Birds of the Bristol Channel and Severn Estuary

From the point of view of the birds which feed in these waters, it is turbidity of the water rather than salinity which represent the most significant constraint upon foraging activities. Several species have declined dramatically in numbers during the last forty years. The reasons for these changes are not known, though declining food supplies, oiling, and other forms of pollution have been suggested as possible factors. Despite the paucity of marine birds in the inner Bristol Channel, and the unsuitability of the area for feeding, it has been suggested that an overland migration route for such birds might exist between the North Sea and the Atlantic, from the Wash to the Severn. The most important concentration of marine birds in the Bristol Channel is the flock of Common Scoters, Melanitta nigra , it is probably an important moulting site for males. The largest number recorded was 25000 birds in March 1974 when passage migrants were likely to have been present-more typical wintering counts being about 6000.