Table 1.

Discrimination factors (ΔC and ΔN) for rat livers calculated with the diet‐dependent discrimination factor method for each rat food item (See Appendix S1). These discrimination factors were used for analysis with the Isosource isotopic model (Phillips & Gregg 2003)

Rat food items	November 2004		February 2005
	ΔC	ΔN	ΔC	ΔN
Skinks	–1·77	–0·03	–0·36	0
Insects (I)	–2·89	0·80	–3·43	1·56
Insects (II)	1·07	0·80	1·22	0·87
Plants C4/CAM	–2·78	2·09	–2·81	2·15
Plants C3	1·21	2·73	0·75	2·80
Sea turtles			–1·65	2·26
Seabirds	–0·84	1·49