4.3. Herring gull
- Monthly estimates of collisions for the worst-case scenario for herring gull are presented in Table 4.6 for both the Developer and Scoping Approaches.
- The estimated number of collisions was highest during July, when monthly densities of flying herring gulls were at their highest, with 0.32 birds/km2 (pooled SD ± 0.10) and 0.48 birds/km2 (pooled SD ±0.12) used in the Developer and Scoping Approach 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 breeding season (Table 4.7).
- The estimated number of collisions presented in Table 4.6 and Table 4.7 were used in population modelling reported in Technical Appendix 11.6: Ornithology Population Viability Analysis.
- Annual collision estimates for herring gulls for all turbine scenarios, and avoidance rates using the Developer and Scoping Approaches are presented in Table 4.8 and Table 4.9 respectively.
Table 4.6: Monthly estimated collisions for herring gull 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 (0.995) and for the mean avoidance rate ±2 standard deviations (SD) (0.001).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Developer Approach | |||||||||||||
- 2 SD | 1.08 | 0.00 | 0.29 | 0.00 | 0.00 | 10.05 | 19.77 | 1.51 | 0.00 | 0.00 | 1.32 | 1.84 | 35.84 |
Estimated number of collisions | 0.90 | 0.00 | 0.24 | 0.00 | 0.00 | 8.37 | 16.47 | 1.26 | 0.00 | 0.00 | 1.10 | 1.53 | 29.87 |
+ 2 SD | 0.72 | 0.00 | 0.20 | 0.00 | 0.00 | 6.70 | 13.18 | 1.00 | 0.00 | 0.00 | 0.88 | 1.22 | 23.89 |
Scoping Approach | |||||||||||||
- 2 SD | 2.15 | 0.00 | 0.59 | 0.00 | 0.00 | 20.09 | 30.12 | 1.51 | 0.00 | 0.00 | 2.63 | 3.15 | 60.54 |
Estimated number of collisions | 1.80 | 0.00 | 0.49 | 0.00 | 0.00 | 16.74 | 25.10 | 1.51 | 0.00 | 0.00 | 2.19 | 2.62 | 50.45 |
+ 2 SD | 1.44 | 0.00 | 0.39 | 0.00 | 0.00 | 13.39 | 20.08 | 1.21 | 0.00 | 0.00 | 1.75 | 2.10 | 40.36 |
Table 4.7: Estimated number of collisions for herring gull 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 | 26.10 | 3.77 | 29.87 |
Scoping Approach | Estimated collisions | 43.35 | 7.10 | 50.45 |
Table 4.8: Summary of estimated number of annual collisions for herring gull 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 | 0.995 | 0.99 | 30 | 18 | 0.995 | 0.993 | 30 | 13 |
15MW | 0.995 | 0.99 | 26 | 17 | 0.995 | 0.993 | 26 | 12 |
18MW | 0.995 | 0.99 | 28 | 14 | 0.995 | 0.993 | 28 | 10 |
21MW | 0.995 | 0.99 | 26 | 11 | 0.995 | 0.993 | 26 | 8 |
24MW | 0.995 | 0.99 | 24 | 10 | 0.995 | 0.993 | 24 | 7 |
Type B |
|
|
|
| ||||
18MW | 0.995 | 0.99 | 25 | 15 | 0.995 | 0.993 | 25 | 10 |
21MW | 0.995 | 0.99 | 23 | 13 | 0.995 | 0.993 | 23 | 8 |
24MW | 0.995 | 0.99 | 21 | 11 | 0.995 | 0.993 | 21 | 8 |
Table 4.9: Summary of estimated number of annual collisions for herring gull 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 | 0.995 | 0.99 | 50 | 31 | 0.995 | 0.993 | 50 | 21 |
15MW | 0.995 | 0.99 | 44 | 29 | 0.995 | 0.993 | 44 | 20 |
18MW | 0.995 | 0.99 | 47 | 24 | 0.995 | 0.993 | 47 | 16 |
21MW | 0.995 | 0.99 | 43 | 19 | 0.995 | 0.993 | 43 | 14 |
24MW | 0.995 | 0.99 | 40 | 17 | 0.995 | 0.993 | 40 | 12 |
Type B |
|
|
|
| ||||
18MW | 0.995 | 0.99 | 42 | 25 | 0.995 | 0.993 | 42 | 17 |
21MW | 0.995 | 0.99 | 39 | 21 | 0.995 | 0.993 | 39 | 15 |
24MW | 0.995 | 0.99 | 36 | 19 | 0.995 | 0.993 | 36 | 13 |