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Saltmarsh Sparrow

Ammospiza caudacuta

Order:
Passeriformes
Family:
Passerellidae
Sections

Distribution, Migration, and Habitat

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Figure 1. Distribution of Saltmarsh Sparrow.
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eBird range map for Saltmarsh Sparrow

Generated from eBird observations (Year-Round, 1900-present)

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Figure 4. Detail of Saltmarsh Sparrow distribution.

Purple line in winter from Cape Cod southward signifies irregular (frequently absent) occurrence in specific coastal marshes by a few individuals (typically 1-3), often only in early winter.

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Figure 5. Breeding habitat of the Saltmarsh Sparrow.

Typical salt-marsh habitat of the Saltmarsh Sparrow along the southern coast of New England. Photos by M. Male (top) and A. Poole (bottom).

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Example of Saltmarsh Sparrow breeding habitat.

Saltmarsh Sparrow Connecticut breeding habitat, in spring.

© Alyssa Borowske, Connecticut, United States, 13 May 2013
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Example of Saltmarsh Sparrow breeding habitat.

Saltmarsh Sparrow Connecticut breeding habitat, high tide. Waterford, CT.

© Alyssa Borowske, Connecticut, United States, 30 June 2010
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Example of Saltmarsh Sparrow breeding habitat.

Saltmarsh Sparrow Connecticut breeding habitat, low tide. Waterford, CT.

© Alyssa Borowske, Connecticut, United States, 30 June 2010
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Example of Saltmarsh Sparrow breeding habitat.

Saltmarsh Sparrow Connecticut breeding habitat, Stonington, CT.

© Alyssa Borowske, Connecticut, United States, 6 August 2013
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Example of Saltmarsh Sparrow breeding habitat.

Saltmarsh Sparrow Connecticut breeding habitat, Stonington, CT.

© Alyssa Borowske, Connecticut, United States, 30 July 2012
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Example of Saltmarsh Sparrow breeding habitat.

Saltmarsh Sparrow Connecticut breeding habitat, in fall.

© Alyssa Borowske, Connecticut, United States, 18 October 2013
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Example of Saltmarsh Sparrow overwintering habitat.

Saltmarsh Sparrow South Carolina winter habitat. Georgetown, SC.

© Alyssa Borowske, South Carolina, United States, 2 March 2014
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Figure 2. Annual cycle of Saltmarsh Sparrow breeding, migration, and molt.

Thick lines show peak activity, thin lines off-peak activity. The lines for breeding and migration reflect average timing across range, but local peak and off-peak timing varies between northern and southern parts breeding range. Earliest migrants may be individual outliers. Molt initiation can vary depending on end of most breeding activity (primary sources: Hill 1965, Winder 2012; JSG, New York; WP, South Carolina; P. Pyle, molt, based on specimens. In New York, we found no evidence of body molt in early arrivals of local individuals on breeding grounds, latest April-early May; JSG banding notes). See text on migration chronology.

Distribution in the Americas

Breeding Range

Among passerines, this species is unique in being restricted to tidal salt marshes (79), which form a linear and highly fragmented range bordering sheltered coasts. It breeds on the northern Atlantic coast of the United States from South Thomaston, Knox County, Maine, south to the Delmarva Peninsula and the lower Chesapeake Bay, eastern Maryland and northeastern Virginia (27, 80, 64, 81; Figure 1). In Maryland, Breeding Bird Atlas projects in 1983–1987 and 2002–2006 confirmed breeding at the southern end of its range around Chesapeake Bay in Dorchester County (Fishing Bay) and in Somerset County (mouth of Chesapeake Bay), and in Chincoteague Bay in Worcester County on the Atlantic coast (82, 83). In Virginia, breeding is known in Accomac County (Chincoteague Bay, Wallops Island), Northampton County (south to Red Bank), and in Gloucester County on the western shore of Chesapeake Bay (84, 85, 81). This last location may be the most southern outpost within its breeding range. From Accomac County, where the species is locally common in summer on both sides of the peninsula (81, 85), it becomes even more local southward, with a breeding limit apparently close to the county line in northern Northampton County (85). The populations in southwestern Maine (from South Thomaston) to northeastern Massachusetts (Plum Island) overlap the southern Atlantic coastal distribution of Nelson’s Sparrow, and constitute a zone of hybridization and introgression (68; see Systematics: Related Species).

