The Mute SwanCygnus olorin Britain 1983

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Abstract
A national census of the Mute Swan in Britain was carried out in spring 1983 as one contribution to a programme of monitoring the effects of lead poisoning from anglers'' weights on the population. Although full coverage of the country was attempted it was not achieved and extrapolation of the data was necessary. Comparisons with the census of 1978 show that numbers have increased nationally by about 7% to 18,750 but remain up to 8% below the level found in 1955-6. Regional variations are considerable. There have been continued declines in several lowland river systems but some sizeable increases in many other areas. An annual index of national trends in Mute Swan numbers, based on winter counts, confirms the findings of the censuses. Similar trends for other waterbird species show that the Mute Swan is an exception in not having increased substantially in the last 20-30 years.