What do Whooper swan eat in the winter?

Do penguins build their nests out of rocks? Why shouldn't you save the condor? Do eagles eat herring? How do you stop a lorikeet parrot from chewing window mesh from outside my home? Why do water birds flock to dams? What is the Parrot ck3100 used for? Is a bald eagle a thing or person? What colors are quails? Can quail eggs get wet? What adaptation does a migrating birds have? Are ostriches nocturnal? How does the courtship method of a swan differ from that of a peacock? Why does your duck bob her head up and down? What non native bird has competitively excluded bluebirds and various woodpeckers from their habitat? Which of the following would be the best method for randomly determining how many eggs an imaginary bird lays in a simulation? What black bird has longish yellow legs red beak and a few white tail feathers? What is the color of mirfak? Why might woodpeckers with long beaks have a selective advantage over those with shorter beaks? Can you eat duck if you got gout? What is the cockatiel's most dangerous predator?

What do Whooper swan eat in the winter?