A random encounter model for estimating bat abundances · PDF fileA random encounter model for estimating bat abundances ... Species Eptesicus serotinus ... A random encounter model

A random encounter model forestimating bat abundances

Tim C.D. Lucas@timcdlucas

CoMPLEX, GEEUniversity College London

22-03-2013 #BritBats

A digression to begin with...

How many bats are there?

A random encounter modelAlso known as a ‘gas model’

A random encounter modelAlso known as a ‘gas model’

Bats aren’t circlesThey’re segments

γ1

θγ2

ψ

Some assumptions

Discrete inside/outside of call ‘segment’

Probably more probabilistic than this

Some assumptions

Straight line movement

Number of detections is Poisson

Are detections Poisson?

100% 50% 5% 2%

Bat

spe

rKM

2

01

23

45

6

Percent of Ukraine P. kuhlii sample size

Estimate and theoretical CIBootstrap mean and CI

SimulationsWith Liz Moorcroft

Compare model sensitivity:

- Species parameters- Movement models- Population density

Required parameters

Species Eptesicus serotinus

Call intensity 128dBHalf amplitude angle 36◦

Flight speed 13.2ms−1

Call frequency 26.94kHz

Bat detector

SensitivityAngle of operation

Required parameters

Species Eptesicus serotinus

Call intensity 128dBHalf amplitude angle 36◦

Flight speed 13.2ms−1

Call frequency 26.94kHz

Bat detector

SensitivityAngle of operation

Required parameters

Species Eptesicus serotinus

Call intensity 128dBHalf amplitude angle 36◦

Flight speed 13.2ms−1

Call frequency 26.94kHz

Bat detector

SensitivityAngle of operation

Thanks for listening@timcdlucas

γ1

θγ2

ψ

D =capture

zq

q =r

π

(2

∫ π/2

(π−θa)/2sin

θa2sin γ1

√va2 + vd2 − 2vavd cos

ψ

2dγ1

+

∫ θa+θd/2

θa

sin γ2

√va2 + vd2 − 2vavd cos

ψ

2dγ2

)