We find no conclusive evidence of breeding, now or in the past, in the coastal marshes of northeastern North Carolina. The southern limit of breeding claimed for Pea Island, North Carolina (south of Nags Head), in the American Ornithologists’ Union (AOU) Check-list of North American Birds (56, 86, 45) was based on a putative record by P. Bartsch (44) of a juvenile taken there on 2 July 1938. Wetmore (43) examined the specimen and noted that it proved to be a misidentified Seaside Sparrow. Others have looked for breeding evidence from the species’ type locality in North Carolina (42) and from Pea Island with negative results (87, 27, 77; E. S. Brinkley, personal communication). Wetmore (43) also questioned whether the Saltmarsh Sparrow breeds that far south. Thus, the southern limit of breeding for the Saltmarsh Sparrow should revert to Virginia as given in the fourth edition of the AOU Check-list (55; see above).

Overwintering Range

The overwintering range is fragmented and restricted to tidally-influenced, herbaceous wetlands from Maryland and Virginia (Delmarva Peninsula) south to Florida (47, 88). The core wintering range chiefly South Carolina south to northeastern Florida, with significant numbers, especially in mild winters (sharp-tailed sparrows disappeared in a severe winter; 89), wintering northward in coastal North Carolina (47) and Virginia (81, 88). In Delaware, few birds are reported after late December (90). North of this range, early winter numbers are irregular, vary annually, in Cape May and Cumberland counties, New Jersey (91, 92), and become increasingly irregular northward to Long Island Sound where a few birds sometimes occur in late December (Christmas Bird Counts), and once several overwintered in a mild season in the late 1970s on a south-shore marsh on Long Island (WP). Most or all are gone by January on Long Island (JSG). On Cape Cod and along the coast of Connecticut, individuals are rarely found into early winter, but the few that may occur evidently disappear when marshes ice-over (93; CSE). Rarely, there are reports in mid winter (January–March) of 1–2 individuals in coastal marshes north to Massachusetts, but reports are largely unsupported and only rarely verifiable north of Stone Harbor, New Jersey (S. Gallick, 4 February 2014).

In Florida, the species is local south of Nassau and Duval counties and along the upper Gulf coast of the peninsula. In this region, it occurs in relatively small numbers to Volusia and Brevard counties on the northeast Atlantic side, in unknown numbers in the coastal prairie in Everglades National Park, and in small numbers from the central Gulf coast (southern Pinellas County) north to Wakulla County (94, 47, 95).

Distribution Outside the Americas

No records.

Nature of Migration

Migration nocturnal mostly along coast. Depending on population or mildness of winter, most or all individuals throughout the species’ breeding range migrate. Information on primary wintering range and migration routes is based on specimen evaluation (47), regional avifaunal summaries, and limited band encounter data on the species from the U.S. Geological Survey Bird Banding Laboratory (Table 1; 26), and recent (2014–2016) use of nanotags in combination with automated receiver towers (U.S. Fish and Wildlife Service, unpublished data).

Timing and Routes of Migration

Latest sightings from states in the overwintering range represent apparent departure times of individuals from those regions. In Florida, most are gone by mid April (96), but departures are likely underway beginning in March (based on seasonal reports since 2000 in Florida Field Naturalist), when numbers drop off by 72% compared to monthly December–February reports. Latest known Florida sighting is 11 April and 27 April in Georgia. The Georgia date perhaps represents a lingering bird, while 17 May for South Carolina is almost certainly a lingering individual (47). In North Carolina, species begin to depart in March and may be gone by the end of that month, although a few birds are present into April in some years (97). Timing of spring departure of few wintering individuals from Virginia north to New Jersey poorly known, but one “extreme” date provided by Stewart and Robbins (98) as 3 June in Maryland. In western shore marshes of Chesapeake Bay in Virginia, where the species formerly bred, recent fieldwork indicated that nearly all individuals had left by 10 June (81).

