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Loss of tidal flats - effects on bird populations, summary
Local effects
The loss of tidal flats through enclosure has affected many coastal wetlands
in Great Britain, especially estuaries (Davidson
et al. 1991). The impact on bird populations, which rely on these areas
for food during the winter, is an important consideration for conservation of
individual species at both a local and population scale. It is generally assumed
that loss of this habitat will result in a decline in waterfowl species. Such
local studies as there are do report decline in bird numbers which can be related
to habitat loss, see for example:
The growth and expansion of Spartina
which can rapidly invade tidal mudflats, depriving several species of suitable
feeding areas, may contribute to these local impacts.
Population effects
Whilst these studies have shown a decrease in bird numbers locally, it is not
clear what impact this has on the population as a whole. Work is in progress
to predict the effects of habitat loss and change on numbers of waterbirds and
to detecting when populations as a whole have been affected (Goss-Custard
et al. 1997). Most of the existing studies which look into the effects
on the wider population are based on theoretical work (Atkinson
et al. 2001). One practical study in the Wadden Sea (Nordstrand)
was inconclusive in showing local losses resulting in wider population effects.
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Guidance: The Centre for Ecology and Hydrology, which has been
at the forefront of studying the impact of human activities on bird populations
has recently established a web site devoted to the models which it has
produced. Access this at http://www.dorset.ceh.ac.uk/shorebirds/.
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References
Atkinson, P.W., Crooks, S., Grant, A. & Rehfisch, M.M.
2001.
The Success of Creation and Restoration Schemes in Producing Intertidal Habitat for Waterbirds.
English Nature Research Report, 425
English Nature.
Davidson, N.C., Laffoley, D..d'A., Doody, J.P., Way, L.S. & Gordon, J.
1991.
Nature Conservation and Estuaries in Great Britain.
Nature Conservancy Council.
Goss-Custard, J.D., Rufino, R. & Luis, A.
1997.
Effect of Habitat Loss and Change on Waterbirds. HMSO, 144 pp.
ITE Symposium, 30
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