Oil contamination is still a major cause of mortality in many coastal and seabird species around Europe. In a comparison with other North Sea areas, oil rates of most Belgian beached bird species are significantly higher than in northern areas such as the Shetlands and Norway, and more or less in line with oil rates at other European continental coasts. Wrecks of starved unoiled guillemots (and other species) became an almost annual event at the North Sea coasts from the first half of the ‘80s onwards, also in Belgium.Oil rates of beached bird corpses are an appropriate condition indicator of oil pollution at sea. Oil rate of most bird species/taxa in Belgium indicate a decline in oil pollution for the period 1962-99, though only Laridae, guillemot and razorbill show significant reductions. For the other taxa no significant decrease in proportion of oiled birds could be demonstrated, often due to the relatively small study area and hence insufficient number of birds collected. Assuming that a sample of at least ten complete corpses is required to calculate reliable oil rates, only the guillemot (as species) and auks (as taxon) can provide the necessary data in Belgium these days.Long-term oil pollution monitoring in Belgium should be continued with a major focus on a set of abundant bird taxa, sensitive to oil pollution and occurring in various marine habitats and the collection of additional data during the rest of the winter. Most appropriate for this set of limited bird taxa to focus on are grebes (inshore), Laridae, guillemot and razorbill (midshore) and kittiwake and fulmar (offshore).Birds dying at sea may eventually wash ashore. As such, beached bird surveys can be an important source of information concerning mortality of seabirds in the marine environment. However, there has been a lot of debate on the question how numbers of casualties on beaches relate to the actual mortality at sea and which factors affect this relationship. The temporal patterns of beached birds usually follow those of seabirds at ...