4.7. Common tern
- Monthly estimates of collisions for the worst-case for common tern are presented in Table 4.23 for both the Developer and Scoping Approaches.
- The estimated number of collisions was highest during August, when the mean and max monthly densities of flying common terns were at their highest, with 0.45 birds/km2 (pooled SD ±0.13) and 0.69 birds/km2 (pooled SD ±0.18) respectively (Table 3.3 and Table 3.4).
- Combining the estimated monthly mortality across bio-seasons shows that the estimated number of collisions is highest during the breeding season (Table 4.24).
- The estimated number of collisions presented in Table 4.23 and Table 4.24 were used in population modelling reported in Technical Appendix 11.6: Ornithology Population Viability Analysis.
- Annual collision estimates for common terns for all turbine scenarios and avoidance rates using the Developer and Scoping Approaches are presented in Table 4.25 and Table 4.26 respectively.
Table 4.23: Monthly estimated collisions for common 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 | 0.10 | 0.06 | 0.00 | 0.75 | 4.85 | 0.30 | 0.00 | 0.00 | 0.00 | 6.05 |
Scoping Approach | |||||||||||||
Estimated number of collisions | 0.00 | 0.00 | 0.00 | 0.21 | 0.11 | 0.00 | 0.81 | 7.43 | 0.59 | 0.00 | 0.00 | 0.00 | 9.15 |
Table 4.24: Estimated number of collisions for common 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 | 5.80 | 0.25 | 6.05 |
Scoping Approach | Estimated collisions | 8.65 | 0.50 | 9.15 |
Table 4.25: Summary of estimated number of annual collisions for common tern 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). 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 | 6* | 1 |
15MW | 0.98 | 0.98 | 5 | 1 |
18MW | 0.98 | 0.98 | 6* | 1 |
21MW | 0.98 | 0.98 | 5 | 1 |
24MW | 0.98 | 0.98 | 5 | 0.46 |
Type B |
|
|
|
|
18MW | 0.98 | 0.98 | 5 | 1 |
21MW | 0.98 | 0.98 | 5 | 1 |
24MW | 0.98 | 0.98 | 5 | 1 |
Table 4.26: Summary of estimated number of annual collisions for common tern 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). 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 | 9* | 1 |
15MW | 0.98 | 0.98 | 8 | 1 |
18MW | 0.98 | 0.98 | 9* | 1 |
21MW | 0.98 | 0.98 | 8 | 1 |
24MW | 0.98 | 0.98 | 8 | 1 |
Type B |
|
|
|
|
18MW | 0.98 | 0.98 | 8 | 1 |
21MW | 0.98 | 0.98 | 7 | 1 |
24MW | 0.98 | 0.98 | 7 | 1 |
*The estimated collisions for 14MW and 18MW turbines type A are 9.15 and 8.90 per annum, respectively.
4.8. Little gull
4.8. Little gull
- Monthly estimates of collisions for the worst-case for little gull are presented in Table 4.27 for both the Developer and the Scoping Approaches.
- The estimated number of collisions was highest during August, when the densities of flying little gulls were at their highest, with 0.07 birds/km2 (pooled SD ± 0.04) and 0.12 birds/km2 (pooled SD ±0.05) respectively (Table 3.3 and Table 3.4).
- Combining the estimated mortality across bio-seasons, shows that the estimated number of collisions is highest during the non-breeding season. This is mainly explained as little gulls do not breed in the UK and their presence and, therefore collision risk, is mainly confined to the non-breeding season (Table 4.28).
- The estimated number of collisions presented in Table 4.27 and Table 4.28 were used in population modelling reported in Technical Appendix 11.6: Ornithology Population Viability Analysis.
- Annual collision estimates for little gulls for all turbine scenarios and avoidance rates using the Developer and Scoping Approaches are presented in Table 4.29 and Table 4.30 respectively.
Table 4.27: Monthly estimated collisions for little gull 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 | 0.19 | 0.00 | 0.00 | 0.00 | 0.00 | 0.17 | 2.01 | 0.00 | 0.00 | 0.00 | 0.08 | 2.45 |
Scoping Approach | |||||||||||||
Estimated number of collisions | 0.00 | 0.38 | 0.00 | 0.00 | 0.00 | 0.00 | 0.35 | 3.71 | 0.00 | 0.00 | 0.00 | 0.16 | 4.60 |
Table 4.28: Estimated number of collisions for little gull by season in the Proposed Development Array for the worst-case scenario (SNCBs avoidance rates, turbine 14 MW, Option 2).
| Bio-season | Summer months | Non-breeding | Total |
|---|---|---|---|---|
Developer Approach | Estimated collisions | 0.17 | 2.28 | 2.45 |
Scoping Approach | Estimated collisions | 0.35 | 4.25 | 4.60 |
Table 4.29: Summary of estimated number of annual collisions for little gull for the five wind turbine generator sizes 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). 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 | 2* | 0.40 | |
15MW | 0.98 | 0.98 | 2* | 0.37 | |
18MW | 0.98 | 0.98 | 2* | 0.31 | |
21MW | 0.98 | 0.98 | 2* | 0.26 | |
24MW | 0.98 | 0.98 | 2* | 0.22 | |
Type B |
|
|
|
| |
18MW | 0.98 | 0.98 | 2** | 0.32 | |
21MW | 0.98 | 0.98 | 2** | 0.28 | |
24MW | 0.98 | 0.98 | 2** | 0.25 | |
*The estimated collisions for 14 MW; 15 MW; 18 MW; 21 MW and 24 MW turbines type A are 2.45; 2.04; 2.38; 2.19 and 2.05 per annum, respectively.
**The estimated collisions for 18 MW; 21 MW and 24 MW turbines type B are 1.98; 1.86 and 1.77 per annum, respectively.
Table 4.30: Summary of estimated number of annual collisions for little gull for the five wind turbine generator sizes 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). 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 | 5 | 1 | |
15MW | 0.98 | 0.98 | 4 | 1 | |
18MW | 0.98 | 0.98 | 4 | 1 | |
21MW | 0.98 | 0.98 | 4 | 0.48 | |
24MW | 0.98 | 0.98 | 4 | 0.41 | |
Type B |
|
|
|
| |
18MW | 0.98 | 0.98 | 2* | 0.32 | |
21MW | 0.98 | 0.98 | 2* | 0.28 | |
24MW | 0.98 | 0.98 | 2* | 0.20 | |
*The estimated collisions for 18MW; 21MW and 24MW turbines type B are 1.98; 1.86 and 1.77 per annum, respectively.