The saltmarsh sparrow (Ammodramus caudacutus) is a small American sparrow. At one time, this bird and the Nelson's sparrow were thought to be a single species, the sharp-tailed sparrow. Because of this, the species was briefly known as the "saltmarsh sharp-tailed sparrow".The saltmarsh sparrow measures 11–14 cm (4.3–5.5 in) in length, spans 17.8–21 cm (7.0–8.3 in) across the wings and weighs from 14–23.1 g (0.49–0.81 oz).