The size of the breeding population of Manx Shearwaters Puffinus puffinus on Bardsey (Wales) in 1996

In late May and early June 1996 a whole- island survey of Manx Shearwaters was undertaken on Bardsey. All apparently occupied burrows (AOB) were counted, resulting in a total of 6927 AOBs. An additional survey of shearwaters nesting amongst gorse bushes was carried out using a call playback technique and revealed an additional 101 pairs. A comparison of the accuracy of the two censusing techniques revealed a disparity of under 10% in a selected survey area. A future monitoring program for the Manx Shearwaters on Bardsey is proposed.