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Seabird displacement at the Bligh Bank offshore wind farm
N. Vanermen, T. Onkelinx, W. Courtens, M. Van de walle, H. Verstraete & E.W.M. Stienen
IMCC, Glasgow 16 August 2014
Seabirds and offshore wind farms
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Barrier to migration &
local flight movements
Habitat change
Increased mortality due to collision fatalities
Seabirds and offshore wind farms
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Habitat change
Attraction? Avoidance?
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Monitoring seabird displacement
Ship-based seabird surveys according to the internationally applied ESAS methodology (Tasker,
1984)
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Monitoring displacement effects:
BACI set-upBEFORE AFTER
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control control
impact impact
Before After
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Monitoring displacement effects:
monitoring route
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Monitoring displacement effects:
data modelingStatistical challenges inherent to ‘seabirds at sea’ data
• Auto-correlation in time and space> aggregation of transect data to day totals per
control/impact area
• Overdispersion > use of a negative binomial distribution
• High proportion of zero counts > accounting for zero-inflation
ZINB modelling
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Monitoring displacement effects:
data modelingSeasonal variation modelled by a cyclic sine curve:Little gull (12 month period 2 degrees of freedom)
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Monitoring displacement effects:
data modelingSeasonal variation modelled by a cyclic sine curve:Razorbill (12 month period 2 degrees of freedom)
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Monitoring displacement effects:
data modelingSeasonal variation modelled by the sum of 2 cyclic sine curves:Black-legged kittiwake (12 + 4 month period 4 degrees of freedom)
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Monitoring displacement effects:
results Bligh Bank
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Monitoring displacement effects:
results Bligh Bank
Impact area (OWF + 0.5 km)
Impact area (OWF + 3 km)
Buffer area (0.5 - 3 km)
Coeff. P-value Coeff. P-value Coeff. P-value
Northern fulmar -16.62 0.987 -17.20 0.986 -16.49 0.987
Northern gannet -1.92 0.000*** -1.53 0.000*** -1.16 0.003**
Great skua -16.21 0.995 -16.95 0.994 -16.25 0.995
Little gull -1.15 0.270 -0.13 0.891 0.31 0.730
Common gull 1.91 0.155 1.19 0.332 -0.27 0.805
Lesser black-backed gull 1.66 0.012* 2.71 0.000*** 2.71 0.000***
Herring gull 2.25 0.001*** 0.89 0.201 0.37 0.580
Great black-backed gull 0.38 0.419 0.42 0.310 0.48 0.293
Black-legged kittiwake 0.04 0.930 0.25 0.527 0.47 0.255
Common guillemot -1.23 0.000*** -0.94 0.000*** -0.75 0.007**
Razorbill -1.01 0.031* -0.76 0.080. -0.39 0.378
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0,0
1,0
2,0
3,0
4,0
Before After
Mod
elle
d de
nsity
(n/
km²)
Northern gannet
0,0
1,5
3,0
4,5
6,0
Before After
Mod
elle
d de
nsity
(n/
km²)
Common guillemot
0,0
2,0
4,0
6,0
8,0
10,0
Before After
Mod
elle
d de
nsity
(n/
km²)
Razorbill
Control area
Impact area
Monitoring displacement effects:
results Bligh Bank
SIGNIFICANT AVOIDANCE EFFECTS-85%
-71% -64%
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Monitoring displacement effects:
results Bligh Bank
SIGNIFICANT ATTRACTION EFFECTS
0,0
1,0
2,0
3,0
4,0
5,0
Before After
Mod
elle
d de
nsity
(n/
km²)
Herring gull
0,0
1,0
2,0
3,0
4,0
5,0
Before After
Mod
elle
d de
nsity
(n/
km²)
Lesser black-backed gull
Control area
Impact area
x 9,5 x 5,3
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Observed attraction effects:ecological incentives??
Roosting possibilities (!)Food availability (?)
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to like…
…or not to like?
Observed attraction effects:
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Observed attraction effects:THANK YOU FOR YOUR ATTENTION!Any questions?
