, equipment, and contributed to study design and editorial
comments on the manuscript.

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Acknowledgments
First and foremost, I would like to acknowledge my supervisor, Dr. Brock Fenton, for his
guidance and support. His limitless enthusiasm and curiosity has motivated me as an
academic. Brock’s passion for teaching, science, bats, and lifelong learning goes beyond
inspiring. Thank you for the opportunities you have opened and for never giving up on
me. Some good.
The Department of Biology has been a wonderful environment to work in as a graduate
student and I appreciate all of the faculty who took time to support me. I would like to
thank the members of my advisory committee, Drs. Nusha Keyghobadi and Jeremy
McNeil, for their recommendations, questions, and encouragement. Thanks to Ben Rubin
for always being willing to sit and talk about bats and stats with me. I am grateful for my
involvement with the Centre for Environment and Sustainability. I had the opportunity to
be part of a community of diverse and intelligent people from a wide range of disciplines.
Thank you to Dr. Dan Shrubsole who never doubted me and was always happy to talk
about anything. Also, thanks to Holly Sanderson for her support in many of my
endeavors.
I am grateful for all of my friends and colleagues at Western. Thank you to my labmates,
my family while in Canada: Dr. Signe Brinkløv, Lindsey Clairemont, Dr. Beth Clare,
Matthew Emrich, Dr. Erin Fraser, Rachel Hamilton, Colin Hayward, Lauren Hooton,
Meredith Jantzen, Louis Lazure, Dr. Liam McGuire, Dara Orbach, Leslie Reynolds, Aline
Simões, Dr. Mark Skowronski, Toby Thorne, and Nina Veselka. They have been friends,
collaborators, and valuable resources. Without their support I would not have made it
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through. Special thanks to Liam for always having the enthusiasm and encouragement to
keep me going. You are a remarkable person and never cease to amaze me. Thanks to the
Iron Chef participants for good food and something to look forward to each month. I
would also like to specially thank Erin, Johnston, and Emma for always opening their
home and hearts to me.
There are some people who are so important they have a presence in every part of your
life. Steve Duncan, Jess Hurley, Dr. Nikhil Lobo, and Dr. Katie Stammler not only helped
me maintain my sanity, but also showed me a world beyond bats. Thanks for all of the
support, stimulating conversations, laughs, and advice you have given me over the years.
Thank you to all of my friends, especially Joette Ball and Susan Morales, who continue to
support me, no matter where I am in the world.
Some of the best experiences of my life have been spent doing field work. I would trade a
day of relaxation for a night taking bats out of a net while inhaling insects and spending
time with great people. I am indebted to those I have worked with in the field: Dr. Beth
Clare, Lauren Hooton, Dr. Liam McGuire, and Juliet Nagel. I would also like to thank the
Windle family for opening their doors to me and making time spent alone collecting data
not so lonely.
I am grateful for the funding I received from Bat Conservation International, Department
of Biology, Centre for Environment and Sustainability, Graduate Teaching Assistants’
Union, and Society of Graduate Students.
Thank you to everyone I have interacted with during my time at Western. You have made
this a special part of my life. Thanks to everyone at the Grad Club; some of the best
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conversations I’ve had were while working. The encouragement everyone showed for
their resident “bat lady” made a difference. Being asked, “How are the bats,” several
times a week let me know you care and I appreciate everyone who was rooting for me to
finish.
Finally, I would like to thank all of my family. Thank you especially to my parents,
Emily, Grandma Barbara, and Laura Gomez, for their continued support and
encouragement. While everyone else thinks I am crazy for being in school for so long
their ongoing reminders of how proud they are of me has served as motivation to
persevere. I am forever grateful to my parents for instilling love and respect for nature in
me. I would not be where I am today without them, even if my dad still doesn’t
understand my obsession with bats.
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Table of Contents
Co-Authorship Statement ................................................................................................... iv
Acknowledgments ............................................................................................................... v
Table of Contents ............................................................................................................. viii
List of Tables ................................................................................................................... xiii
List of Figures ................................................................................................................... xv
List of Appendices ......................................................................................................... xviii
Chapter 1 ............................................................................................................................. 1
1 Introduction .................................................................................................................... 1
1.1 Conservation and ecological sampling ................................................................... 1
1.2 Acoustic monitoring ................................................................................................ 3
1.2.1 Species identification .................................................................................. 4
1.2.2 Environmental quality ................................................................................. 4
1.2.3 Individuals and population structure ........................................................... 5
1.2.4 Technology: advancements and limitations ................................................ 5
1.2.5 High frequency sounds ............................................................................... 6
1.3 Monitoring bats ....................................................................................................... 7
1.3.1 Acoustic monitoring today .......................................................................... 9
1.4 Variation in acoustic monitoring .......................................................................... 10
1.4.1 Variation from attenuation ........................................................................ 11
1.4.2 Variation from equipment ......................................................................... 11
1.4.3 Variation from bats ................................................................................... 12
1.5 Bat conservation .................................................................................................... 13
1.5.1 Bats as bioindicators ................................................................................. 14
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1.5.2 Current threats to bats ............................................................................... 14
1.5.3 Standardized protocols .............................................................................. 16
1.6 Dissertation structure ............................................................................................ 17
1.7 References ............................................................................................................. 19
Chapter 2 ........................................................................................................................... 35
2 Do you hear what I hear? Implications of detector selection for acoustic monitoring
of bats ........................................................................................................................... 35
2.1 Introduction ........................................................................................................... 35
2.2 Methods ................................................................................................................. 39
2.2.1 Optimizing detector recording settings ..................................................... 40
2.2.2 Synthetic call playback ............................................................................. 42
2.2.3 Recording free-flying bats ........................................................................ 44
2.3 Results ................................................................................................................... 44
2.3.1 Synthetic call playback ............................................................................. 44
2.3.2 Recording free-flying bats ........................................................................ 49
2.4 Discussion ............................................................................................................. 51
2.5 Acknowledgments ................................................................................................. 55
2.6 References ............................................................................................................. 55
Chapter 3 ........................................................................................................................... 59
3 How high is high? Using percentile thresholds to identify peak bat activity ............... 59
3.1 Introduction ........................................................................................................... 59
3.2 Methods ................................................................................................................. 61
3.2.1 Study areas ................................................................................................ 61
3.2.2 Acoustic monitoring and analysis ............................................................. 61
3.2.3 Statistical analysis ..................................................................................... 62
3.3 Results ................................................................................................................... 64
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