Abstract
This report gives a second, and preliminary, summary of results of seabird counts conducted in and around the OWEZ wind farm, after this offshore wind farm became operational in the Dutch sector of the North Sea. After a series of eight “Before” or T-0 surveys (2002-2004) and a first set of six “After” or T-1 surveys were conducted (2007-2008), a second series of six T-1 surveys was carried out (2008-2009). All surveys followed the same (ten) pre-determined transect lines running from E-W through a survey area of about 20x20 nm, with the wind farm situated centrally.
In this second interim report, a first comparison is made between the T-0 and the two T-1 surveys. Raw data are plotted for all surveys, showing firstly all birds seen along the survey lines, and secondly only those birds that could be used for density estimations. When sufficient data were collected for a given seabird species and month, Generalised Additive Mixed Models (GAMM) or Generalised Additive Models (GAM) models were used to explore the relative contributions of location, expressed as distance to shore and latitude and the presence of the OWEZ wind farm and the adjacent Princess Amalia Wind Farm, to the distribution patterns found.