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Gulls on Orfordness
In recent years there has been a massive increase in the populations of gulls
on Orfordness. In 1968 there were only 100 breeding pairs of Lesser black-backed
gulls (Larus fuscus) and no breeding pairs
of herring gulls (Larus argentatus). By
1999 this had increased to the 23,000 breeding pairs of Lesser black-backed
gulls and 6,500 breeding pairs of Herring gull's.
It appears that gull colonies do cause eutrophication of the shingle habitat
at Orford Ness and that the effects may be persistent. The characteristic shingle
species display increased growth and cover in response to the increased availability
of nutrients. It remains to be seen whether the gulls can co-exist with the
plant communities without extensive alteration to their composition (Evans
& Davy 2001). This issue is described in more detail in the "Guide
to the management and restoration of coastal vegetated shingle"
being prepared under contract to English Nature.
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Guidance: Detailed studies have indicated that there is no obvious
and major impact on the shingle vegetation. However this is an issue for
which there is at present no clear understanding of the likely long-term
impact on the plant communities (especially the rich lichens). Information
from other sites (Walney Island, Cumbria) suggests that in the long term
eutrophication particularly can cause the vegetation (in this case of
sand dunes) to become impoverished. Further monitoring is needed to see
if the disturbance formerly present on the site which may have restricted
nesting may need to be reintroduced.
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References
Evans, P.C. & Davy, A.J.
2001.
Effects of nesting gulls on shingle vegetation at Orfordness, Suffolk, UK.
In: Ecology & Geomorphology of Coastal Shingle, eds.Packham, J.R., Randall, R.E., Barnes, R.S.K. & Neal, A.Westbury Academic and Scientific Publishing, 197-302.
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