Table 1. Results from linear mixed models on the effects of habitat (coastal or inland), age of animal (adult or juvenile) and tissue (fur, muscle and collagen) on δ¹³C and δ¹⁵N in Icelandic arctic foxes.

Fixed effect	DF	F	P
δ13C
Habitat	1, 124	101.68	<0.001
Age	1, 124	4.48	0.036
Tissue	2, 121	168.90	<0.001
Habitat×Age	1, 124	14.87	<0.001
Habitat×Tissue	2, 121	3.33	0.039
Age×Tissue	2, 121	0.40	0.671
Habitat×Age×Tissue	2, 121	0.84	0.433
δ15N
Habitat	1, 124	83.34	<0.001
Age	1, 124	9.38	0.003
Tissue	2, 121	1.36	0.261
Habitat×Age	1, 124	17.54	<0.001
Habitat×Tissue	2, 121	1.74	0.180
Age×Tissue	2, 121	2.71	0.071
Habitat×Age×Tissue	2, 121	4.01	0.021