Wild Bird Control and Monitoring Areas, stretching about 20km including Chesil Beach, the popular tourist location where the swannery is situated, the Portland Bill headland and Weymouth were set up when disease was confirmed last Thursday.

The boundaries, which stretch beyond the minimum 3km and 10km requirements, took into account local bird reserves and the presence of wild bird populations.

Bird keepers inside the Control and Monitoring Areas are required to house their birds or otherwise isolate them from contact with wild birds. Bird movements are restricted and bird gatherings are banned, although Defra was this week considering issuing licences for some movements.