Harrisons Wild Bird Food Sunflower Hearts. This edible kernel of the sunflower seed, offers the highest calorific value of any individual seed for wild birds. They are both irresistible and 100% edible, leaving very little mess in the garden. This is an excellent very high energy content food with year round appeal for a wide variety of birds. Whether it is fed from a seed feeder, table or the ground top ups will be needed far more frequently than with most other bird foods to retain the high le