On the edge of the Atlantic coast, the Saltmarsh Sharp-tailed Sparrow lives in a shrinking ribbon of grassland. This bright-faced songbird usually prefers to run or clamber through the marsh, rather than to fly over it. The Saltmarsh and Nelson's Sharp-tailed Sparrows were considered a single species until 1995. The separation into two speciesfocused attention on the plight of the Saltmarsh Sharp-tailed Sparrow's habitat and the need to better understand its biology.
At 5.25 inches long, Saltmarsh Sharp-tailed Sparrows weigh .67 ounces with a 7-inch wingspan. A satisfying look at a Saltmarsh Sharp-tailed Sparrow requires devotion and magnification. This small, compact perching bird often appears flat-headed, with no neck. The plumage is complex and bold. Thick orange-yellow lines form an inverted triangle around each gray ear and dark eye. Behind the eye, a brown line pierces this ochre color to connect the eye to the gray nape. A dark cap and whitish throat frame this pattern. Distinct among the brown and black streaks of the upper parts are four jagged, white streaks. The lower parts are mostly whitish, with a little warm color washed over the thin, dark streaks of the breast.
Confined to coastal marshes, the Saltmarsh Sharp-tailed Sparrow breeds from southern Maine just into North Carolina (Pea Island). Its populations are most dense in the marshes of Long Island south to the Delmarva Peninsula. The Saltmarsh Sharp-tailed Sparrow's range overlaps with its close relative, the Nelson's Sharp-tailed Sparrow, with which it may interbreed, from northeastern Massachusetts through the end of its range in southern Maine. This small sparrow winters coastally from Maryland south to the Atlantic mid-coast ofFlorida. It rarely occurs on Florida's Gulf Coast.
A legend for the range map to the right can be found
here.
For breeding, Saltmarsh Sharp-tailed Sparrows need large maritime wetlands around estuaries and barrier islands. Course grasses like spartina and blackgrass dominate these open salt marshes, leaving muddy spaces between the grass tufts. The sparrows winter in similar habitat—sometimes in the same area.
The Saltmarsh Sharp-tailed Sparrow forages actively through grasses and over the wet marsh floor. Hunting by sight, this sparrow walks, runs, hops, and jumps after prey. Its breeding season diet consists of small crabs, small mussels, and adult and immature insects—including beach fleas, beetles, flies, and moths. As annual plants ripen in the marsh, the sparrow's diet shifts to include seeds from cordgrass, dandelions, saltbush, and smartweed. The Saltmarsh Sharp-tailed Sparrow climbs grass stems to pull seeds from their husks.
The Saltmarsh Sharp-tailed Sparrow's breeding behaviors are remarkable and unusual. Males assemble on the breeding grounds but do not defend territories or bond with arriving females. Females are attracted by songs and chased by males in a competitive scramble to mate. Females assume all nesting and chick-rearing tasks. Saltmarsh Sharp-tailed Sparrows appear to time their nesting to avoid high tides, which can kill eggs.
The female usually builds a grassy nest attached to grass stems over mud or water, and covered by loosely intertwined grass blades. She lays two to six greenish to bluish eggs, densely speckled with browns. The young hatch in about 12 days. Fed insects and small crustaceans, the naked, helpless chicks develop quickly, leaving the nest in about ten days to hide in the grass. Two to three weeks later, the independent young flock with other juvenile Saltmarsh Sharp-tailed Sparrows. Most females south of Massachusetts will then raise another brood.
The timing and behavior of Saltmarsh Sharp-tailed Sparrow migration has not been well separated from that of the Nelson's Sharp-tailed Sparrow. The Saltmarsh Sharp-tailed Sparrow withdraws from its breeding range almost entirely and migrates short to medium distances. During migration and winter, this sparrow may be found in groups.
Gjerdrum C., Elphick C. S., andRubega M. "Nest site selection and nesting success in salt marsh breeding sparrows: The importance of nest habitat, timing, and study site differences."
The Condor 107:4 (2005) p. 849-862.
Greenlaw, J. S. and J. D. Rising. 1994. Sharp-tailed Sparrow (
Ammodramus caudacutus). In
The Birds of North America, No. 112 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington, D.C.: The American Ornithologists' Union.
Sibley, David Allen.
The Sibley Guide to Birds. Alfred A. Knopf, New York. 2000.
