This dataset contains information on the breeding outcome, breeding site occupancy, and breeding site quality for a sample of common guillemots breeding on the Isle of May, Scotland. Data is available for all attributes from 1981-2018. These data are part of the Isle of May long-term study to assess population trends of seabirds under environmental change (IMLOTS https://www.ceh.ac.uk/our-science/projects/isle-may-long-term-study). Full details about this dataset can be found at https://doi.org/10.5285/33b42f0a-12a5-47fe-aaaf-25f4ee5e13a5
