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`Impact of mute swans on agricultural and fishing interests: Wylye and Upper Avon Valleys, Wiltshire` - VC0105

In recent years, a significant number of complaints have been made relating to the damage caused to agricultural and riverine enterprises by Mute Swans. Agricultural damage may include direct grazing losses of improved grassland and silage contamination by excessive deposits of droppings. In addition, damage to riverine ecosystems may be caused by swan grazing of water crowfoot (Ranunculus spp.), which deprives trout of both cover and insect food and makes conditions unsuitable for spawning. This study will aim to evaluate the impact of swan grazing on the Rivers Avon and Wylye, together with their surrounding fields, and to investigate possible management options to minimise the environmental impact of the birds. A summary report will be compiled on the ADAS research of 1991/92 into swan feeding activity on the River Wylye, with particular reference to Ranunculus spp. A fortnightly count will be conducted of swan numbers on the Rivers Wylye and Avon, aerial photographs of the 2 rivers will be taken and fortnightly observations of alleged grazing of Ranunculus spp. will be carried out at critical locations. Swan activity on the rivers and neighbouring fields will be recorded in detail from dawn until dusk, allowing comparison with similar data recorded by ADAS in 1991/2. Data obtained on swan breeding success and immigration into the area under research will be compared with that recorded by the local swan study group and an attempt will be made to analyse any illegal controls carried out. Information will be obtained on flow rates, water quality and other factors which could have contributed to the poor growth rate of Ranunculus spp. in recent years and the possibility of encouraging growth of plants less palatable to swans will be discussed. Full liaison will take place both within ADAS and with outside bodies to compare relevant damage claims being made elsewhere, a full literature search will be conducted and a consultation document will be produced, suggesting potential management options as alternatives to licensed culling, translocation and egg pricking.
Time-Scale and Cost
From: 1995

To: 1996

Cost: £43,000
Contractor / Funded Organisations
Fields of Study
Wildlife Management