Table 2. Statistical comparison of δ¹³C and δ¹⁵N between various tissues of individual herbivorous waterbirds.

Tissue	Isotope	Blood cells		Claw		Back feather		Primary feather
		t	p	t	p	t	p	t	p
Plasma	C	8.74	0.001	−1.79	0.10	−3.52	0.003	−3.84	0.001
	N	7.16	0.001	0.14	0.89	−4.39	0.001	−6.45	0.001
Blood cells	C			−7.16	0.001	−6.81	0.001	−14.04	0.001
	N			−10.11	0.001	−10.20	0.001	−20.57	0.001
Claw	C					−1.66	0.12	−2.04	0.06
	N					−2.37	0.04	−9.53	0.001
Back feather	C							0.84	0.41
	N							−3.73	0.002

Tissues are blood plasma, blood cells, and keratinous tissues: claw, back feather and first primary feather from Bewick Swans (Cygnus columbianus bewickii, n = 9) and mallards (Anas platyrhynchos, n = 9). Data were pooled for paired t-tests.