美洲鸵鸟（学名Rhea americana），别名三趾鸵鸟或鶆䴈，是美洲最大鸟类，不能飞行，脚上有3枚向前的趾。美洲鸵鸟分布于南美洲广阔的草原上，体长约150公分，食物为植物种子、根和昆虫。

美洲鸵鸟喜欢结群生活，一雄多雌婚配制度，两性的羽色十分相似，雄鸟小于雌鸟，1只雄鸟和5至6只雌鸟在一起，同它们的后代结成20至30只的大群生活。

2001年世界青年足球锦标赛在阿根廷举行，以一只顽皮的雄性美洲鸵鸟来作吉祥物，取名「南迪」。

The greater rhea (Rhea americana) is a flightless bird found in eastern South America. Other names for the greater rhea include the grey, common, or American rhea; ñandú (Guaraní); or ema (Portuguese). One of two species in the genus Rhea, in the family Rheidae, the greater rhea is endemic to Argentina, Bolivia, Brazil, Paraguay and Uruguay. It inhabits a variety of open areas, such as grasslands, savanna or grassy wetlands. Weighing 20–27 kilograms (44–60 lb), the greater rhea is the largest bird in South America. In the wild, the greater rhea has a life expectancy of 10.5 years. It is also notable for its reproductive habits, and for the fact that a group has established itself in Germany in recent years. The species is listed as Near Threatened by the IUCN.