Stable Isotope Values of Carbon and Nitrogen of Scopoli's shearwater and Yelkouan shearwater blood samples, Central Mediterranean

Stable Isotope Data used in the publication: 'Diet of two Mediterranean shearwaters revealed by DNA metabarcoding', where diet information revealed by genetic (NCBI data upload SUB15055416) and isotopic means were compared. Scopoli’s shearwaters (Calonectris diomedea) were sampled at three colonies in the Central Mediterranean, Linosa (35.865, 12.865), Malta (35.900, 14.400) and La Maddalena (41.230, 9.410), while all Yelkouan shearwater (Puffinus yelkouan) were sampled on Malta. Blood was collected during the respective species' incubation and chick-rearing stages, drawn from the tarsal vein using a syringe and 25-gauge needle in the case of Scopoli’s -, and 27-gauge needle in the case of Yelkouan shearwaters. The blood was centrifuged to separate plasma from the red blood cells (RBC) and were then stored at -18°C. Carbon and Nitrogen stable isotope valued were measured on ~0.3 mg aliquots of dried RBC. The values were measured at the LIENSs laboratory, using a Delta V Plus isotope ratio mass spectrometer equipped with a Conflo IV interface (Thermo Scientific, Bremen, Germany) and a Flash 2000 elemental analyser (Thermo Scientific, Milan, Italy). Results are reported in δ units, representing deviations from standards (Vienna Pee Dee Belemnite for δ13C and atmospheric N2 for δ15N), using the formula: δ15N or δ13C= [(Rsample/Rstandard) - 1] x 10^3; where R is 15N/14N or 13C/12C, respectively. Calibration was performed using certified reference materials: δ13C: USGS-24, IAEA-CH6, IAEA-600, USGS-61, USGS-62, USGS-63, USGS-41a; δ15N: IAEA-N2, IAEA-NO-3, IAEA-600, USGS-61, USGS-62, USGS-63, USGS-41a; with a two-point calibration method using standards USGS-61 (caffeine) and USGS-63 (caffeine). Internal laboratory standards, acetanilide (Thermo Scientific) and peptone (Sigma-Aldrich) were analysed together with the samples, yielding an analytical precision of <0.15 ‰ for δ15N and <0.10 ‰ for δ13C. The dataset containes three files where SCSH refers to Scopoli's shearwater and YESH refers to Yelkouan shearwater. In the file 'YESH_SCSH_SI_Metadata' sample information is provided and linked to the two data files from the stable isotope analysis with 'SampleID'.