Original description: Passerculus princeps Maynard 1872
AOU 1 (1886): Ipswich Sparrow, Ammodramus princeps
AOU 2 (1895): Ipswich Sparrow, Ammodramus princeps
AOU 3 (1910): Ipswich Sparrow, Passerculus princeps
AOU 4 (1931): Ipswich Sparrow, Passerculus princeps
AOU 5 (1957): Ipswich Sparrow, Passerculus princeps
AOU 6 (1983): Savannah Sparrow, Passerculus sandwichensis [princeps group]
AOU 7 (1998): Savannah Sparrow, Passerculus sandwichensis [princeps group]
With a breeding population of approximately 6000 individuals, the Ipswich Sparrow is a globally rare bird; this Canadian endemic is listed by that country’s Committee on the Status of Endangered Wildlife as a vulnerable taxon of special conservation concern. Warmer average temperatures appear to contribute to breeding success on Sable Island, and the habitat there appears to be stable, “barring localized catastrophic events.” The more significant threats to this sparrow’s survival are concentrated on the wintering grounds on the east coast of the United States, where shoreline development and disturbance continue. The rising sea levels associated with global warming are likely to reduce the already very narrow strip of sandy beach along which the entire population spends the winter, and the increasing vehemence of storms in the North Atlantic is of concern in both the breeding and the wintering range.
Habitat: The habitat preferences of the Ipswich Sparrow are so pronounced as to constitute an important field character. William Brewster observed that “few of our so-called ‘shore birds’ compare with the Ipswich Sparrow in respect to the tenacity with which it clings to the seacoast.” Even on the narrowest of barrier islands, Ipswich Sparrows are more frequently found on the dunes of the ocean side than on the beaches of the nearby bay.
Behavior: Especially by the standard set by the other Passerculus sparrows, this is a fairly shy bird in the winter. Ipswich Sparrows feed quietly in the dunes, walking and sometimes running beneath the beach grass and flushing reluctantly once they are convinced they have been seen. Disturbed birds may fly more than 100 yards before landing on the dune top and scampering back into the sparse cover.
Though they do sometimes emerge to feed on the open edge of the dunes, Ipswich Sparrows are most reliably seen and watched at leisure when they perch, sometimes for minutes at a time, on the large rocks of jetties and breakwaters. A classic wintertime sight in New England and the mid-Atlantic states is a tightly clustered flock of Purple Sandpipers and Ruddy Turnstones with a lone Ipswich Sparrow at their side.
Voice:On the breeding grounds, male Ipswich Sparrows sing from any elevated site, including dune tops, short shrubs, and posts.
Detailed description and measurements drawn from standard reference works
Adult: Tail feathers brown-gray with paler gray edges on the outer vanes; all tail feathers with attenuated tips. Upper tail coverts with fine cinnamon-bordered black shaft streaks and soft gray edges; rump feathers more extensively gray. Ground color of the back and scapulars gray, with broad blackish shaft streaks bordered dull chestnut. Primaries dull gray-brown with paler outer edges. Secondaries browner, but not deep chestnut. Tertials black with broad pale brown edges and whitish tips. Greater coverts dull brown with grayer tips and blackish teardrops; faint wing bar discernible in fresh plumage. Nape gray with fine cinnamon streaking. Underparts dull white, brightest on throat; breast and, especially, flanks often with faint buffy wash. Streaking of underparts fine, sparse, and irregular, made up of very narrow black shaft streaks narrowly bordered with pale cinnamon-brown. White throat unmarked or lightly marked, bordered by narrow, streaked lateral stripe barely or not at all reaching bill base. Broad jaw stripe white, sometimes washed buffy. Crown gray, broad lateral stripes streaked pale brown and black; narrow median stripe dull whitish, broadest towards bill base. Ear coverts pale gray, bordered below by thin, poorly defined brown whisker and above by thin, poorly defined brown eye line. Broad silvery supercilium, whitish in front of eye, with yellow tinge in late winter and spring. Narrow whitish eye ring barely broken by brown eye line. Bill pink-brown, with extensively dark culmen. Tarsus and toes yellow-brown with pink tinge.
Juvenile: Buffy above, paler on back, with narrow black-brown streaks on rump, back, nape, and crown. Yellowish-buff below, with narrow black-brown streaks on throat, breast sides, and flanks. Primaries, secondaries, and greater coverts with pale cinnamon edges; tertials rusty. Bill and tarsus pinkish, darkening to brown in older juveniles.
Length 149-156 mm (5.9-6.1 inches)
Wing chord 71-76 mm (2.8-3.0 inches)
Tail 55-59 mm (2.2-2.3 inches)
Mass 24-33 g