With weakly counts of a permanent beach-traject (Oostende-Nieuwpoort: 16.5 kms), five monthly counts of the whole Flemish coastline and some additional counts, 850 km of beach has been surveyed for beached birds. Another 180 birds were collected from four rehabilitation centres situated along the Flemish coast. The winter 1992-93 started with only small numbers of beached birds ( < 1 ex./km), with oil-rates of 30-45%. In the first half of January, numbers increased (particularly Waders) for the first time, due to a short period with low temperatures at the end of December. At the end of January densities increased again (up to 4 ex./km), because of increased numbers of Kittiwakes and large numbers of young, starved Guillemots. These Guillemots have very low oil-rates (11%) and are a typical example of an so-calied "auck-wreck". Backgrounds of the wreck are discussed. Until mid-March larger numbers of birds washed ashore, particularly after periods of sea-wind. Because of the abundance of Guillemots, Aucks are the best presented group, followed by Gulls, Ducks and other seabirds (Gannet, Fulmar, Great Crested Grebe Podiceps cristatus, Red-throated Diver Gavia stellata, Great Skua Stercorarius skua. Weakly counts of a permanent beach stretch give the best approach (n = 34) of the total number of species recorded (n=43). In species numbers, Ducks, Gulls and Waders are most important. In descending order, the Guillemot, Herring Gull, Kittiwake, Oystercatcher, Razorbill and Black-headed Gull are most abundant. The total number of beached birds along the Flemish coast in the period October 1992 -April 1993 is estimated at 1500-2000. This is 500 birds more than in the winter 1991-92. Based on the monthly counts, no significant differences between subtrajects could be demonstrated. Oil-rates were extremely low this winter (18%). High values in the period 1962-1975 were followed by a short decrease, and a new increase in the eighties. After peak-values in 1987, 1989 and 1990 oil-rates of seabirds and Guillemots decrease gradually unti11993. Why this low value has to be put into perspective, is discussed. Other mortality causes, found on the sampled birds, include entanglement in ropes and nets (Gannets!), stringing up of birds -deliberately or not -, swallowing of fishhooks (Gulls) and a variety of fractures and injuries, probably due to collisions with fast vessels or other objects and due to hunting. Finally the methods for beached bird surveys, as used this winter, are evaluated and same notes on the origin of beached birds on our beaches are made. |