Arrival on breeding grounds from southern end of breeding range northward generally occurs from mid to late April through late May. Few details are available on arrival schedule in south end of breeding range. Arrivals in Delaware and New Jersey apparently are similar in timing to New York populations (99, 90, 92), but in Cape May, New Jersey, late winter numbers exhibit an increase beginning in mid April, with another pulse in late April (100). In coastal New York, arrivals vary by age and sex, with older males first appearing in late April, but occasionally in a cold, delayed spring not until end of first week in May. Overall, main influx of older males is in first week of May. First adult females as early as 1 May, but usually not until end of first week. Most younger males and most females appear during main arrival wave in mid to late May (JSG, unpublished data). Arrival times in southern New England similar to those in New York, with males averaging earlier arrival than females in Connecticut and with numbers increasing rapidly, suggesting a more compressed arrival period than farther south (101). Birds are mostly present on breeding marshes in Massachusetts by mid May (102). On Cape Cod, earliest arrival given as 9 May (1937), while main arrival period 23 May–1 June (93). In coastal Maine, Saltmarsh Sparrows usually arrive during last 10 days of May, with early first sightings from 21 and 22 May, while a 10 May bird was an apparent early outlier (P. D. Vickery, personal communication).

Fall migration more prolonged than spring migration. However, timing of earliest migratory departures from breeding grounds is unclear and may be cryptic if birds leave individually. Assertions of departures beginning by early September in northern New England (e.g., 93) unsupported by available information. However, earliest encountered individuals in salt marshes in South Carolina appear in late September; earliest arrival (specimen) was on 8 September. Among 138 specimens taken by A. T. Wayne, earliest was on 19 September (1917), while majority arrived in second half of October (34% of 85 autumn specimens) (WP). Preliminary evidence from adults fitted with nanotags suggests that most depart New England in mid October (B. Benvenuti, unpublished data), which coincides with the end of the prebasic molt (101). In Connecticut, average departure of males is earlier than for females possibly because males initiate molt earlier (101; see also Appearance: Molt). Limited data also suggest that juveniles in their first fall may depart later than adults, although sample sizes are currently small (B. Benvenuti, unpublished data). Fall maxima from Maine to New York occur from late September to mid October (102, 103; P. D. Vickery, personal communication; JSG, unpublished data). Smaller numbers present during late October into November. First fall arrivals on wintering grounds from North Carolina to Florida vary from late September to 10 October (47, 97). Near Charleston, South Carolina, during 1999–2005, the earliest confirmed winter resident arrived on 30 September. Median arrival date of 43 wintering birds was 5 November; 90% had arrived by 15 November, the latest resident arrived 18 November (WP, unpublished data).

Previously, based on occurrence of almost exclusive tidal marsh stopovers (with only rare exceptions), migration routes assumed mostly to be over Atlantic coastal plain. Birds fitted with nanotags north of Boston appear to fly overland, rather than following the coast around Cape Cod; tagged individuals are detected in Rhode Island, but not at receiver towers out on the Cape (B. Benvenuti, unpublished data; CSE). Similarly, Saltmarsh Sparrows apparently reach wintering grounds on the Gulf of Mexico by flying over northern, peninsular Florida, but no direct evidence for this exists. Saltmarsh Sparrow casualties are very rare under TV towers. None were found in major reports from northern Florida (104, 105; specimens examined by JSG). One Saltmarsh Sparrow was a TV tower casualty about 70 km inland from the ocean in Bladen County, North Carolina (47; see general report by 106; specimen examined by JSG). Two inland specimens in the Charleston Museum (identified as A. c. diversa, WP) were salvaged under TV towers, one near Savannah, Georgia, on 4 September, and another near Charleston on 7 September. A single extralimital, phenotypic Saltmarsh Sparrow was discovered on 5 April 2002 on Cape Sable Island, Shelburne Co., Nova Scotia, where it may have wintered with several Nelson’s Sparrows and a single Seaside Sparrow (107). Two exceptional (vagrant) inland records (3 October specimen, Westmoreland County, western Pennsylvania [108], and 11–13 November photographs, Northampton County, eastern Pennsylvania [D. DeReamus, personal communication]) have come to our attention, during fall migration. A spring bird found dead in Willimantic, Connecticut on 12 June 1973, was mummified and assumed to have been carried by a vehicle from possibly suitable, inland marshy habitat that existed nearby (109). A deep inland specimen bearing a Michigan locality tag is likely a curatorial error, either secondarily mislabeled or a loose label misapplied to a specimen (110, 111).

