Counts of marine bird species observed during three oceanographic cruises in the South-eastern part of the North Sea on board of the A962 "Mechelen" between June 1971 and January 1972. The data were digitized by VLIZ from the original report: Joiris, C. (1972). Observations ornithologiques réalisées dans le sud-est de la Mer du Nord entre juin 1971 et janvier 1972: 1. Oiseaux marins.