Seaside Sparrow Ammospiza maritima Scientific name definitions

Jon S. Greenlaw, W. Gregory Shriver, and William Post
Version: 2.0 — Published July 1, 2022



Breeding Range

Tidal marshes along Atlantic coast of United States, from southern Maine (rarely) to extreme northeastern Florida, north of St. Johns River in Duval and Nassau counties, with disjunct populations (A. m. mirabilis) in freshwater inland marshes of southern Florida (Monroe and Miami-Dade counties) within Everglades National Park and Big Cypress National Preserve, and extending irregularly along Gulf coast from west-central Florida (Pasco County) to lower Rio Grande Valley, Texas (Cameron County). A molting juvenal south of Rio Grande in Tamaulipas, Mexico, may indicate breeding there (79, eBird).

Throughout range, populations mostly are distributed linearly along the coast and are separated into isolated demes by open water and by areas of unsuitable habitat, but a habitat gap evidently separates the populations in the area of Corpus Christi, Texas, and the recently discovered population in Cameron County, Texas (52, 12). Another habitat gap suggested along the Gulf coast farther east from the Alabama border to the Franklin County area of Florida (12) may not be accurate. Duncan and Duncan (101) noted that a small population at Garçon Point in Santa Rosa County, Florida, may be of A. m. fisheri based on specimens taken there by F. M. Weston.

At northern limit of range, local and rare in summer in southern Maine, especially at Scarborough Marsh (60); similarly rare in New Hampshire, where apparently confined to Hampton marshes (102). In Massachusetts (103, 104), a local, uncommon, disjunct breeder in salt marshes (e.g., Westport/South Dartmouth; Barnstable on Cape Cod; Plum Island in Parker Island National Wildlife Refuge; and near Newburyport). More widely distributed and abundant southward, such as on Long Island, New York (105), and in New Jersey, where especially common on southern Atlantic coastal marshes and along Delaware Bay (106, 107). During the second Breeding Bird Atlas in Maryland (2002–2006), found only in salt marshes on the east side of lower Chesapeake Bay in Dorchester, Wicomico, Somerset, and Queen Anne's counties (108).

Overwintering Range

Similar to breeding range. Northeastern populations (New Hampshire to New Jersey) are migratory or partially migratory and probably overwinter primarily in North Carolina and South Carolina and possibly farther south. Pale individuals are similar to A. m. maritimus are indistinguishable from many pale variants of A. m. macgillivraii, so plumage is not helpful for distinguishing northern migrants from southern residents. Small numbers of northeastern birds overwinter irregularly in breeding range from southern New England and New York south. A breeding population near Charleston, South Carolina (A. m. macgillivraii), winters in coastal tidal marshes, but in spring adults move inland to breed along rivers in brackish marshes to Hanahan (Berkeley County), about 23 km from wintering marshes on Sullivan Island (109); see also Davis et al. (12). No evidence of sex- or size-based trends in wintering populations based on evidence from mist-netting transects of tidal marshes extending from North Carolina to Florida (110).

Historical Changes to the Distribution

Although the overall extent of the range has changed little, human activity has altered habitat that has lead to extinctions of localized subspecies and there are now larger local gaps in distribution relative to historical times. See Robbins (50) for a discussion of the history of ornithological understanding (and misunderstanding) of the distribution of the species and its subspecies. Most of the historical changes in Robbins' map (his Figure 1) represented reassessments of subspecies status and limits based on additional collections of specimens. However, one change in the southern range of A. m. peninsulae on the Florida Gulf coast concerned a range retraction that occurred after Allen's time (1988) from the Tampa Bay marshes and those near Tarpon Springs, which no longer exist where high density urbanization and mangrove intrusion are typical today (111, 80).

On the Atlantic Coast, populations south of northeastern Florida (Duval County) are extinct (subspecies A. m. pelonota and A. m. nigrescens). The Cape Sable Seaside Sparrow (Ammospiza maritima mirabilis) population in the Cape Sable coastal marsh was apparently destroyed by a hurricane in 1935 (112); this subspecies now inhabits Muhlenbergia grass-dominated, marl prairie up to 40 km inland from Gulf coast (9). Farther north, the breeding range had expanded slightly northward, from Massachusetts into New Hampshire by 1985 (113) and rarely to southernmost Maine (60). The second Atlas of breeding birds in Maryland and District of Columbia found a retraction of range from entire west shore and from northern section of east shore of Chesapeake Bay (108) relative to its distribution in 1958 (114).

An isolated population of A. m. sennetti was recently discovered breeding at Laguna Atascosa National Wildlife Refuge in extreme southern coastal Texas (Cameron County) (77, 78), but is almost certainly not a range extension from the Corpus Christi area. This population is genetically distinct from populations near Corpus Christi and farther north on the Texas coast (51, 52), and their habitat is unique (52; see Habitat).

Distribution of the Seaside Sparrow - Range Map
  • Year-round
  • Migration
  • Breeding
  • Non-Breeding
Distribution of the Seaside Sparrow
Seaside Sparrow, Abundance map
The Cornell Lab logo
Data provided by eBird

Seaside Sparrow

Ammospiza maritima


Relative abundance is depicted for each season along a color gradient from a light color indicating lower relative abundance to a dark color indicating a higher relative abundance. Relative abundance is the estimated average count of individuals detected by an eBirder during a 1 hour, 1 kilometer traveling checklist at the optimal time of day for each species.   Learn more about this data

Relative abundance
Breeding season
May 17 - Aug 17
Non-breeding season
Dec 7 - Mar 22
Pre-breeding migratory season
Mar 29 - May 10
Post-breeding migratory season
Aug 24 - Nov 30
Note: Seasonal ranges overlap and are stacked in the order above; view full range in season maps.
Seasons timeline
Learn more about seasons

Recommended Citation

Greenlaw, J. S., W. G. Shriver, and W. Post (2022). Seaside Sparrow (Ammospiza maritima), version 2.0. In Birds of the World (P. G. Rodewald and B. K. Keeney, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.seaspa.02