Seaside Sparrow Ammospiza maritima Scientific name definitions

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



Walking, Running, Hopping, Climbing, etc.

Walking and running are typical modes of movement on ground. Walks (wades) in water. Hops when crossing rough surfaces or moving between stems. Climbs or clambers in herbaceous vegetation.


Long-distance flight is direct and strong, with slight hesitancy in wingbeat tempo that gives path noticeably irregular or jerky aspect (JSG). The “Locality” flight (a brief, localized flight just above vegetation, typically by female) near nest is distinctly jerky, with posterior body pumping through up-down arc; this flight appears to express strong hesitancy about being exposed (JSG). During intense circling chase, flight is rapid and level with regular wingbeat tempo. Wingbeat also is rapid and regular during ascent of flight (song) display, but at apogee of display, wings set slightly above horizontal, and bird briefly glides diagonally downward uttering one or more Primary Songs (JSG). Flight of juvenile sparrows has characteristic hesitant quality, usually followed by clumsy dive into grass (2).


Preening, Head-Scratching, Stretching, Bathing, Anting

Males spend about 0.8% of the day preening. Another 0.9% of the day is spent alternating short bouts of preening and singing (37). Preening is often performed on an exposed perch, especially in early morning when the grass is wet. Adults occasionally give tuck calls when preening. Periodically, rectrices are fanned and wagged vigorously back and forth. Head scratch is indirect (leg over extended wing) (7); direct head-scratching has also been reported (175). Stretching involves unilateral and bilateral maneuvers; in unilateral stretch, wing and leg of same side extended and tail partly fanned and flexed toward that side. Unilateral stretch may be repeated on contralateral side; often this followed by bilateral stretch, with both partly folded wings lifted above back as bird flexes each leg (175, JSG). Birds frequently yawn and bill-wipe.

Adults and juveniles mandibulate orifice of uropygial gland and apply secretion by running bill over rectrices and by jabbing body plumage (see Figure 8). Adult seen bathing in shallow water on edge of tidal creek repeatedly submerged ventral surface, and dipped head, then stood up, shook head and fluttered spread wings. Bill is cleared of mud or debris by wiping against stems or leaves and by head-shaking. Anting probably does not occur (e.g., in Texas, an ant that crawled over juvenile's wing for extended period was ignored [M. Bartosik, personal communication]). Dust-bathing not reported.

Sleeping, Roosting, Sunbathing

Juveniles seen sunbathing during preening bouts: bird exposes dorsum to sun while spreading tail, drooping and fanning wings (M. Bartosik, personal communication). Little information on sleeping and roosting. Female spends night in nest while incubating and brooding. Postbreeding adults in late summer roost in tall cordgrass stands on outer marsh (WP). During extreme high tides, birds congregate in secondary (diurnal) roosts in tall vegetation growing at higher elevation, such as needlerush (Juncus roemerianus) and Phragmites.

Daily Time Budget

In breeding season in New York, males apportion daylight period as follows: foraging, 61.0% of total time; singing, 20.7%; miscellaneous activities (body maintenance, flight, intersexual interactions, predator avoidance), 6.1%; resting, 4.9%; nest attendance, 4.0%; intrasexual aggression, 3.7% (116). Most foraging is concentrated in afternoon (1300–1600 h), at which time males may spend 60–70% of time foraging (37). Percentage of time that males spend foraging increases after young hatch (from 53.0% to 77.3%), accompanied by reduction in time spent singing (from 29.2% to 3.8%). Besides spending more time in nest attendance, the other major activities of males do not vary significantly over breeding season. Males nesting in ditched marshes had same activity budgets as nearby males in unaltered marshes, although former had home ranges about 7 times larger (116). No information on female time budget.

Agonistic Behavior

Physical Interactions

Breast-to-breast fight occurs during territorial disputes between males. Two opposing males rise in air, clawing or pecking at each other's breast. One bird sometimes grips other on ground and holds it down, both birds giving zuck calls. On one occasion, two males fell into water locked together and remained submerged for several seconds, then flew out in prolonged chase, during which they gave more zuck calls (169). On feeding sites in Texas, juveniles also engaged in breast-to-breast fight (M. Bartosik, personal communication). Male–male chase has been seen in all study populations. These may be prolonged, as in one case where persistent intruder chased or was chased by territory owner for > 1 min (7). Territorial adult males may chase juveniles that enter their territories (161). Outside fighting context, pecking of opponent is not often seen in field. In captive group, pecking was common and usually preceded by head-forward threat (169).

