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Kleine mantelmeeuwen Larus fuscus in de zuidelijke Noordzee in augustus en september 1995 = Lesser Black-backed Gulls in the southern North Sea in August and September 1995
Offringa, H.; Meire, P. (1995). Kleine mantelmeeuwen Larus fuscus in de zuidelijke Noordzee in augustus en september 1995 = Lesser Black-backed Gulls in the southern North Sea in August and September 1995. Oriolus 61(4): 86-90
In: Oriolus: Vlaams Tijdschrift voor Ornithologie. Koninklijke Vereniging voor Vogel- en Natuurstudie De Wielewaal/wielewaal boekhandel: Turnhout. ISSN 0774-7675, more
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Keyword
    Marine

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Abstract
    The Institute of Nature Conservation conducted seabird counts onboard of the 'R.V. Belgica' between 28 August and 8 September, intended to estimate the stock of Lesser Black-backed Gulls in the southern North Sea, In total 1182 km were surveyed in the area situated between 51° and 54°30' latitude, using the standard strip-transect method. In order to compensate for underestimation caused by congregation of gulls around fishing vessels, the density of the fishing vessels was estimated by using a line transect method. In total 9193 Lesser Black-backed Gulls were recorded, of which 612 were located 'in transect' during the strip-transect counts (353.9 km²). It was appraised that the average density of birds was 1.73/km². The overall density of vessels was approximately 0,0053/km² in a selected area of 57 000 km², with an mean flocksize of 96.6 Lesser Black-backed Gulls per ship. Summing up these two figures, it can be estimated that 100 000 - 150 000 Lesser Black-backed Gulls occurred in the southern North Sea in this period. The highest densities were found off the Belgian and Dutch coast, between Zeebrugge and Katwijk. Another patch with high density was located off NE Norfolk. The majority was associated with fishing vessels (74%, n=9193), although a group of self-feeding birds was seen off the English coast.

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