Population Consequences of Displacement from Proposed Offshore Wind Energy Developments for Seabirds Breeding at Scottish Spas Final Report
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Population Consequences of Displacement from Proposed Offshore Wind Energy Developments for Seabirds Breeding at Scottish SPAs Final Report Population consequences of displacement from proposed offshore wind energy developments for seabirds breeding at Scottish SPAs (CR/2012/03) Final report to Marine Scotland Science Searle, K., Mobbs, D., Butler, A., Bogdanova, M., Freeman, S., Wanless, S. & Daunt, F. May 2014 Contents 1 Project scope ....................................................................................................................... 9 2 Methodology ..................................................................................................................... 10 2.1 Prey and bird density maps ................................................................................................. 10 2.1.1 Data on bird distributions ............................................................................................ 11 2.1.2 Estimation of bird densities ......................................................................................... 12 2.1.3 Estimation of prey densities ........................................................................................ 15 2.2 The foraging model .............................................................................................................. 15 2.2.1 Selection of foraging location ...................................................................................... 15 2.2.2 Intake rate and intra-specific interference competition ............................................. 18 2.2.3 Cost model ................................................................................................................... 19 2.2.4 Behavioural modes for adults and chicks and subsequent decisions .......................... 20 2.2.5 Adult body mass change .............................................................................................. 21 2.2.6 Chick growth ................................................................................................................ 21 2.2.7 Time steps and number of flights per day ................................................................... 21 2.2.8 Sources and values for parameters in the foraging model. ......................................... 22 2.3 Effect of wind farms ............................................................................................................ 25 2.3.1 Impact scenarios .......................................................................................................... 25 2.3.2 Spatial model for displacement and barrier effects .................................................... 25 2.4 Translating impacts on adult mass into impacts on adult survival ...................................... 26 2.5 Exploratory model runs ....................................................................................................... 28 2.6 Final model runs .................................................................................................................. 30 2.6.1 Revisions to the full model .......................................................................................... 30 2.6.2 Use of a “fast model” ................................................................................................... 30 2.6.3 Adjustment .................................................................................................................. 32 2.6.4 Sensitivity analysis ....................................................................................................... 34 3 Results ............................................................................................................................... 37 3.1 Destinations of birds ............................................................................................................ 37 3.2 Impact of wind farms on adult survival and breeding success ............................................ 39 3.3 Sensitivity analysis ............................................................................................................... 43 3.3.1 Baseline sensitivity ....................................................................................................... 43 3.3.2 Sensitivity of wind farm effects ................................................................................... 44 4 Discussion .......................................................................................................................... 47 4.1 Summary of results .............................................................................................................. 47 2 | P a g e CR/2012/03: final report May 2014 4.2 Uncertainty........................................................................................................................... 49 4.2.1 Sources of uncertainty.................................................................................................. 49 4.2.2 Sampling uncertainty .................................................................................................... 49 4.2.3 Parametric uncertainty ................................................................................................. 50 4.2.4 Structural uncertainty .................................................................................................. 50 4.2.5 Reducing uncertainty: further work ............................................................................. 52 4.3 Conclusions .......................................................................................................................... 52 5 Acknowledgements ........................................................................................................... 53 6 References ......................................................................................................................... 53 Appendix A. Habitat association modelling ................................................................................. 57 A.1. Environmental data .............................................................................................................. 57 A.2. Habitat association model ................................................................................................... 58 A.3. Assessing model performance ............................................................................................. 60 A.4. Results .................................................................................................................................. 60 A.4.1. Habitat suitability ......................................................................................................... 60 A.4.2. Predicted bird density .................................................................................................. 62 A.5. Interpretation ....................................................................................................................... 65 Appendix B. Example prey density maps used in the foraging model ........................................ 67 Appendix C. Detailed foraging model structure .......................................................................... 71 Appendix D. Source literature for model parameters. ................................................................ 77 Appendix E. Quantification of uncertainty within exploratory runs ........................................... 81 E.1. Quantifying uncertainty ....................................................................................................... 81 E.2. Presenting uncertainty ......................................................................................................... 82 E.3. Sources of uncertainty ......................................................................................................... 83 E.4. Reducing uncertainty ........................................................................................................... 83 Appendix F. Full model results from exploratory runs with 1000 birds ...................................... 85 F.1. Prey availability in good, moderate and poor years ............................................................ 85 F.2. Black-legged kittiwake Rissa tridactyla ................................................................................ 87 F.2.1. The effects of wind farms and prey availability ........................................................... 87 F.2.2. The effects of buffer width ........................................................................................... 94 F.2.3. The effects of percentage of birds displaced ............................................................... 97 F.3. Common guillemot Uria aalge ........................................................................................... 100 F.3.1. The effects of wind farms and prey availability ......................................................... 100 F.3.2. The effects of buffer width ......................................................................................... 107 3 | P a g e F.3.3. The effects of percentage of birds displaced ............................................................. 110 F.4. Razorbill Alca torda............................................................................................................ 113 F.4.1. The effects of wind farms and prey availability ......................................................... 113 F.4.2. The effects of buffer width .......................................................................................