Black-billed swan, also known as trumpeter swan and trumpet swan, belongs to the family Anthuridae. Distributed in the United States and Canada, it likes to inhabit open and food-rich shallow waters in breeding season, and mainly inhabits lakes, ponds and rivers covered with grass in winter. With a body length of 139- 163 cm, an average wingspan of 2 10 cm and a weight of 7- 13.6 kg, it is the largest protobird in North America and the largest waterfowl in the world.

Male and female feathers are the same color, and females are slightly smaller than males. The whole body has white feathers, the mouth base is high and the front end is flat, and the eyes are exposed first. The mouth is black with a pink beak line along the bottom of the mouth. The neck is slender, exceeding or equal to the body length. When swimming in the water, the neck is vertically upward, the head is horizontally extended forward, and the wings are close to the sides, so the movement is light and slow when swimming. Tartars, flippers and claws are also black. Young birds are grayish brown, with dark head and neck, and lighter lower body, tail and flight feathers.

Sexual preference is social, and they often live in groups except during the breeding period; Especially in winter, it often shows family activities; Sometimes as many as dozens to hundreds of large groups live together. Migration usually occurs in small groups or family groups with more than 6-20 animals. When taking off, two wings beat the water constantly, and two feet ran a distance on the water to fly. When flying, the neck is straight forward and the feet are under the tail. The flying height is high, and the queue is neat, often in a "one" shape and a "V" shape.

They mainly feed on leaves, stems and seeds of aquatic plants, but also eat a small amount of mollusks and aquatic insects. The breeding season is from May to June, and the nest is built on the dry land or dry reed on the shore of lakes, ponds and islands. The nest is particularly large, and the female birds nest alone. Each nest lays 4-7 eggs, usually 4-5 eggs, and the spawning time is mostly from early May to mid-May. Hatching is undertaken by the female alone, and the male stands guard near the nest. Young birds are precocious and can follow their parents for food soon after hatching.