The Saltmarsh Sharp-tailed Sparrow, Ammodramus caudacutus, is a small sparrow. At one time, this bird and the Nelson's Sharp-tailed Sparrow were thought to be a single species, the Sharp-tailed Sparrow.

Adults have brownish upperparts with grey on the crown and nape, a cream-coloured breast with dark streaks and a white throat and belly; they have an orange face with grey cheeks and a short pointed tail.

Their breeding habitat is salt marshes on the Atlantic coast of the United States from southern Maine to Virginia. The nest is an open cup located above the high tide line. Males compete for females but do not defend territories. Only females raise the young.

These birds migrate further south along the eastern coast of the United States.

They forage on the ground or in marsh vegetation, sometimes probing in mud. They mainly eat insects, aquatic invertebrates and seeds.

The call is a raspy trill.

This bird's numbers are declining due to habitat loss.