CAMPHUYSEN CJ (2000) Summer sightings of Manx Shearwater Puffinus puffinus in Dutch coastal waters. LIMOSA 73 (1): 7-16.

Until recently, Manx Shearwaters were known as scarce passage migrants in Dutch coastal waters, with small numbers mainly in September and October. Systematic seawatching observations since 1972 have demonstrated that Manx Shearwaters are in fact rare between November and May (but with records in each month), rather numerous in June and July along the mainland coast of Noord-Holland (up to 100 birds per day, mainly under strong onshore winds), and rather common early autumn (late August to mid-October) everywhere along the Dutch coast, particularIy with certain westerly storms. The frequent, but unexplained summer occurrences were first noticed in 1978, and were observed almost annually ever since. There are no breeding Manx Shearwaters in the North Sea except on Orkney and Shetland, and autumn passage does not commence until late August. Moulting concentrations of non-breeders are unknown at these latitudes. Ship-based surveys in the North Sea since the mid-1980s revealed rather important foraging areas of Manx Shearwaters off the British east coast. Recent sightings confirmed that these birds may wander as far out as to the Frisian Front in the southern North Sea, following rich feeding opportunities along the hydrographical front that runs parallel to the coast between the Moray Firth and Flamborough Head and along the 30m depth contour further to the east. The feeding conditions off the British coast are different each year and in some seasons feeding concentrations are immense, whereas in other years (most notably so in 1999) the productivity of the front seems rather weak and birds move further into the North Sea in search of prey. Such fluctuating feeding conditions may occasionally motivate Manx Shearwaters to move further eastward and reach the Dutch sector of the North Sea. Feeding Manx Shearwaters at the Frisian Front in June 1999 were apparently diving (pursuit plunging) rather deep for fish which most likely must have been Sprat or immature Herring. Elsewhere in the frontal area off the British coast Manx Shearwaters were seen to join feeding frenzies over near surface shoals of sandeels and to dive for mid-water shoals of Sprat and immature Herrings. Poor weather may force the shearwaters to leave the feeding areas at the Frisian Front (and become visible in Noord-Holland on their return journey back to the British coast), while in most years the shearwaters apparently mainIy stay further west. Under these conditions, as in most years, deteriorating weather does not lead to higher numbers at coastal sites in The Netherlands ####Manx Shearwater Puffinus puffinus

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