美洲小鸵（Rhea pennata），又名达尔文鶆䴈，是现存美洲鸵鸟属最细小的物种。

美洲小鸵高90-100厘米，重15-25公斤。牠们的翼较其他鸵鸟大，故奔跑得很好。牠们最高速可达每小时60公里，可以脱离掠食者的追捕。牠们的爪很锋利，是很有效的武器。牠们的羽毛有褐色及白色的斑点，上肢也有羽毛。

Darwin's rhea (Rhea pennata), also known as the lesser rhea, is a large flightless bird, but the smaller of the two extant species of rheas. It is found in the Altiplano and Patagonia in South America.