4.5. Gannet

  1. Monthly estimates of collisions for the worst-case for gannet are presented in Table 4.14 for both the Developer and Scoping Approaches.
  2. The estimated number of collisions was highest during July, which coincides with the second highest monthly densities of flying gannets, estimated at 1.51 birds/km2 (pooled SD ±0.23) and 1.53 birds/km2 (pooled SD ±0.17) in the Developer and Scoping Approach respectively (Table 3.3 and Table 3.4).
  3. Combining the estimated mortality across bio-seasons, shows that the estimated number of collisions is highest during the breeding season (Table 4.15).
  4. Estimated number of collisions presented in Table 4.14 and Table 4.15 were used in population modelling reported in Technical Appendix 11.6: Ornithology Population Viability Analysis.
  5. Annual collision estimates for gannets for all turbine scenarios and avoidances rates using the Developer and Scoping Approaches are presented in Table 4.16 and Table 4.17 respectively.
  6. Monthly estimates of collisions for the breeding season for gannet using an avoidance rate of 0.980 and the Band Option 2 (SNCBs, 2014) are presented for context in Table 4.18 for both the Developer and Scoping Approaches.

Table 4.14:  Monthly estimated collisions for gannet in the Proposed Development Array for the worst-case scenario (SNCBs avoidance rates, turbine 14 MW, Option 2), based on the Developer and Scoping Approaches. Estimates are presented using the mean avoidance rate (0.989) and for the mean avoidance rate ±2 standard deviations (SD) (0.002).

 

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Total

Developer Approach

- 2 SD

0.45

0.32

3.62

10.84

15.93

24.72

43.62

27.34

39.29

8.04

7.07

0.14

181.37

Estimated number of collisions

0.38

0.27

3.07*

9.17

13.48

20.92

36.91

23.13

33.24

6.80

5.99

0.12

153.48

+ 2 SD

0.31

0.22

2.51

7.50

11.03

17.11

30.20

18.93

27.20

8.04

7.07

0.14

125.58

Scoping Approach

- 2 SD

0.74

0.65

4.17

14.45

20.30

25.89

44.34

36.53

56.85

9.41

12.15

0.27

225.75

Estimated number of collisions

0.63

0.55

3.53

12.22

17.18

21.91

37.52

30.91

48.10

7.96

10.28

0.23

191.02

+ 2 SD

0.51

0.45

2.89

10.00

14.05

17.93

30.70

25.29

39.35

6.51

8.41

0.19

156.29

Table 4.15:  Estimated number of collisions for gannet by season in the Proposed Development Array for the worst-case scenario (SNCBs avoidance rates, turbine 14 MW, Option 2).

 

Bio-season

Breeding

Spring migration*

Autumn migration*

Non-breeding**

Total

Developer Approach

Estimated collisions

138.43

2.30

12.79

15.05*

153.48

Scoping Approach

Estimated collisions

169.65

3.18

18.24

21.37

191.02

*Using Furness (2015) BDMPS season definition.

**Using NatureScot (2020) non-breeding season definition.

Table 4.16:  Summary of estimated number of annual collisions for gliding gannet from the Band model Options 2 and 3 using the Developer Approach and generic flight height data, for turbine Type A (wide chord and slow rotational speed) and B (narrow chord and fast rotational speed). Avoidance rates are from SNCBs (2014) and Bowgen and Cook (2018). Estimates are rounded to the nearest whole.

 

SNCBs Guidance

Bowgen & Cook

Turbine Scenario

Avoidance rate – Basic

Avoidance rate – Extended

Option 2

Option 3

Avoidance rate – Basic

Avoidance rate – Extended

Option 2

Option 3

Type A

 

 

 

 

14MW

0.989

N/A

153

N/A

0.995

N/A

70

N/A

15MW

0.989

N/A

138

N/A

0.995

N/A

63

N/A

18MW

0.989

N/A

144

N/A

0.995

N/A

65

N/A

21MW

0.989

N/A

131

N/A

0.995

N/A

59

N/A

24MW

0.989

N/A

121

N/A

0.995

N/A

55

N/A

Type B

 

 

 

 

18MW

0.989

N/A

129

N/A

0.995

N/A

59

N/A

21MW

0.989

N/A

120

N/A

0.995

N/A

55

N/A

24MW

0.989

N/A

113

N/A

0.995

N/A

51

N/A


Table 4.17:  Summary of estimated number of annual collisions for gliding gannet from the Band model Options 2 and 3 using the Scoping Approach and generic flight height data, for turbine Type A (wide chord and slow rotational speed) and B (narrow chord and fast rotational speed). Avoidance rates are from SNCBs (2014) and Bowgen and Cook (2018). Estimates are rounded to the nearest whole.

 

SNCBs Guidance

Bowgen & Cook

Turbine Scenario

Avoidance rate – Basic

Avoidance rate – Extended

Option 2

Option 3

Avoidance rate – Basic

Avoidance rate – Extended

Option 2

Option 3

Type A

 

 

 

 

14MW

0.989

N/A

191

N/A

0.995

N/A

87

N/A

15MW

0.989

N/A

171

N/A

0.995

N/A

78

N/A

18MW

0.989

N/A

179

N/A

0.995

N/A

81

N/A

21MW

0.989

N/A

162

N/A

0.995

N/A

74

N/A

24MW

0.989

N/A

150

N/A

0.995

N/A

68

N/A

Type B

 

 

 

 

18MW

0.989

N/A

161

N/A

0.995

N/A

73

N/A

21MW

0.989

N/A

150

N/A

0.995

N/A

68

N/A

24MW

0.989

N/A

140

N/A

0.995

N/A

64

N/A

Table 4.18: Monthly estimated collisions for gliding gannet in the Proposed Development Array for the worst-case scenario (mean avoidance rate of 0.980, turbine 14 MW, Option 2) during the breeding season only, based on the Developer and Scoping Approaches and generic flight height.

