LOCALLY STABLE WINTERING NUMBERS IN THE OYSTERCATCHER HAEMATOPUS-OSTRALEGUS WHERE CARRYING-CAPACITY HAS NOT BEEN REACHED

Since 1976, the numbers of Oystercatchers Haematopus ostralegus winter ing on the Exe estuary have fluctuated independently of the substantia l increase over the same period in the numbers wintering in Britain as a whole, While this might imply that the carrying capacity of the Exe has been reached, closer examination suggests not, Over a sample of t he years studied, Oystercatcher numbers on the main Mussel Mytilus edu lis feeding areas increased even though the mussel bed quality remaine d unchanged, food abundance decreased and disturbance on some importan t beds increased, There was some redistribution of birds between musse l beds, apparently linked to the increased bird numbers and to a relat ive improvement in the food supply on two preferred mussel beds, The i ncrease in Oystercatcher numbers on the main feeding areas over a peri od in which the feeding conditions did not improve suggests that carry ing capacity was not reached on the mussel beds themselves and, theref ore, on the estuary as a whole.