Data on the numbers and distribution of waterbirds are required for the Strategic Environmental Assessments of Offshore Wind Farms (OWF). From February to April 2009, aerial surveys of waterbirds and seabirds were conducted off the Norfolk coast, UK, within the proposed boundary for Zone 5 of the Round 3 Development areas (Crown Estate 2008).
The Zone 5 area was divided into seven roughly equal-sized survey blocks to allow maximum coverage within each survey day. Where possible adjacent blocks were surveyed synchronously, minimizing the likelihood of double-counting due to local movements of birds between survey days.
Surveys used a standard methodology that allows collection of data suitable for distance analysis, as well as accurate plotting of locations of individual observations.
This report identifies that the area covered by the seven survey blocks supports a diverse range of waterbirds, including high numbers of Red-throated Divers. The combined area was shown to support over 3% of Britain’s wintering Red-throated Diver population (see O’Brien et al. 2008), and within this a relatively small area corresponding to two survey blocks to the east of Lowestoft, Norfolk, supports over 2%.
Caution should be used when comparing data collected during the April surveys with data from earlier dates due to migration of wintering birds away from UK waters, resulting in reduction in numbers from late March onwards, and the influx of summer breeding species such as terns.