Communicative Interactions

Wings are frequently raised during border disputes, often while bird gives tchi call or sings (Wing-raise of Post and Greenlaw [169]). Both juveniles and adults wing-raise during nonbreeding period. One or both wings held up, occasionally asymmetrically, usually 30–45° above horizontal. Wings vibrated, tail spread, body feathers fluffed. Raising wings reveals yellow marginal coverts at the wrist (M. Bartosik, personal communication).

Disputing individuals, both adult and juvenile, may raise and lower bodies in bobbing pattern, with heads held down or horizontally. Birds often gape, fluff plumage, and droop wings (169, 7). May give head-forward threat and jab at each other.

During border disputes, male may pull vegetation (redirected attack) and sometimes pick up grass or wrack. In one case, male carried piece of grass about 10-cm long for several minutes while in presence of opponent. On foraging sites in Texas, juveniles apparently displayed to each other by carrying debris or feathers (as long as 10 cm); such individuals also assumed erect postures (M. Bartosik, personal communication). Carrying material was occasionally followed by a chase. Two or more disputing birds, including juveniles, may engage in sham-foraging for > 1 min (169), a synonym for "displacement feeding" in an agonistic context (178), during which two males walk paralleling one another, each about 20–30 cm apart, pecking at the substrate, but apparently not capturing prey.

Wing-tail flicking occurs in social situations: wings moved rapidly over back, then down and out from body; simultaneously, tail is moved up and down. This is evidently preflight (flee) signal. Tsip call is usually associated with wing-tail flicking.

Bill-wiping and sham-preening occur during aggressive interactions and probably represent displacement activities. One apparent appeasement display, hunch-down (169), in which subordinate individual pulls head in, raises crown feathers, and ruffles feathers, is commonly seen in captives but only rarely in wild, perhaps because giver is usually hiding in vegetation.

Territorial Behavior

Uneven dispersion of breeding pairs over apparently homogeneous habitat led to description of the Seaside Sparrow as colonial or semi-colonial (e.g., 179, 180, 161, 48). Clusters of territories, however, may simply reflect common response to heterogeneity of habitat (151, 116, 115, 3, 181). Audubon (151) stated that “many nests may be found in the space of few acres of these marshes, where the land is most elevated… They select these spots, because they are not liable to be overflowed by high floods….” Within suitable microhabitats, nests regularly spaced. There is no evidence that female locates nest at center of male's territory; indeed, nests are occasionally built at edge of territory (182). Mean distance to nearest-neighbor nest in New York was 46.4 m ± 17.6 SD (n = 184).

Northern birds breeding in unaltered marshes have smaller territories than those in structurally equivalent southern marshes. Territories in coastal, unaltered salt marshes are smaller than those in ditched or inland marshes. Because suitable nesting and feeding sites often occur in separate areas, birds may leave territory to forage, leading to “grouped territories” (116). Males in New York spent up to 42% of time foraging outside activity space surrounding nest (116). Separate foraging areas usually not defended (53, 116), but see DeRagon (176). In some areas males defend apparently separate feeding areas, but these may be connected to nesting areas by little-used, but defended, corridors (2).

Mean territory size: Buzzard's Bay, Massachusetts: 3,953 m2 (range 1,290–10,423, n = 17) (117); Narragansett Bay, Rhode Island: 4,545 m2 (range 944–8,837, n = 18) (176); Oak Beach, New York: 1,203 m2 (range 160–6,190, n = 25) (169); Tobay, New York: 8,781 m2 (range 810–17,640, n = 13) (116); Gulf Hammock, Florida: 1,600 m2 (range 200–3,200, n = 37) (3); Taylor Slough, Florida: 15,000 m2 (range 3,000–66,000, n = 43) (161); Ochopee, Florida: 36,000 m2 (range 7,000–8,000, n = 10) (7); St. Johns, Florida: 5,100 m2 (range 1,600–10,060, n = 14) (183).

