Mean (± standard deviation) carbon and nitrogen stable isotope values of the 1st primary (P1) and the 6th rectrix (R6).

Mean (± standard deviation) carbon and nitrogen stable isotope values of the 1st primary (P1) and the 6th rectrix (R6) feathers of all the Yelkouan shearwaters breeding in Hyères Islands (France), as well as all the bycatch birds that were equally assigned to the same species by at least three of criteria presented in table 2 (ntotal = 113). All statistical significant results are marked in bold, i.e., with p-value lower that 0.0125 (Bonferroni correction). Balearic shearwaters showed significantly more enriched carbon and nitrogen isotopic values in both feathers than Yelkouan shearwaters.Mean (± standard deviation) carbon and nitrogen stable isotope values of the 1st primary (P1) and the 6th rectrix (R6).