天鹅指雁族（学名：Cygnus）的鸟类，属游禽，国家二级保护动物。除非洲、南极洲之外的各大陆均有分布。为鸭科中个体最大的类群。颈修长，超过体长或与身躯等长；嘴基部高而前端缓平，眼腺裸露；尾短而圆，尾羽20-24枚；蹼强大，但后趾不具瓣蹼。喜欢群栖在湖泊和沼泽地带，主要以水生植物为食，也吃螺类和软体动物。多数是一夫一妻制，相伴终生。求偶的行为丰富，雌雄会趋于一致的做出相同的动作，还会体贴地互相梳理羽毛。一年繁殖一次，卵的体积较大，如大天鹅的卵有400多克重。幼鸟为早成雏。迁徙时会多群集结，但仍是小群行动。

Swan refers to the birds of the Yan nationality (scientific name: cygnus). It is a swimming bird and a national second-class protected animal. It is distributed on all continents except Africa and Antarctica. It is the largest group of individuals in the family Anatidae. The neck is slender, exceeding the body length or equal to the body length; The base of the mouth is high and the front end is gentle and flat, and the eye gland is exposed; The tail is short and round, with 20-24 tail feathers; The web is strong, but the hind toe is not valved. They like to live in groups in lakes and swamps. They mainly eat aquatic plants, snails and molluscs. Most of them are monogamous and stay together for life. Courtship behavior is rich. Men and women will tend to make the same actions in unison, and they will considerately comb their feathers with each other. A swan's egg weighs more than 400 grams once a year. Young birds are early birds. During migration, many groups will gather, but they still act in small groups.