Adult Diet

• The diet of black swans consists of algae and all parts of underwater plants, from the roots to the leaves. They'll graze on grass that grows at the edge of bodies of water. They will also sometimes eat worms, insects, small aquatic animals and grain.
  
  

Cygnet Diet

• Wild cygnets (baby swans) mostly eat insects and small invertebrates they find on the water's surface. They will sometimes eat seeds. If hand-raised, cygnets can be given starter pellets, chopped green food and hard-boiled egg, according to the Wildlife Information Network.
  
  

Eating Habits

• Fine grooves in black swans' bills grip the plants they find underwater, according to Blank Park Zoo. To get to their food source, black swans will reach their long necks down to it, sometimes tipping their tail up. They prefer shallow water where they can reach the bottom.