Beached Bird Surveys, Dec 1990 – Feb 1991

During the 1990/1991 season of Beached Bird Surveys (BBS), two different periods should be recognized; November 1990 through January 1991, and February-March 1991. The first period can be characterized by mild weather, westerly winds and mass mortality of (oiled) auks, the latter by a relatively short spell of very cold weather and easterly winds in February and rather quiet, mild weather in March. The species composition of stranded birds in these two periods was quite different; as shown in figure 1. Auks predominated in early winter (Nov-Jan 62.5%, n= 3,102), while waders were most numerous in Feb-Mar (46.9%, n= 2,293). Massive numbers of severely oiled Guillemots crashed on the mainland coast in November (see Sula 4(4)). Autopsy showed that most of these birds were mature, actively engaged in pre-nuptial moult and in pretty good condition, while their main prey appeared to be Sprat Sprattus sprattus. In December, considerably lower numbers washed ashore, with many slightly oil contaminated, but still with many adult birds. Razorbills were rather scarce. An increase in numbers of Guillemots on the tideline was witnessed in January. No less than 69.2% (n= 968) of the reported corpses were auks. An influx of Little Auks along the Dutch coast (see seawatching results) was also recorded in the January BBS: nearly 40 corpses reported, mainly in Noord-Holland. Since large sections of the Wadden Sea islands remained unsurveyed, the total number of Little Auks on the coast will probably have been in the range of at least 50-100 individuals. Puffins were found, but in very small numbers. Razorbills remained relatively scarce (R:G as 1:11 in January).