This dataset contains calculated breeding success rates for six seabird species from representative colonies on the Isle of May, off the East coast of Scotland. Annual breeding success has been measured as the number of chicks fledged per active nest for the Atlantic puffin (Fratercula arctica, since 1982), common guillemot (Uria aalge, since 1982), razorbill (Alca torda, since 1982), European shag (Gulosus aristotelis, since 1987), black-legged kittiwake (Rissa tridactyla, since 1987) and northern fulmar (Fulmarus glacialis, since 1987). This research was supported by NERC, through the UK Status, Change and Projections of the Environment (UK-SCAPE) programme NE/R016429/1 and the UKCEH National Capability for UK Challenges Programme NE/Y006208/1. Full details about this dataset can be found at https://doi.org/10.5285/2e0b5dac-651e-4026-8bd2-2a1da38606d6