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?