Written by Bryan Watts & Fletcher Smith
July 2, 2010
The saltmarsh sparrow (Ammodramus caudacutus) is a species of high conservation concern due to its extremely limited global distribution, its complete dependence on salt marshes, and the vulnerability of these marshes to sea-level rise. The species is confined to the narrow ribbon of salt marsh habitat on the outer coast of New England and the mid-Atlantic. The saltmarsh sparrow is comprised of 2 forms including A. caudacutus caudacutus (northern form) that breeds along the coast from Maine south to New Jersey and A. c. diversus (southern form) that breeds along the coast from New Jersey south.
Historically, there has been considerable confusion over the southern range-limit for breeding in this form. Since 1957, the American Ornithologists’ Union (AOU) Checklist of North American Birds has indicated that this form breeds from Maine south to Pea Island North Carolina. The placement of the southern range limit was apparently based on a nestling collected by Paul Bartsch on 2 July 1938 from Pea Island. Examination of this material later revealed that the specimen had been mislabeled/misidentified and was relabeled as a seaside sparrow (Ammodramus maritimus). Subsequent attempts by numerous investigators to locate breeding populations in coastal North Carolina have not been successful suggesting that the southern range limit occurs in coastal Virginia.
Harold H. Bailey (1913) indicates that during his era, sharp-tailed sparrows were common breeders along the upper western shore of the Chesapeake Bay in Virginia. The only modern breeding record within this area is a nest with 4 eggs found in Four Points Marsh in Gloucester County by Bryan Watts in 1992. This observation was made as part of a survey of more than 50 marsh patches within the area. Stewart and Robbins in the 1940s and 1950s documented the species along the western shore of Maryland. By the time of the Maryland breeding bird atlas (1983-1987), this population had disappeared with only a single bird observed near Sandy Point.
Over the past decade, CCB has conducted several investigations of marsh birds along both the bayside and seaside of the Delmarva Peninsula. These surveys along with other observations place the current range limit for breeding on both sides of the peninsula very close to the Northampton-Accomack County border. This location is a transition point along the peninsula. Moving northward from here, the marshes become more extensive and considerably higher in elevation matching the habitat requirements for breeding.
Project sponsored by the Center for Conservation Biology (CCB).