This series contains an addendum to the to the Ornithological Assessment reported in the Environmental Statement (OWPL 2002) for the proposed Inner Dowsing offshore wind farm. The report provides the findings of the thirteenth, fourteenth, fifteenth, sixteenth and seventeenth boat surveys and the results of the overall distance band analyses. Estimated totals for all species recorded in transect extrapolated to the whole wind farm site, and corrected for underestimation of birds seen due to distance, are also provided. Revised conclusions based upon these are also presented. The addendum figures are also provided.