Migratory Behavior

A nocturnal migrant. Returning birds were found on breeding marshes early in the morning that were not present the day before (77; JSG in New York). Historical and recent information on individuals (n = 6) banded in New England (U.S. Geological Survey, Bird Banding Laboratory data; Table 1) documented winter encounters from Maine to Florida (greatest travel distance, southwestern Maine to northeastern Florida). Birds banded in Virginia and South Carolina (n = 6) during winter were encountered on breeding grounds in southern New England. These last data evidently contain several recent individuals banded by the SHARP research team and collaborators, which documented 14 long-distance encounters of Saltmarsh Sparrow that had moved between their breeding grounds from New Jersey to Maine and wintering sites from North Carolina to Florida (26). Nine individuals banded or encountered along a 150 km section of coast in South Carolina represented breeding sites from New Jersey to New Hampshire (about 600 km of coast), indicating weak migratory connectivity between breeding and wintering locations. Longest encounter distance spanned about 2,000 km of coastline, including an assumed cross-peninsular flight from Atlantic to Gulf coast of Florida, from a known wintering site to a known breeding site. This last event involved a female that was banded in October 2015 on a remnant Spartina alterniflora (Smooth Cordgrass) marsh in Pinellas County, Florida, and subsequently captured at a nest in Bristol County, Rhode Island in June 2016 (L. Deaner, D. Robinson, respectively, personal communication). No evidence of sex ratio or body size segregation by latitude on wintering grounds (26).

Control and Physiology of Migration

No known studies.

Habitat in Breeding Range

Saltmarsh Sparrow is restricted to tidal salt marshes throughout its annual cycle. On its breeding grounds, it typically nests in drier, meadow-like, supratidal sections (e.g., 91, 10, 112, 113, 114) that are least likely to flood except during some high spring tides (115, 116, 117). Although the species is described as a “short-grass [salt] meadow specialist” (30), it exhibits significant opportunism and flexibility in using several graminoid patch types and special marsh features for foraging (ditches, edges of marsh pools) or nesting within and among salt marshes (e.g., 115, 118). This is reflected in their relative abundance in both low and high salt marsh settings (119, 120, 121). Most coastal marshes in the northeastern United States are altered hydrologically by ditching, which is designed to dry out surface pools and control mosquito populations (122, 123). Ditched marshes are chiefly covered by high marsh vegetation dominated by Spartina patens (Saltmeadow Cordgrass), which forms a low, dense, meadow-like thatch, and by Distichlis spicata (Saltgrass) and Juncus gerardii (Saltmeadow Rush) along the landward fringes and other higher elevation parts of the marsh. Apart from occurring widely in this vegetation zone throughout its breeding range (10, 124, 125), Saltmarsh Sparrows in some areas (e.g., in Maryland, New York, southern New England) also use unaltered low marsh where they often nest in S. alterniflora of intermediate height (ca. 0.4–1 m) in the upper intertidal (98, 126, 115; JSG). In Rhode Island, and perhaps in other areas where Phragmites is disturbed (CSE), they nest in an altered, tidally-restricted marsh in open ecotonal stands of short Phragmites where S. patens is the prevalent ground cover (115). On Long Island, individuals nested in very small, remnant patches of S. patens between the main marsh and dune scrub, behind the broad Phragmites zone (JSG). In the southern portion of their range and in southern New England, they occur locally in salt marshes where J. gerardii is prevalent in the higher elevation portions of marsh where flooding risk is lowest (98, 127, 128). J. gerardii and S. alterniflora provided greater vegetative cover on home ranges of Saltmarsh Sparrows in Maine than was available at random sites, while S. patens was less represented on their home ranges than at random sites. Thinly vegetated salt pannes also were often present on their home ranges in Maine, but they are used only in foraging (129: JSG). Birds use dense Phragmites stands or dune scrub vegetation to seek cover if disturbed when patches are nearby (JSG, CSE).

