Departure of Manx Shearwater Puffinus puffinus fledglings from Bardsey, Gwynedd, Wales, 1998 to 2013

Abstract

Very little has been published about how soon Manx Shearwater Puffinus puffinus fledglings leave the area around the natal colony, clearly because of the difficulty of re-catching them after they are first ringed and of knowing whether or not recaptured birds had flown (Perrins et al. 1973; Perrins 2014). Fledglings are thought to depart southwards promptly after they finally leave the natal burrow because the food supply near the colony is deteriorating as the breeding season draws to a close, as suggested by the earlier departure of the adults and the lighter weights of later fledglings, and also as evidenced by the paucity of recoveries immediately after fledging, gale-wrecked birds apart (Brooke 1990). Catching Manx Shearwaters on Bardsey, Gwynedd, Wales at lighthouse attractions within the perimeter of the lighthouse complex, and re-catching them there and on the ground elsewhere on the island, showed that not all fledglings left the area immediately, with a few remaining for up to five/six days. The data published here relate to the numbers initially attracted to the lighthouse and later re-attracted or otherwise caught again in late August and September, between 1998 and 2013.