鸿雁（Anser cygnoides），亦名原鹅、大雁、洪雁、冠雁、天鹅式大雁、随鹅、奇鹅、黑嘴雁、沙雁、草雁。

体形较大的雁，颈长。黑且长的嘴与前额成一直线，环绕嘴基的额部有一条很狭窄的棕白色条纹，嘴裂基部有两条棕褐色的鹗纹。上体灰褐但羽缘皮黄。头顶及颈部背侧正中棕褐，前颈白色，与后颈有一道明显界线，这种前白后棕的鲜明对比是鸿雁区别于雁属其他种类的显着特征。本种最长的尾上覆羽纯白，余者与腰同色，尾羽灰褐，先端及边缘白色，初级飞羽外羽片灰褐，内羽片暗褐，羽干象牙白色，次级飞羽暗褐色。与小白额雁及白额雁区别在于嘴为黑色，额及前颈白色较少。 虹膜褐色；嘴黑色；脚深橘黄。 飞行时作典型雁叫，升调的拖长音。

The swan goose (Anser cygnoides) is a rare large goose with a natural breeding range in inland Mongolia, northernmost China, and southeastern Russia. It is migratory and winters mainly in central and eastern China. Vagrant birds are encountered in Japan and Korea (where it used to winter in numbers when it was more common), and more rarely in Kazakhstan, Laos, coastal Siberia, ******, Thailand and Uzbekistan.