Gardline Environmental Ltd conducted monthly boat based ornithological surveys for the Dogger Bank Offshore Wind Farm project on behalf of Forewind Ltd from 2010 to 2012.The data are made available in Microsoft Access database format. The database was developed by the British Trust for Ornithology (BTO) and replaced the Excel spreadsheets historically used in recording ESAS (European seabirds at sea) to prevent erroneous data entry.The survey area of the Dogger Bank Round 3 offshore wind farm zone was covered by 41 parallel transect lines. These lines were divided into 21 primary lines and 20 secondary lines. Depending on the geographical focus of the project at the time, specific parts of the zone were surveyed as priority. Dedicated seabird surveyors untook the surveys using the Camphuysen method as recommended by COWRIE. The survey vessel Jan 2010 – Sept 2010 was the Sea Profiler. This was replaced in October 2010 by the Vigilant. During the zone appraisal in 2010, primary transects across the zone were 8km apart, these were offset with secondary transects 4 km between each primary line. For 2010 all primary lines were completed first. If time allowed during the month, the secondary transects would also be undertaken. By using relatively wide spacing for the transect lines, all of the zone would be surveyed even during the winter months (shorter day light hours and more weather downtime being major constraints). At the beginning of 2011,Tranche A was identified. For the next 12 months, transects (primary and secondary) within Tranche A were prioritised over rest of zone. In July 2011 Tranche B was identified and equal priority with Tranche A. Priority for Tranche A finishes with December 2011 survey. The 2012 survey months were identified by BTO after comparision with the boat and aerial bird data. The 4 months where surveys were carried out were Jan, March/April, May and June.