 

Mar

Apr

May

Jun

Jul

Aug

Sep

Breeding season total

Developer Approach

Estimated number of collisions

5.71*

16.67

24.50

38.02

67.10

42.05

60.43

251.62

Scoping Approach

Estimated number of collisions

6.58

22.23

31.24

39.85

68.24

56.22

87.48

308.55

*March collision estimates presented are for the entire month. Gannet breeding season is estimated to start in mid-March (NatureScot, 2020), therefore, only half of the collisions for the month of March were counted in the total breeding season collision estimates.

 

4.6.        Arctic tern

4.6. Arctic tern

  1. Monthly estimates of collisions for the worst-case for Arctic tern are presented in Table 4.19 for both the Developer and Scoping Approaches.
  2. The estimated number of collisions was highest during August, when  densities of flying Artic terns were at their highest, with 1.57 birds/km2 (pooled SD ±0.35) and 2.60 birds/km2 (pooled SD ±0.33) used in the Developer and Scoping Approaches respectively (Table 3.3 and Table 3.4).
  3. Combining the estimated mortality across bio-seasons, shows that the estimated number of collisions is highest during the breeding season Table 4.20.
  4. The estimated number of collisions presented in Table 4.19 and Table 4.20 were used in population modelling reported in Technical Appendix 11.6: Ornithology Population Viability Analysis.
  5. Annual collision estimates for Arctic terns for all turbine scenarios and avoidances rates using the Developer and Scoping Approaches are presented in Table 4.21 and Table 4.22 respectively.

 

Table 4.19:  Monthly estimated collisions for Arctic tern in the Proposed Development Array for the worst-case scenario (SNCBs avoidance rates, turbine 14 MW, Option 2), based on the Developer and Scoping Approaches. Estimates are presented using the mean avoidance rate (0.980).

 

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Total

Developer Approach

Estimated number of collisions

0.00

0.00

0.00

0.03

0.21

0.12

2.14

5.57

0.03

0.00

0.00

0.00

8.10

Scoping Approach

Estimated number of collisions

0.00

0.00

0.00

0.07

0.26

0.15

4.17

9.25

0.07

0.00

0.00

0.00

13.97

 

Table 4.20:  Estimated number of collisions for Arctic tern by season in the Proposed Development Array for the worst-case scenario (SNCBs avoidance rates, turbine 14 MW, Option 2).

 

Bio-season

Breeding

Non-breeding

Total

Developer Approach

Estimated collisions

8.03

0.07

8.10

Scoping Approach

Estimated collisions

13.83*

0.13*

13.97*

*Collisions during the breeding and non-breeding seasons equate to 13.832 and 0.133 respectively (both rounded down to the nearest two decimal places numbers) and the total annual collisions equate to 13.965, rounded up to the nearest two decimal places number.


Table 4.21:  Summary of estimated number of annual collisions for Arctic tern from the Band model using the Developer Approach and generic flight height data, for turbine Type A (wide chord and slow rotational speed) and B (narrow chord and fast rotational speed). Avoidance rates are from SNCBs (2014). Estimates equal or greater than 0.5 are rounded to the nearest whole.

 

SNCBs Guidance

Turbine Scenario

Avoidance rate – Basic

Avoidance rate – Extended

Option 2

Option 3

Type A

 

 

 

 

14MW

0.98

0.98

8*

1

15MW

0.98

0.98

7

1

18MW

0.98

0.98

8*

1

21MW

0.98

0.98

7

1

24MW

0.98

0.98

7

0.45

Type B

 

 

 

 

18MW

0.98

0.98

7

1

21MW

0.98

0.98

6

1

24MW

0.98

0.98

6

1

*The estimated collisions for 14MW and 18MW turbines type A are 8.10 and 7.97 per annum, respectively.

 

Table 4.22:  Summary of estimated number of annual collisions for Arctic tern from the Band model using the Scoping Approach and generic flight height data, for turbine Type A (wide chord and slow rotational speed) and B (narrow chord and fast rotational speed). Avoidance rates are from SNCBs (2014). Estimates are rounded to the nearest whole.

 

SNCBs Guidance

Turbine Scenario

Avoidance rate – Basic

Avoidance rate – Extended

Option 2

Option 3

Type A

 

 

 

 

14MW

0.98

0.98

14*

2

15MW

0.98

0.98

12

1

18MW

0.98

0.98

14*

1

21MW

0.98

0.98

13

1

24MW

0.98

0.98

12

1

Type B

 

 

 

 

18MW

0.98

0.98

12

1

21MW

0.98

0.98

11

1

24MW

0.98

0.98

11

1

*The estimated collisions for 14MW and 18MW turbines type A are 13.97 and 13.75 per annum, respectively.


4.7.        Common tern