Territory quality (relative nesting, food, and cover/protection) values vary widely within same population. At Oak Beach, New York, 36% of territories had total qualities that exceeded that of lowest-quality territory by at least 3 fold. Comparable figure at Gulf Hammock, Florida, was 50%. Maximum differentials in total relative quality of territories were 10.1 in New York and 5.8 in Florida (182).

Most territory boundary disputes were settled by April (Florida) or mid-May (New York). Thereafter, territory owner usually reacts to intruder by increased singing, then with visual displays, but seldom with physical attack. Switch from song to visual displays usually occurs when birds < 5 m apart (173).

Southern (resident) birds stay in or near territories in winter, but extent of territory defense is unknown. An exception to this behavior occurs (at least) in South Carolina in nonbreeding populations in coastal marshes near Charleston that move several miles up rivers inland to brackish marshes where they breed only to return to the coast during July (125) (WP); see Movements and Migration: Migration Overview).

Captive birds formed linear dominance hierarchies with occasional reversals. Body size possibly influences position in hierarchy, but sex evidently does not (WP). Little information on dominance relations in wild; in nest vicinity, females dominant to mates (WP, JSG).

Sexual Behavior

Mating System and Sex Ratio

Socially monogamous throughout range; no cases of natural polygyny known, although male can be induced to accept more than one mate (182). In dense breeding population in New York, all 225 marked males observed (1970, 1977–1980) were apparently mated. In a ditched marsh in New York with low population density, only 4 of 10 males were mated in 1970. At Gulf Hammock, Florida, bachelor males varied in frequency from 11% to 23% of territorial males in different parts of study area in 1980 (182). Variation in incidence of unmated males between populations is related to habitat suitability (3, 182). Females checked regularly (83 in New York, 61 in Florida) remained with original mates through breeding season. After nest failure, female moved nearby in same territory and renested. Territory quality (suitable cover, nest sites, and food) is very heterogeneous within groups. However, the “polygyny threshold” is evidently not exceeded either because resources on salt marsh are not limiting (cover, nest sites) or because females can nullify effects of food disparity between territories by foraging outside males' territories (182). In nonmigratory populations, pairs may associate throughout year in or near breeding area (WP).

At Oak Beach, New York, when territorial males were removed (n = 33), adjacent males enlarged own territories and collectively occupied all or most of vacant area. Widowed females attending nests were included in part of enlarged territory of neighboring males (182). No male acquired > 1 additional mate in this way. In aggregate, removal experiments suggest no floating reserve of nonbreeding males in New York populations (182). At Gulf Hammock, Florida, experimentally muted males often lost territories to floaters (birds that had territories previous year, but not year of study) (173). Also in Florida, 5 of 9 males experimentally implanted with testosterone in a pilot study obtained an additional mate, an effect attributed to increased singing rate induced by hormone (184).

Females aggressive during breeding season. Aggression is nest-centered; its role in maintenance of monogamy not clear (182). Of 199 overt agonistic encounters (supplanting, chasing, attacking) at Oak Beach, New York, 34% involved a female, and all but one of these concerned aggression toward intruding male approaching a nest. Females not seen chasing each other, though they chase male Seaside Sparrow and male Saltmarsh Sparrow (Ammospiza caudacuta). Evidently "polygyny thresholds" are not limiting, at least in rich marsh habitat in New York, perhaps also because females can nullify differences in habitat quality by feeding at distant sites outside nest-centered territories. These factors may account for the maintenance of social monogamy in the Seaside Sparrow (182).

No data on primary sex ratios (sex ratio at fertilization). Sex ratio of 79 juveniles (secondary ratio) collected late in breeding season in New York was 0.76 male: 1.0 female, not significantly different from 1:1 (163). Adult sex ratio (tertiary sex ratio) about equal at Oak Beach, New York (WP).

