Description:

Spatial and seasonal distributions of selected species of seabirds in the German Bight.

Data source:

TOPAS-Windobs Datenbank + TOPAS-FTZobs Datenbank.

These are data from Environmental Impact Assessments (EIS) and monitoring studies under the permit procedures of BSH in the North Sea EEZ and research data of the FTZ.

Data collection:

Ship-based and aircraft-based transect counts.

The basis of all ship-based seabird counts is the standardized method described by Tasker et al. (1984) and Garthe et al. (2002). Following this method, seabirds within a transect strip of known length and width were recorded. Thus the number of birds per area (density) can be calculated. Seabird counts from aircrafts are described in Diederichs et al. (2002). It is also a transect based method.

Time periods: Ship: June 2000 to Aug. 2013, aircraft: March 2002 to June 2013.

Data analysis:

Based on all survey years; for each species (or species group) and each species-specific season the mean density [individuals/km²] per raster cell is calculated as "the sum of the counted seabirds divided by the sum of the survey effort inside the raster cell". Species specific correction factors were used for the calculation of the density (Garthe et al. 2007, 2009; Markones and Garthe 2012). For divers separate correction factors were calculated for each single data collection team and then combined into a weighted average.

Product description:

Vector raster with "3 km x 5 km" raster cells (EPSG 3035).

WMS: classification by mean density (5 ranges), visualization by graduated symbols.

Bibliography see: ftp://ftp.bsh.de/outgoing/gdi-bsh/public/M/M5/docs/Seebirds_density_bibliography.htm