. 2011 Feb 2;6(2):e16484. doi: 10.1371/journal.pone.0016484

Table 2. Historic (1900s, 1950s, 1970s) and contemporary (2000s) carbon isotopic signatures of penguin feathers.

	1900s		1950s		1970s		2000s
	N	δ¹³C (‰)	N	δ¹³C (‰)	N	δ¹³C (‰)	N	δ¹³C (‰)
Emperor penguin			11	−23.1±0.4 ^a	3	−23.2±0.2 ^a	17	−22.9±0.3 ^a
				−23.2 (−23.7–−22.3)		−23.2 (−23.5–−23.1)		−22.9 (−23.4–−22.3)
Adélie penguin			5	−24.2±0.4 ^a	3	−23.9±1.1 ^a	20	−23.6 ±0.5 ^a
				−24.4 (−24.5–−23.7)		−24.1 (−24.8–−22.6)		−23.6 (−24.6–−22.8)
King penguin					16	−20.5±0.6 ^a	24	−20.7±0.9 ^a
						−20.6 (−21.3–−19.5)		−20.6 (−22.0–−19.0)
Gentoo penguin					12	−19.2±1.2 ^a	24	−18.5±0.4 ^b
						−19.6 (−20.6–−17.6)		−18.4 (−19.6–−17.8)
Macaroni penguin					18	−20.8±0.6 ^a	24	−20.5±0.4 ^b
						−20.9 (−21.5–−20.0)		−20.5 (−21.0–−19.3)
Southern rockhopper penguin	2	−20.4 and −19.8			19	−20.9±0.5 ^a	54	−20.5±0.4 ^b
						−20.9 (−21.9–−20.3)		−20.5 (−21.0–−19.2)
Northern rockhopper penguin	8	−17.4±0.6 ^a	2	−18.3 and −17.8	12	−18.9±1.0 ^b	54	−17.6±0.5 ^a
		−17.3 (−18.4–−16.5)				−19.1 (−20.1–−17.2)		−17.6 (−18.7–−16.5)

First line: values are mean ± SD; second line: median, minimum and maximum values. Values in the same line not sharing a common superscript letter are significantly different (p<0.05; see text). Carbon isotopic values were corrected for Suess and increase [CO₂]_aq effects.