Birds of many species during settlement may respond differently in a hierarchical fashion at different scales to multiple cues associated with appropriate habitats (130). Early information on this process in the Saltmarsh Sparrow appears to support this view (39, 131), but experimental evidence indicates that settlement decisions are not influenced by conspecific social cues (40) (see Sounds and Vocal Behavior: Social Context and Presumed Function of Songs). Marsh floristics are important for nest patch selection, with birds generally found in areas dominated by S. patens, but apparently using additional cues (e.g., presence of J. gerardii) to identify suitable nest sites. At the marsh scale, bird densities (indicative of where individuals are most detected) are not necessarily correlated with areas where most nesting occurs. Another aspect of habitat selection in these sparrows is contradictory. In Connecticut, sparrow breeding density (30) and presence (125) were positively related to marsh area at a landscape scale. Although the relationship was not strong, breeding density increased with greater marsh size even though sparrows also occupied some of the smallest marshes in the region (30). In contrast, Shriver et al. (132) found no such relationship in a range-wide analysis that included Connecticut, perhaps because sparrows in the northern portion of the species’ range respond differently to marsh size variation than those in southern New England. The latter study also used occurrence or presence in marshes (rather than density) as the response variable in their analysis, which may account for some of the difference. Moreover, variation in responses to habitat patch size is not unusual in bird studies, and might arise from sampling differences among studies (133).

Recent modeling work in New England seeks to establish relationships between habitat features and sparrow numbers and productivity (116, 39, 118). Model selection affirmed that adult numbers of both sexes were positively associated with distance from upland edges, with deep layers of persistent thatch, and in males with more uniform graminoid vegetation in saltmeadow areas. However, different factors evidently influence where females place nests (see above; for detail, see Breeding: Nest) relative to how adults use marshes for other routine activities. Wide presence of males and females on marshes reflect broad use of different microhabitat patches for foraging (JSG unpublished data; see Diet and Foraging: Microhabitat for Foraging). Males also use marshes widely as they seek sexually receptive females away from their nests (134). Thus, the perceived issue (39: 615) of why these sparrows use areas different from those where most females nest is easy to understand. Also, the observation that counts of sparrows do not correlate with nest density (39) makes sense from this perspective.

Adult females and some fledglings carrying a transmitter during the post-fledging period exhibited an overall pattern of habitat use different from that reported for other stages in their life cycle (135). In Connecticut, 75% of females were located closer to marsh edge than random areas available. Other females used mostly tall S. alterniflora with patches of bare mud (exposed during neap tides), where, in both cases, apparently foraging is facilitated and good cover for security is available in situ or close by.

Habitat in Migration

Little information on habitats used during migration, but stopovers are in coastal salt marshes. From all that is known, species is a near-obligate Spartina inhabitant in tidal-marshes during its entire life cycle, except on rare vagrancy occasions inland when it seeks marshy, freshwater wetlands (see above). Use of this general habitat type, and associated drier zones of Distichlis and low-growing Juncus species, during migration is to be expected. Rarely occurs out-of-habitat in unusual surroundings: an individual originally banded at Chapman’s Landing, New Hampshire, was photographed on a sandy Atlantic beach where it foraged around a pier at Coney Island, New York (see photos here; SHARP, unpublished data).

