Table 3 Population median and standard deviation δ¹³C and δ¹⁵N feather values of puffins and razorbills and the population calibration-offset values and standard deviations calculated from the difference between median isoscape extracted isotope values within the population kernel density areas for each feather type and median measured feather isotope values of razorbills and puffins in winters 2007/8 and 2014/15

From: Sympatric Atlantic puffins and razorbills show contrasting responses to adverse marine conditions during winter foraging within the North Sea