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The TCU • Oxford • The TCU • Oxford • NextENextErara Energy ResourcesEnergy Resources
WIND RESEARCH INITIATIVEWIND RESEARCH INITIATIVEWIND RESEARCH INITIATIVEWIND RESEARCH INITIATIVE
Estimating Bird and Bat Mortality g yat a Wind Energy Facility in
North‐Central Texas
Amanda M. Hale and Kristopher B. KarstenDepartment of Biology & The Institute for Environmental Studies
Texas Christian UniversityFort Worth, TX 76129Fort Worth, TX 76129
The TCU • Oxford • The TCU • Oxford • NextENextErara Energy ResourcesEnergy Resources
WIND RESEARCH INITIATIVEWIND RESEARCH INITIATIVEWIND RESEARCH INITIATIVEWIND RESEARCH INITIATIVEThe Institute for Environmental Studiesat Texas Christian Universityat Texas Christian University
Birds & Bats Carbon/Ecological Socio-economicBirds & Bats Carbon/Ecological Socio economic
www.wind.tcu.edu
Estimating Bird & Bat Fatality RatesEstimating Bird & Bat Fatality RatesEstimating Bird & Bat Fatality RatesEstimating Bird & Bat Fatality Rates
1. Present data from a wind energy facility in Texas
2. Example: the effect of biased scavenger removal rates onremoval rates on estimates of fatality
Wolf Ridge Wind LLCWolf Ridge Wind LLCWolf Ridge Wind, LLCWolf Ridge Wind, LLC
• 112.5 MW wind facility (75 1.5‐MW GE turbines)
Observed FatalityObserved FatalityObserved FatalityObserved Fatality
Counting Carcasses
• 2009– Line Transects (13 weeks)– Line Transects (13 weeks)
32 turbines, 6‐day search interval
Rope Method (17 weeks)– Rope Method (17 weeks)
14 turbines, 1‐day search interval
• 2010– Rope Method (15 weeks ‐ ongoing)
14 turbines, 1‐day search interval
Bird Fatalities14
12
es fo
und 2009
2010
8
10
carc
asse
6
mbe
r of c
2
4
Tota
l num
0
Week
Bird Fatalities2009 2010
35s
30
35
ther
spot
s
20
25
es &
feat N = 100 N = 21
15
20
carc
asse
10
er o
f bird
0
5
Num
be
80
90
100
2009 Bat Fatalities
60
70
80
carcasses 2010
Eastern Red Bat
30
40
50
umbe
r of c Hoary Bat
Evening Bat
0
10
20
N Tricolored Bat
Mexican Free-tailed0
5‐Apr 5‐May 5‐Jun 5‐Jul 5‐Aug 5‐Sep 5‐Oct 5‐Nov
Week
UNID Bat
• N = 458 bats2009 2010• N = 219 bats• N = 458 bats
• 30 week study period
• N = 219 bats
• 12 week study period (ongoing)
1 0
1.2
ats)
0.6
0.8
1.0
dex
(< 1
day
ba
2009
0.2
0.4
ily F
atal
ity In
d
0.0Da
Day
Bats ‐ Daily Fatality Indexy Fatality Index
0.5
0.6
ay b
ats)
20100.3
0.4
ty In
dex
(< 1
da
0
0.1
0.2
Dai
ly F
atal
it
0
Day
Estimated FatalityEstimated FatalityEstimated FatalityEstimated Fatality
Estimated Fatality =Carcasses Counted
Prop of ProportionProp. of carcasses detected
*Proportion of carcassesnot removeddetected ot e o ed
Scavenger Searcher
• Two commonly used estimators
RemovalEfficiency
Two commonly used estimators
– “Naïve estimator” Huso (2010)
– “Modified estimator”Huso (2010) Environmetrics
Bird – Estimated Fatality Rates 2009
20
y
16
18
20
erio
d
12
14
Stud
y P
8
10
es/M
W/S
4
6
Fata
litie
0
2
Raptors Non raptor birds
# F
Raptors Non-raptor birds ~3 birds/ MW/Year
Bird – Estimated Fatality Rates 2009
1 2
y
14
16
18
20
dy P
erio
d
1.0
1.2Pe
riod
0
2
4
6
8
10
12
Raptors Non-raptor birds
# Fa
talit
ies/
MW
/Stu
d
0.8
W/S
tudy
P
0 4
0.6
ties/
MW
0.2
0.4
# Fa
talit
0.0
Raptors0.13 Raptors/0.13 Raptors/ MW/Year
Bat – Estimated Fatality Rates30
y
25
Perio
d
20
/Stu
dy P
10
15
es/M
W/
5
10
Fata
litie
02009 2010
# F
~7 bats/ MW/Year
2009 2010“Modified” Estimator
Accuracy of Fatality EstimatesAccuracy of Fatality EstimatesAccuracy of Fatality EstimatesAccuracy of Fatality Estimates
• Example using mice as substitutes for bats in scavenger removal trialsg
Do Scavenger Removal Rates Differ?
0 7
0.8
0.9
1.0
maining All Bats
MiceYES
0.4
0.5
0.6
0.7
arcasses re YES
Median PersistenceBats = 5.5 days
0.1
0.2
0.3
0.4
ropo
rtion ca Bats 5.5 days
Mice = 2.5 days
(U 1889 40 P 0 0010.0
0 2 4 6 8 10 12 14 16 18 20 22
Pr
Exposure Days
(U = 1889, n1 = n2 = 40, P < 0.001
What is the impact on the estimate of fatality?
35
40
od
30
35
dy P
eri
20
25
W/S
tud
10
15
ities
/MW
5
10
# Fa
tal
0
Bats 1-day Mice 1-day Bats 3-day Mice 3-day
#
It will be biased upwards!
RecommendationsRecommendationsRecommendationsRecommendations
• Clearly define the research objectives– What level of precision is needed?
– The use of carcass substitutes can lead to biased estimates
• Need to account for seasonal variation as well as inter‐annual variation
• Experimental work is needed on efforts that could minimize impacts to birds and bats– Curtailment
– Deterrents
AcknowledgementsAcknowledgementsAcknowledgementsAcknowledgementsTh k YThank You• NextEra Energy ResourcesW lf Rid Wi d LLC T i T b id Ch i P d ff• Wolf Ridge Wind, LLC – Tommie Trowbridge, Chris Page, and staff
• Michael Slattery, Skelly Holmbeck, Lisa Thompson• Institute for Environmental Studies TCUInstitute for Environmental Studies, TCU• Department of Biology, TCU
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