Table 2 Bulk and compound-specific stable isotopic analyses of inter-specific differences of seabirds during the breeding season (based on red blood cell samples)

Gentoo penguin

5

− 17.1 ± 0.4^b

14.7 ± 0.1^b

3.7 ± 0.2^a,b

27.7 ± 1.5^b

7.5 ± 0.2^b

Magellanic penguin

5

− 17.5 ± 0.4^a,b

14.3 ± 0.6^a,b

3.9 ± 0.1^a

26.2 ± 0.3^b

6.9 ± 0.8^b

Rockhopper penguin

5

− 18.1 ± 0.6^a

13.6 ± 0.2^a

3.4 ± 0.1^c

23.3 ± 0.6^a

7.2 ± 0.9^b

Thin-billed prion

5

− 19.8 ± 0.4^c

12.1 ± 0.9^c

3.5 ± 0.1^b,c

22.1 ± 1.1^a

5.4 ± 0.4^a

ANOVA

F_16,3 = 22.2, P < 0.001

F_16,3 = 31.0, P < 0.001

F_16,3 = 12.9, P < 0.001

F_16,3 = 19.4, P < 0.001

F_16,3 = 12.0, P < 0.001