In "The Ugly Duckling," a young bird is mistaken for a duck until it grows up to be a beautiful swan. A swan is a large bird with a long, elegant neck.
You're most likely to see swans in the water, but they also spend some time on land. Baby swans are called cygnets, and as adults, they're either cobs (if male), or pens (if female). If you're lucky enough to see a whole group of swans swimming or flying together, you can call it a bevy of swans. Swan comes from a root meaning "to sing."