Habitat in the Overwintering Range

Historical sources on regional avifauna are almost mute on the subject of habitat use in the overwintering range. Most simply mention “salt marshes.” In Florida, Saltmarsh Sparrow chiefly occupy the “drier portions, among dense and matted growth of Spartina and other marsh grasses” (136). On the central Gulf of Mexico coast of Florida, which once had significant numbers of overwintering Saltmarsh Sparrow (47), historically it was found in “short-grass tidal marshes,” evidently signifying Spartina rather than tall Juncus roemerianus (Black Needlerush) (Fargo 1926). Along the Florida Gulf coast, Saltmarsh Sparrow will even use small patches of salt marsh with remnant areas of S. alterniflora (L. Deaner, unpublished data; JSG), while it mostly avoids large monocultures of J. roemerianus (95). Sharp-tailed sparrows (both species) primarily occupied S. alterniflora, and associated Distichlis and Salicornia, along the Gulf Coast in Levy County, Florida, but in a large community of these birds, only 4% were Saltmarsh Sparrow (94). High spring tides often force migrant or overwintering sparrows out of wetter sections of tidal marshes into landward edges, including drier grass zones, spoil banks, and dune scrub (137, 97).

Historical Changes to the Distribution

Range contraction is evident at the southern end of its distribution in Virginia and Maryland around Chesapeake Bay (82, 83), and locally elsewhere. This sparrow has suffered habitat restriction from local extirpation due to habitat degradation and loss in most of its range (e.g., 36, 74) and has experienced strong declines since at least the 1990s (74). See also Conservation and Management.

Bailey (138) reported the Saltmarsh Sparrow to be an abundant breeder in salt marshes of the western shores of lower Chesapeake Bay in Virginia, in the early 1900s. Even by the late 1950s, it was breeding in Maryland tidewater areas on both sides of the upper Chesapeake Bay north to Queen Anne’s County (Eastern Shore) and Anne Arundel County (Western Shore) (98). By the 1980s, Breeding Bird Atlas results in Maryland (1983–1987) suggested that the species was absent from the Western Shore and was confirmed breeding on the Eastern Shore north only to Dorchester County (but 2 probable outliers were still farther north in Talbot County) (82). The second Breeding Bird Atlas in Maryland (2002–2006) failed to locate Saltmarsh Sparrow on the eastern side of Assateague Bay where the species had occurred during the first period of atlasing (83), and no birds were reported in Talbot County. Recently, further survey work in Virginia documented current distribution on the southern Delmarva Peninsula and a single, remnant summer occurrence on the southwestern side of the bay (84, 85).

Range expansion may have occurred at the north end of the species’ range in southwestern Maine. This change is inferred from available historical data, but it may only reflect inadequate early survey work in the region on marshes north of Popham Beach, Sagadahoc County, a taxonomic history that discouraged distinguishing Saltmarsh Sparrow from its sister taxon (Nelson’s Sparrow), or prevailing confusion and misinformation on its species-specific song (49, 64). However, Norton (61, 139), as an early reviser of the single species then recognized, was especially interested in the distribution of Saltmarsh Sparrows and “Acadian” sparrows (now the maritime subspecies of Nelson’s Sparrow) in Maine. He reported the former was breeding only as far north as Scarborough, Cumberland County, while the latter occurred south in summer to Popham Beach, Sagadahoc County, south and north of Portland, respectively. Montagna (70, 27) and Palmer (71) essentially confirmed this view, except the latter location also was known as an intergrade site between the 2 taxa, and a putative Saltmarsh Sparrow specimen was taken there at that time. There is no evidence that either Montagna or Palmer searched marshes north of Popham Beach for A. c. caudacuta. The tidal marsh survey undertaken on the coast of Maine by Hodgman et al. (64) established the large marsh on the Weskeag River in South Thomaston as the northern limit of breeding in the species. Subsequent genetic sampling along a transect throughout Maine also identified this as the northernmost site for pure Saltmarsh Sparrows (68). North of that, tidewater marshes are mostly absent on the central coast and those that are present are quite small, and have little Spartina (64).

Fossil History

No records.

Recommended Citation

Greenlaw, J. S., C. S. Elphick, W. Post, and J. D. Rising (2018). Saltmarsh Sparrow (Ammospiza caudacuta), version 2.1. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.sstspa.02.1