Courtship, Copulation, and Pair Bond

Pair bond apparently established immediately after female arrives on male's activity space. Characteristics that female uses as criteria for mate choice (if any) are not known. Male follows female closely on ground and in air, frequently raises wings, sings, and gives whinny and tchi calls. Female also gives whinny and tchi calls. Just before copulation, female fluffs body feathers and raises wings to horizontal, where they are quivered. Tail is raised and spread, and beak is pointed upward. Female frequently whinnies, and as male approaches more closely, or moves to her back, she utters seep call. Coition lasts < 3 s. Male crouches on back of female, sometimes gripping her nape with his beak, while his wings are extended horizontally and quivered slightly. Copulation may be repeated up to 3 times within 5 min. After coition, female may give songlike vocalization, and begins gathering nest material, which she takes to nest site, often while uttering whinny. Male after coition may gather grass, which he may carry short distance before dropping; male not seen adding grass to nest (169).

Mate-guarding by male is tied to territory defense in New York. Males were not seen defending or following females that leave territory. Mates usually remained together through breeding season. If nest failed, female built next nest in new spot in mate's territory. Female repulses advances of intruder males, often wing-raising and giving agonistic vocalizations (tchi and tuck), which attract territorial male. However, on the northern Gulf coast of Mississippi (Jackson County), males reportedly did not aggressively mate-guard their mates although they often did follow them closely during their nest-building activities (11).

There is little information on mate fidelity between years. Evidently, females returning in spring may or may not mate with previous mate, perhaps depending on nest-site quality of male territories, which varies annually (116). In nonmigratory populations, pair bond apparently maintained through year, as female stays in or around male's territory (WP). Extent of male territory defense in winter is not known. Males respond to tape recording of song as early as 23 February in northern Florida (WP).

Extra-Pair Mating Behavior/Paternity

On John's Island, South Carolina, where 60 pairs nested on an 8-ha study site, about 11% (95% CI: 4–22%) of 47 nestlings from 3 of 18 broods (about 17% of broods) were sired by an extra-pair (EPP) male (185). On the northern Gulf coast of Mississippi, 30 of 194 nestlings (16%) were sired by EPP males, and 20 of 63 broods (32%) contained at least one EPP chick (11). Of 11 species of Passerellidae for which EPP rates of broods are known (186, 187, 188), only Field Sparrow (Spizella pusilla) had a lower rate than Seaside Sparrow (185, 11).

Brood Parasitism of Conspecifics

Not reported.

Brood Parasitism of Other Species

Not reported.

Social and Interspecific Behavior

Degree of Sociality

In New York, fledglings and juveniles gathered in loose groups of up to 15, usually centered around sheltered feeding areas. Flocks were integrated to extent that individuals follow each other between sites. One or more adults, as well as Saltmarsh Sparrow, may join groups. Seep note (169) is given by perched and flying flock members. Flocking also seen in New Jersey (2), South Carolina (WP), and Florida (161, WP).


In southern Texas, juveniles, while alone or in each other's presence, carried materials such as leaveshars or feathers; also picked up, mandibulated, and dropped the same non-food objects repeatedly. Considerable time was expended in dislodging attached objects such as half-buried stones, and in breaking off tips of wire barbs or wooden nubs of fence posts. Subsong, frequently given by juvenile males (see Sounds and Vocal Behavior), possibly represents acoustic play (189).

Nonpredatory Interspecific Interactions

New York males consistently supplanted and chased Saltmarsh Sparrow that landed in their territories: 66% of Seaside Sparrow agonistic interactions involved Saltmarsh Sparrow (n = 1,111 interactions, 1977–1978) (JSG, WP). Both sexes chased Saltmarsh Sparrow away from nest vicinities. Many interactions with Saltmarsh Sparrow simply involved supplants (from frequently used song posts), whereas chases tended to be short and seemingly perfunctory, unlike many, more vigorous, intraspecific male–male chases (JSG), suggesting that males did not misidentify Saltmarsh Sparrow (i.e., the "mistaken identity" hypothesis of Murray [190, 191]). At Oak Beach, New York, which has about same numbers of each species, average interspecific nearest-neighbor nest distance for Seaside Sparrow and Saltmarsh Sparrow was 46.4 m ± 32.6 SD (n = 184); corresponding intraspecific distance of Seaside Sparrow nests was 32.6 m ± 17.6 SD (n = 184) (WP, JSG). Seaside Sparrow uses about 5 visual displays and 5 vocalizations during aggressive encounters with Saltmarsh Sparrow (169). Seaside Sparrow supplanted latter on non-defended feeding grounds in breeding season and in mixed-species flocks in winter (WP, JSG). In southern Texas during nonbreeding period, both adults and juveniles chased Marsh Wren (Cistothorus palustris) and Sedge Wren (Cistothorus stellaris) in vegetation, and also Least Sandpiper (Calidris minutilla) that attempted to feed on mudflats near them (M. Bartosik, personal communication).

