Acoustic Identification of Mexican bats
PhD Veronica Zamora University of Cambridge Dr Vassilios Stathopoulos University College London
Prof. Kate Jones University College London
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Why bats?
Human ImpactEcosystem services
Climate change
Monitoring Programs
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• Must have reliable species identification
• Must be easy, cheap and be able to capture tendencies and changes in animal communities
• Bat have several monitoring challenges
• They also have other characteristics that make them ideal for acoustic monitoring
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Two main monitoring techniques
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Challenges for acoustic monitoring
1. Big acoustic diversity
Anou
ra g
eoffr
oyi
Eptesicus fuscus
Echolocating bats
Whispering bats
Three call types based on function
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Pipistrellus sp.
Eptesicus fuscus
Myotis sp.
Search calls
Social callsFeeding buzzes
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Design of different calls
Walters et al. in press Bat Ecology, Evolution & Conservation
Areas with potential acoustic monitoring
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Coverage of bat call references
Species calls similarity
3.- Acoustic Identification Tools
Real Timee.g. Pettersson D1000x, Laptop with DAQ card
Time Expansione.g. Pettersson D240x, Tranquillity Transect
Frequency division(+ Amplitude)e.g. Batbox Duet, Pettersson D230
Frequency division( - Amplitude)e.g. Anabat
Heterodinee.g. BatBox III, Magenta, Skye, many others
Russ 2012 British Bat Calls
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Detector Types
Manual
Detection and call isolation
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Antrozous pallidus real time
Antrozous pallidus compressed view
Semi-automatic software: Sonobat
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SONOBAT: 72 parameters
Supervised Learning Unsupervised LearningDi
scre
te V
aria
bles
Conti
nuou
s Var
iabl
es
ClassificationLogistic regression
RegressionTime series forecasting
ClusteringTopic Models
Mixture Models
Dimensionality reductionBlind source separation
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Acoustic Classification Techniques
Supervised Learning: Machine learning
They are trained and learn from the data
Example: sex classification
Altura Peso Tamaño Pies
1.75 78 42
1.62 53 37… … …
1.72 65 39
Sexo
Macho= 1
Hembra= 0
…
Hembra = 0
Input variables Output variable
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METODOS
Recording bats
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Recordings availability
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Theoria Metodos Resultados Parciales Retos
Nat
alus
stra
min
eus
Parameters extracted
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Random Forest: many trees
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Branches or terminal nodes, the path generated
Group of points in a d-dimensional
Parameters optimization in each
division or node
• Party package in R: conditional unbiased trees• Default Tree depth• 4 variables selected at the time to build the tree• 5000 trees• Out of bag trainning error measurement• Training 80%, testing 20%• Variables:
– Model with 71 variables– Model without amplitud– Model with 20 most important variables
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Forest Construction
PRELIMINARY RESULTS
SDM Conceptual Model Statistical Formulation Evaluation and Calibration Software
Accuracy 0.62724Kappa 0.615677AccuracyLower 0.567597AccuracyUpper 0.684149AccuracyNull 0.075269AccuracyPValue 4.06E-122
Model WITH 20 variables, 45 species and 1918 calls
Confusion Matrix by Class
Confusion Table
• Not good classification for some species
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Problems
• Unsupervised + supervised training
• Pre grouping of species?
Ideas?
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Trust funds
THANK YOU
Juan CruzadoCristina MacSwiney
Celia LopezRicardo LopezElizabeth KalkoGareth Jones
Brooke FentonMichael Barataud
Sebastien Puechmaille
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