Ardea
Official journal of the Netherlands Ornithologists' Union

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Furness R.W., Ensor K. & Hudson A.V. (1992) The use of fishery waste by gull populations around the British isles. ARDEA 80 (1): 105-113
Fishing boats in the North Sea and west of Britain may discharge as much as almost 95 000 tonnes of offal and 135 000 tonnes of whitefish discards each year, enough to feed two million scavenging seabirds. Competition for offal and discards is intense. Fulmars Fulmarus glacialis take most offal. Success rates in obtaining discards are Gannet Sula bassana > Great Skua Stercorarius skua > Great Black-backed Gull Larus marinus > Lesser Black-backed Gull L. fuscus > Herring Gull L. argentatus > Kittiwake Rissa tridactyla and Fulmar. Gannets mainly exploit discards in spring, when they cause a reduced feeding success in, and partially displace, Herring Gulls from feeding at boats. Lesser Black-backs show a greater tendency than Herring Gulls to feed at boats rather than at refuse tips. Numbers foraging at boats in the Clyde, west Scotland, in summer are large in relation to breeding numbers for Lesser and Great Black-backed Gulls. Pellets also indicate that discards are important for adult gulls of these species in summer. Discards can be an important part of Herring Gull chick diets but are rather less important for adults. Planned net-mesh changes to reduce discarding and a trend to use offal rather than discharge it may have pronounced effects on scavenging seabird populations.


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