Seys, J.; Offringa, H.; Meire, P.; Van Waeyenberge, J.; Kuijken, E. (2002). Long-term changes in oil pollution off the Belgian coast: evidence from beached bird monitoring, in: Seys, J. (2001). Het gebruik van zee- en kustvogelgegevens ter ondersteuning van het beleid en beheer van de Belgische kustwateren. pp. 97-107, more
Seabirds are one of the most conspicuous faunal groups of the coastal and marine environment. For millennia humans have followed birds at sea to locate fish and mammals (Montevecchi 1993). In ancient times they formed both a source of food and a rich mythological tradition. Still, the ubiquitous calls of gulls constitute an integral and natural sound of coastal areas and mass strandings of oiled seabirds keep on attracting great public attention. Worldwide, seabird research has undergone a major evolution in terms of data collection, interpretation of the information and application in the field of management and policy (Camphuysen 1996, Tasker & Reid 1997). In this work, we will describe, analyze and interpret the substantial amount of information, collected on sea- and coastal birds in the Belgian coastal area. By processing these data we hope to contribute to a better understanding of the ecology of this faunal group and to provide tools to policy-makers, managers and researchers to use seabirds for purposes of sustainable development of the marine environment. The data can be approached in various ways. A researcher will be primarily interested in analysing and understanding the patterns of distribution, whereas policy-makers and managers are much more focused on how these data can be interpreted for the sake of conservation. Both groups should keep in mind that the methodology not only determines the efforts in the field, but also affects the final results. In general terms seabirds disperse or migrate in a coastal or marine environment (to be quantified during seawatching activities), and reside in favourable areas for longer periods (to be counted during ‘seabird at sea surveys’). In these areas they are distributed according to food availabilty, disturbance, abiotic environment or inter- and intraspecific interactions. Dedicated surveys focussing on the impact of tides or the interrelationships between various biotic and abiotic parameters (‘integral campaigns’) are useful for the understanding of the reasons behind the observed distribution patterns. When seabirds die, they may drift to the coast and eventually strand. Beached bird surveys might hence provide information on the causes and scale of mortality. By carrying out additional experiments on the drifting and sinking behaviour of bird corpses and on the disappearance and detection rates once they have beached, it is possible to better relate what is found on the beach with what has died at sea. This study mainly concentrates on seabird distribution at sea and on the mortality as observed during beached bird surveys. Breeding biological aspects as well as results of seawatching will only be dealt with briefly.