Introduction

The Seaside Sparrow is a habitat specialist of salt and brackish marshes. First described by Wilson (1811), it has attracted the interest of systematists since the end of the nineteenth century. Occurring in relatively small, localized populations along the Atlantic and Gulf Coasts of the United States, this species has been divided into several morphologically distinct subspecies.

This sparrow is monogamous throughout its range. Although territorial, it often feeds long distances from the defended space around its nest, a response to wide separation of nesting and feeding areas in the tidal zones it inhabits. Under optimal conditions, it may occur at high population densities, a reflection of the high productivity of salt marshes. Optimal habitat is found in marshes with expanses of medium-high cordgrass with a turf of clumped, residual stems. Especially suitable are spots not subject to extreme flooding that have open muddy areas for feeding. Nest mortality of northern populations is low and is caused mainly by storm flooding; southern groups have low reproductive success, mainly because of high levels of rodent predation.

As a maritime wetland specialist, the Seaside Sparrow represents a potentially valuable “indicator” of continued ecological integrity of certain types of coastal marshes and has already proven sensitive to habitat modification in Florida. The melanistic Dusky Seaside Sparrow (A. m. nigrescens) of east-central Florida is extinct; the pale Cape Sable Seaside Sparrow (A. m. mirabilis) of the Florida Everglades is endangered. Other populations are as likely to be susceptible to habitat disturbance and restriction as those in Florida. Although the species has been studied in detail in the Northeast (Woolfenden 1956, Post et al. 1983) and Florida (Post et al. 1983, Werner and Woolfenden 1983), little is known about its distribution and habitat requirements on the southeast Atlantic and northern Gulf of Mexico coasts.