What does Yuanyang mean in the quatrains?

Yuanyang in the quatrains is a kind of bird. It looks like a wild duck, but smaller, with a flat mouth, a long neck and webbed toes. It is good at swimming, has long wings and can fly. Male birds have colorful feathers, long crested hairs of copper, red, purple and green behind their heads, and their mouths are red. Female birds have hazel feathers and grayish-black mouths, and most of them are in pairs.

Later that day, Jiang,

Spring breeze smells of flowers and plants.

Muddy swallows,

Sleeping mandarin ducks on the warm beach.