Table 2. Modelling the effects of age (years), age2, sex and interactions as a function of blood δ13C and δ15N values (‰) in pre-laying snow petrels.
| Dependent variable | Independent variable | SS* | Df | F | p-value |
| a) δ13C | Age2 | 1.0 | 1,32 | 5.0 | 0.033 |
| Age | 0.9 | 1,32 | 4.5 | 0.041 | |
| Sex | 1.5 | 1,32 | 7.5 | >0.001 | |
| Age2×Age | 0.8 | 1,32 | 4.1 | 0.052 | |
| Age2×Sex | 0.7 | 1,32 | 3.7 | 0.063 | |
| Age×Sex | 0.7 | 1,32 | 3.4 | 0.074 | |
| Age2×Age×Sex | >0.1 | 1,32 | >0.1 | 0.862 | |
| b) δ15N | Age2 | >0.1 | 1,32 | >0.1 | 0.809 |
| Age | >0.1 | 1,32 | >0.1 | 0.876 | |
| Sex | 5.3 | 1,32 | 6.1 | 0.019 | |
| Age2×Age | 0.2 | 1,32 | 0.2 | 0.644 | |
| Age2×Sex | 0.6 | 1,32 | 0.7 | 0.421 | |
| Age×Sex | 0.7 | 1,32 | 0.8 | 0.369 | |
| Age2×Age×Sex | >0.1 | 1,32 | >0.1 | 0.927 |
*SS = Sum of squares.