Saltmarsh Sparrow

The Saltmarsh Sparrow, Ammospiza caudacuta, is a diminutive New World sparrow, inhabiting the salt marshes of the Atlantic coast of the United States. This bird, once considered conspecific with the Nelson's Sparrow and known as the "saltmarsh sharp-tailed sparrow," is now recognized for its distinctiveness. It is characterized by its brownish upperparts, a gray nape, and a white underbelly. The breast and sides are a soft pale orange, adorned with brown streaks. The face features an orange hue with gray cheeks, and the crown of the head is marked by a gray median stripe flanked by brown. The tail feathers are notably short and sharply pointed.

Identification Tips

When identifying the Saltmarsh Sparrow, look for the orange face with gray cheeks, the gray median crown stripe, and the brown lateral crown stripes. The brown eyeline is also a distinguishing feature. The subspecies A. c. diversa exhibits more pronounced striping on the back and a darker crown compared to the nominate form.

Habitat

The Saltmarsh Sparrow's habitat is restricted to tidal salt marshes along the Atlantic coast. It shows a preference for high marsh areas, where the vegetation is dominated by saltmeadow cordgrass and saltmarsh rush, which are less frequently inundated than the lower marsh zones.

Distribution

This species breeds in the northeastern United States, from Maine to the Chesapeake Bay, and winters from North Carolina to Florida. It is a bird of the coast, never straying far from the salty air of its marshland home.

Behaviour

Males of the Saltmarsh Sparrow are known to be promiscuous, with large overlapping home ranges. They are non-territorial and exhibit a roaming behavior during the nesting season. Females are solely responsible for nest building, incubation, and feeding of the young.

Song & Calls

The male Saltmarsh Sparrow's song is a complex and subtle series of buzzes, trills, and gurgles, often difficult to detect. It is distinct from the Nelson's Sparrow's louder, hissing buzz followed by a buzzy chip. The high-pitched contact calls of both species are, however, indistinguishable.

Breeding

Breeding Saltmarsh Sparrows are adapted to their flood-prone environment. They time their nesting to the lunar cycle, beginning immediately after a spring tide to allow fledging before the next. Nests are open cups of grass, attached to the sturdy stems of marsh vegetation. Females lay clutches of 3 to 5 eggs, with incubation lasting 11-12 days and fledging occurring 8-11 days post-hatching.

Similar Species

The Saltmarsh Sparrow can be confused with the Nelson's Sparrow. The inland subspecies of the Nelson's Sparrow has fainter streaking and a brighter orange breast, while the coastal subspecies has paler, less contrasting plumage. The Saltmarsh Sparrow also possesses a slightly longer beak.

Diet and Feeding

The diet of the Saltmarsh Sparrow is primarily composed of insects such as flies, amphipods, grasshoppers, and moths, with a particular preference for the various life stages of soldier flies. In winter, seeds supplement its diet. This bird forages on the ground or in marsh vegetation, often probing the mud at low tide.

Conservation status

The Saltmarsh Sparrow is classified as Endangered by the IUCN and Imperiled by NatureServe. Its populations are in decline, primarily due to habitat loss from human activity and sea level rise. The invasive reed Phragmites has also contributed to habitat degradation. The species is sensitive to mercury bioaccumulation, though the impact on survival is not fully understood. Current estimates suggest a population of approximately 53,000 individuals, with projections indicating potential extinction by 2050 without conservation intervention.