National Trust CJ Wildlife Premium Sunflower Hearts Wild Bird Food 1.6kgSunflower hearts wild bird food. Provide birds with the ultimate in high energy nutrition. Hearts are produced by removing the husks from black sunflower seeds which are rich in oil, so less mess in your garden and an easier meal for your birds. Garden birds use lots of energy in their daily activities. Foods rich in fats and oils will contain high calorie levels and it is these calories that provide them with the energy they need to breed, survive