Diet, timing of egg laying and breeding success data for Isle of May European shag population 1985-2015

Data on timing of breeding, breeding success and diet of the European shag, sampled from the Isle of May population. The data were collected between 1985 and 2015 by visually checking nests and collecting regurgitated diet samples. 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).Breeding phenology and success were recorded for a sample of nests every year between 1987 and 2016 (no data available for 1993 and 2003). Nests were monitored in 18 plots spread throughout the colony. Nests were checked every seven days from before laying started until after the last chick had fledged.

Sea surface temperature data were extracted for February and March in each year (from http://www.bsh.de) for an area surrounding the Isle of May that overlapped shag foraging distribution in the breeding season.

Regurgitates (from which the biomass proportions of each prey type can be estimated) were collected during the chick-rearing period (April -July) between 1985 and 2014. Collection dates showed a strong positive correlation with the timing of the shag breeding season.

Keogan, K.; Lewis, S.; Howells, R.J.; Newell, M.A.; Harris, M.P.; Burthe, S.; Phillips, R.A.; Wanless, S.; Phillimore, A.B.; Daunt, F. (2020). Diet, timing of egg laying and breeding success data for Isle of May European shag population 1985-2015. NERC Environmental Information Data Centre. https://doi.org/10.5285/6231bd5b-ee2d-4cca-a9ef-88006ffa4976