4.2. Kittiwake

  1. Monthly estimates of annual collisions for the worst-case for kittiwake are presented in Table 4.2 for both the Developer and Scoping Approaches. The total estimated annual number of collisions of kittiwake were 685 and 986 for the Developer and Scoping Approaches respectively.
  2. Results from using site-specific flight heights for kittiwakes from rangefinder and visual observer data and modelled using option 1 of Band (2012) were considerably lower (Annex B, Table 2 and Table 3). Based on rangefinder data, the mean estimated annual number of collisions for kittiwake using the Developer and Scoping Approaches were 56 and 81 birds respectively. Using the visual observer collected data, the annual mean increased to 225 and 324 kittiwakes for the Developer and Scoping Approaches respectively (Table 3).   
  3. The estimated number of collisions was highest during May, which coincides with the second and third peaks in mean and max monthly densities of flying kittiwakes, with 4.91 birds/km2 (pooled SD ±0.86) and 6.73 birds/km2 (pooled SD ±1.06) respectively (Table 3.3 and Table 3.4).
  4. Combining the estimated number of collisions across bio-seasons, shows it to be highest during the breeding season (Table 4.3). However, the numbers of estimated collisions remain relatively high year-round throughout the non-breeding season.
  5. The estimated number of collisions presented in Table 4.2 and Table 4.3 were used in population modelling reported in Technical Appendix 11.6: Ornithology Population Viability Analysis.
  6. Annual collision estimates for kittiwakes for all turbine scenarios and avoidance rates using the Developer and Scoping Approaches are presented in Table 4.4 and Table 4.5 respectively.

 

Table 4.2:  Monthly estimated annual collisions for kittiwake in the Proposed Development Array for the worst-case design 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

23.02

11.15

79.83

137.61

144.98

133.04

57.52

98.77

54.67

20.29

38.63

9.88

809.38

Estimated number of collisions

19.48

9.43

67.55

116.45

122.68

112.58

48.67

83.57

46.26

17.17

32.69

8.36

684.90

+ 2 SD

15.94

7.72

55.27

95.28

100.38

92.11

39.82

68.38

37.85

14.05

26.74

6.84

560.40

Scoping Approach

- 2 SD

23.65

12.29

90.40

196.51

198.93

243.30

63.84

124.68

91.93

31.35

72.45

15.97

1165.30

Estimated number of collisions

20.01

10.40

76.49

166.29

168.33

205.88

54.02

105.51

77.79

26.53

61.31

13.52

986.07

+ 2 SD

16.37

8.51

62.59

136.06

137.73

168.46

44.20

86.33

63.65

21.71

50.16

11.06

806.82

Table 4.3:  Estimated number of collisions for kittiwake 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

425.73

154.69

104.48

259.17

684.90

Scoping Approach

Estimated collisions

616.88

190.05

179.15

369.19

986.07

*Using Furness (2015) BDMPS season definition.

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


Table 4.4:  Summary of estimated number of annual collisions for kittiwake 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) 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

685

N/A

0.99

0.98

623

216

15MW

0.989

N/A

573

N/A

0.99

0.98

521

203

18MW

0.989

N/A

653

N/A

0.99

0.98

594

166

21MW

0.989

N/A

600

N/A

0.99

0.98

545

136

24MW

0.989

N/A

559

N/A

0.99

0.98

508

116

Type B

 

 

 

 

18MW

0.989

N/A

548

N/A

0.99

0.98

498

174

21MW

0.989

N/A

513

N/A

0.99

0.98

466

149

24MW

0.989

N/A

484

N/A

0.99

0.98

440

133

Table 4.5:  Summary of estimated number of annual collisions for kittiwake 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) 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

986

N/A

0.99

0.98

896

311

15MW

0.989

N/A

826

N/A

0.99

0.98

751

293

18MW

0.989

N/A

940

N/A

0.99

0.98

855

238

21MW

0.989

N/A

864

N/A

0.99

0.98

785

196

24MW

0.989

N/A

804

N/A

0.99

0.98

731

168

Type B

 

 

 

 

18MW

0.989

N/A

789

N/A

0.99

0.98

717

250

21MW

0.989

N/A

738

N/A

0.99

0.98

671

215

24MW

0.989

N/A

697

N/A

0.99

0.98

633

192

 

4.3.        Herring gull