This dataset contains information on the occupancy of breeding sites in the non-breeding season, breeding timing and success, and breeding site quality for a sample of common guillemots breeding on the Isle of May, Scotland. Data is available for all attributes for the non-breeding season of 2017/18, 2018/19 and 2019/20. These data are part of the Isle of May long-term study to assess population trends of seabirds under environmental change (IMLOTS). Full details about this dataset can be found at https://doi.org/10.5285/40d28d0b-f93d-4c6c-90ef-97a26a510f81
