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Saltmarsh Sparrow

Ammospiza caudacuta
Passerellidae
Orange head and fine streaks on buff breast
Until 1995, it was called the Sharp-tailed Sparrow ...
... along with Nelson's Sparrow which ...
... also has sharp tail feathers
Other sparrows, like this Swamp Sparrow, have rounded feathers
Saltmarsh Sparrow has fine streaks on buff breast
Nelson's Sparrow has orange breast distinct from white belly
Saltmarsh Sparrow is well-adapted to living in tidal habitat
Breeding activities timed to avoid tidal flooding of low-lying nest
Clutch of 3-6 eggs timed to avoid tidal extremes
Parent with full beak of insects intended for nestlings
Enough time to become mobile before next high tide?
Mobile chick can escape extreme high tides
Despite successful adaptations, future is very gloomy
Rising sea level is reducing extent of Atlantic salt marshes ...
... that are crucial for breeding ...
... migration stopovers ...
... and wintering grounds

The Saltmarsh Sparrow is a rare visitor to Salter Grove.  Based on available data for the park from 2002 to 2023, there has been only one sighting in mid-August, 2016.  This species breeds exclusively in the coastal salt marshes that stretch from Maine to Virginia.  The lone visitor was likely a migrant from Maine or Massachusetts on its way to winter in coastal marshes from North Carolina to Florida.

The Saltmarsh Sparrow can be confused with Nelson's Sparrow, a sister species which has been an equally rare visitor to Salter Grove.  Both species favor dense marsh vegetation for all their activities, so it is a challenge to observe, much less distinguish between them in areas of co-occurrence.

Both sparrows have vibrant yellowish-orange plumage in the head area.  However, the Saltmarsh Sparrow has buff underparts whereas the orange tinge in Nelson's Sparrow extends from the head down to meet a distinct white belly.  The underparts of the Saltmarsh Sparrow are marked with thin and distinct dark streaks while the Nelson's Sparrow has thicker brown streaks that are blurry.

The Saltmarsh Sparrow was once lumped together with Nelson's Sparrow as the Sharp-tailed Sparrow.  In 1995, the American Ornithologist' Union separated the two species in its Checklist of North American Birds on the basis of differences in song, morphology, and habitat.  Subsequent analyses of mitochondrial DNA suggested that the two species were probably separated some 600,000 years ago by glaciers during the Pleistocene into an inland population and a coastal population.

Since the glacial separation, the Saltmarsh Sparrow became a specialist of tidal salt marsh whereas Nelson's Sparrow became a specialist of freshwater wetland.  Comparative studies in Rhode Island and elsewhere showed a difference in their reproductive success in tidal habitat.  Both species nest on or near the ground so risk losing eggs and nestlings to extreme high tides.  In coastal marshes where both species breed, the Saltmarsh Sparrow enjoys higher reproductive success because the timing of its reproductive activities have adapted to regular inundation of the nesting habitat.

However, its specialization may also lead to its demise.  Long term prospects for the Saltmarsh Sparrow are gloomy.  Researchers predict its extinction by 2050 because of its total dependence on Atlantic coastal salt marshes for its livelihood.

Human activities have greatly reduced suitable habitat and rising sea level has accelerated further losses.  The U.S. Fish and Wildlife Service and various nongovernmental organizations in Massachusetts, New York, and Rhode Island have intensified studies in the past decade to identify measures that can preserve at least some suitable nesting habitat for this extremely vulnerable species.