(A) Mean prey species by frequency, energetic proportion, and size [31] for adults used in the bio-energetics model, and (B) prey species by frequency, energetic proportion for chicks used in the bio-energetics model.

Table 2A: A division of 60 mm was chosen for 0-group sandeel and 1+ group sandeel based on fish collected from flight-netting puffins [22]. Proportions for guillemots are expressed as means across years of data collection – see Appendix S3 in File S1 for full data.Table 2B: See Appendix S1 in File S1 for more information on decisions used on raw data from all-day watches to estimate prey proportions for chicks.aBased on regurgitated samples from the Isle of May 2003 - 2007 [31].bUsing the same 0-group prey size as guillemots.cMean length value converted to energy [31].dInformation on the size of prey items deleivered to chicks are presented in Appendix S1 in File S1.