Table 4. Mean dry mass (g ± SD) and mean energy value (kJ) of nine food items gathered by sub-adult and adult Ring-billed Gulls in three habitat types (N = number of birds with food items present in their stomach).

	Mean dry mass (g)
Food items	Landfills	Agricultural lands	Riparian habitats	Energy
	(N = 81)	(N = 54)	(N = 22)	(kJ)
Meat	1.84±4.71	-	0.87±2.81	30.1
Bread/rice	1.27±2.62	-	0.47±1.05	19.9
Potatoes/French fries	0.15±0.79	-	0.32±0.89	21.8
Miscellaneous refuse	0.79±2.69	-	-	22.6
Annelids	0.10±0.32	1.99±2.80	-	13.8
Arthropods	0.06±0.24	0.03±0.08	0.09±0.24	22.8
Corn/soybean grains	-	1.44±3.36	-	18.1
Vertebrates	0.01±0.11	-	0.46±0.61	19.4
Miscellaneous	0.10±0.32	0.08±0.35	-	21.3
TOTAL	4.47±6.37	3.55±3.68	2.36±3.39	-