Saltmarsh sparrow numbers are declining due to habitat loss largely attributed to human activity.

The saltmarsh sparrow was formally described in 1788 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae.

[12] Recently, the Nelson's sparrow has expanded its range to include coastal salt marshes, and interbreeding occurs where the two species overlap.

[15][16] Adults have brownish upperparts with a gray nape, white throat and belly, and pale orange breast and sides with brown streaking.

[17] The saltmarsh sparrow is only found in tidal salt marshes along the Atlantic coast of the United States.

[20] The saltmarsh sparrow forages on the ground along tidal channels or in marsh vegetation, sometimes probing in the mud at low tide.

Only females exhibit parental care, building the nest, incubating the eggs, and providing food to the young.

[12] The nest is an open cup constructed of grass, usually attached to saltmeadow cordgrass (Sporobolus pumilus) or saltmarsh rush (Juncus gerardii) at a height of 6–15 centimetres (2.4–5.9 in).

[19] The primary cause of nest mortality is flooding due to storm surges and periodic, exceptionally high spring tides which occur every 28 days during the new moon.

The saltmarsh sparrow exhibits several adaptations to flooding, including nest repair, egg retrieval, rapid re-nesting, and synchronization of breeding with the lunar cycle.

[19] The saltmarsh sparrow is of high conservation concern due to habitat loss resulting in small fragmented populations.

[19][26] Salt marshes are one of the most threatened habitats worldwide due to their limited natural extent, long history of human modification, and anticipated sea level rise.