Stienen, E.W.M.; Courtens, W.; Van de walle, M.; Vanermen, N.; Verstraete, H. (2014). 50 jaar vogelstrandingen aan de Belgische kust. Rapporten van het Instituut voor Natuur- en Bosonderzoek, INBO.R.2014.5069823. Instituut voor Natuur- en Bosonderzoek (INBO): Brussel. 38 pp.
Part of: Rapporten van het Instituut voor Natuur- en Bosonderzoek. Instituut voor Natuur- en Bosonderzoek: Brussel. ISSN 1782-9054
This report describes the results of 50 years of beached bird surveys along the Flemish coast. The surveys are performed by volunteers and are carried on since February 1962.The surveys are primarily organized to evaluate the anthropogenic pressures on the marine ecosystem and to gain insight into the diet and mortality factors of seabirds at the Belgian part of the North Sea. The oil-rate of Common Guillemot, for example, is an indicator for the pollution of the marine environment with oil. One of the ecological indicators used by OSPAR states that a good environmental status is only reached when on average less than 10% of all stranded Guillemots is fouled with oil. Within the framework of the Marine Strategy Belgium strives for an average oil-rate of less than 20% to obtain a good environmentalstatus for its marine waters.In Belgium, the oil-rate showed a strong and significant decline during the past 50 years. During the 1960s more than 60% of the beach-washed birds were fouled with oil, while during the past few years the oil-rate was always lower than 20%. For seabirds that are most sensitive to oil pollution, like the Guillemot, the decrease is even stronger. Nowadays 15.2% of all stranded Guillemots are oiled, while during the 1960s that figure amounted to 98.8%. This means that Belgium reaches the objectives stipulated in the Marine Strategy Framework Directive (less than 20% of all stranded Guillemots should be oiled), but does not yet reach the OSPAR EcoQO-criteria (less than 10%).Also the number of birds found per km beach transect showed a strong, significant decrease over the past 50 years (from approximately 5 birds/km beach to less than 1 bird/km beach). We argue that this decline is probably fully due to a decrease in the number of oiled birds and not so much due to a possible decline in the numbers of birds present at sea.It becomes increasingly difficult to sample sufficient numbers of intact dead seabirds for our research as not only the number of strandings are decreasing but also the proportion of birdsthat is preyed upon strongly increased over the past decades. The latter is probably due to predation by foxes. As the research needs sufficient numbers of complete carcasses to obtain reliable yearly estimates of the oil-rate this urges for a more frequent beach survey.
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