Provenance & quality
Data have been collected by Centre for Ecology & Hydrology (CEH) staff on the May National Nature Reserve, Scotland (56°11′N, 02°33′W) using standardised methods since 1987, and this work has continued to the present as part of the Isle of May Long-term Study (IMLOTS; https://www.ceh.ac.uk/our-science/projects/isle-may-long-term-study).
As part of this long-term study, data on year-round guillemot activity was collected as part of a biologging project part-funded by the Royal Society for the Prevention of Cruelty to Animals. Biologging data were collected using global location sensing (GLS) time depth recorder (TDR) devices during 2005 –2006. From these data we derived guillemot activity budgets (hours spent diving, flying, at the colony, active on water and inactive on water), sea surface temperature values (SST; recorded by the bird-borne loggers), energy expenditure, location fixes and the proportion of dive activity that occurred during day, twilight and night. Year-round colony attendance was also recorded using time-lapse photography. The full methodology is available in the Supporting Information document attached to this record.