Table 1. Feather isotopic signatures of seven penguin species in 2006 and 2007, and pair-wise isotopic differences between the two years.

			δ13C (‰)				δ15N (‰)
	N per year	2006	2007	2007–2006	p value	2006	2007	2007–2006	p value
Emperor penguin	17	-	−23.1±0.3	-	-	-	12.1±0.3	-	-
Adélie penguin	10	−24.2±0.4	−23.4±0.4	0.8±0.5	0.001	9.4±0.4	10.7±0.6	1.3±0.5	<0.0001
King penguin	12	−22.0±0.5	−20.7±0.6	1.3±0.6	0.0001	11.4±0.3	11.3±0.5	−0.1±0.4	0.557
Gentoo penguin	12	−19.5±0.5	−19.1±0.2	0.4±0.2	0.002	10.4±1.0	11.3±0.9	0.9±0.4	0.0001
Macaroni penguin	12	−21.4±0.3	−21.1±0.3	0.3±0.3	0.006	9.8±0.3	9.7±0.3	−0.1±0.3	0.720
Southern rockhopper penguin	12	−21.2±0.3	−21.1±0.2	0.1±0.2	0.110	9.2±0.4	8.9±0.4	−0.3±0.4	0.099
Northern rockhopper penguin	12	−18.4±0.3	−17.9±0.2	0.5±0.3	0.0002	10.3±0.3	11.3±0.4	1.0±0.4	<0.0001

Values are mean ± SD. P values correspond to paired t-tests performed between the two years. Carbon isotopic values were not corrected for Suess and increase [CO₂]_aq effects.