In captivity, Seaside Sparrow and Saltmarsh Sparrow were aggressive to each other; of 166 interspecific interactions (supplants, chases, attacks) in a captive flock of 11 Seaside Sparrows and 7 Saltmarsh Sparrows, 85% were won by Seaside Sparrow. No clear-cut hierarchy existed among individuals of both species. Captive male Saltmarsh Sparrows mounted male and female Seaside Sparrows 16 times during a 21-hour observation. Captive male Seaside Sparrow did not mount Saltmarsh Sparrow, although they occasionally mounted other Seaside Sparrow (WP). When forced by winter high tides to congregate on a small island, Seaside Sparrow came in contact with sharp-tailed sparrows (192).

In field, Montagna (86) collected male Saltmarsh Sparrow and female Seaside Sparrow while they were copulating. Griscom (in Hill [193]) saw a male Seaside Sparrow attempting to copulate with a female Saltmarsh Sparrow. Hybrid Seaside Sparrow × Saltmarsh Sparrow have been collected (85).

Seaside Sparrow also chases Marsh Wren from nest vicinity and are chased by male and female Red-winged Blackbird (Agelaius phoeniceus). On Long Island, New York, meadow vole (Microtus pensylvanicus) uses abandoned Seaside Sparrownests, but there is no evidence that voles evict sparrows. On Chesapeake Bay, Maryland, Seaside Sparrow and Song Sparrow (Melospiza melodia) nested near each other on small spoil islands but did not interact (194).


Kinds of Predators

Few predators appear to take adults in breeding season, but in New York, several nests depredated by rats resulted in death of females on nest at night or early morning near Phragmites edge (WP, JSG). A young Seaside Sparrow was found in the nest of a White-tailed Hawk (Geranoaetus albicaudatus) (195). Two Cape Sable Seaside Sparrows (A. m. mirabilis) were found in the nest of a Short-tailed Hawk (Buteo brachyurus) (196).

In northeastern United States, main predators of adults are likely Northern Harrier (Circus hudsonius), American Crow (Corvus brachyrhynchos) (2), Barn Owl (Tyto alba), and Short-eared Owl (Asio flammeus). Three of 4 deaths of radio-marked A. m. mirabilis in the Florida Everglades were attributed to avian predators and one was found in the gut of a cottonmouth (Agkistrodon piscivorus) (131). In New York, known predators of nest contents are Northern Harrier, Fish Crow (Corvus ossifragus), Marsh Wren, Norway rat (Rattus norvegicus), short-tailed weasel (Mustela erminea), and garter snake (Thamnophis sirtalis) (JSG, WP). In New York, Norway rat attacked nests near Phragmites stands often at night and typically killed the adult female leaving the carcass mostly intact (JSG). Garter snake may force round entrance holes through bottom of nest or enter nest from above leaving nest tilted to one side (JSG). At Oak Beach, New York, nests closer together than average were no more likely to be depredated than those farther apart (116). In the southeastern United States, nest predators include Fish Crow, raccoon (Procyon lotor), and marsh rice rat (Oryzomys palustris), the latter frequently modified used Seaside Sparrow nests or ones that they had usurped (WP). Eastern rat snake (Pantherophis obsoletus) may rarely take nest contents. In northern Florida, nests in lower, sparser vegetation (saltgrass [Distichlis spicata], glasswort [Salicornia]) are more likely to be depredated than those in taller, denser vegetation (needlerush) (119). In the Florida Everglades, the most important predators were marsh rice rat and cottonmouth, which tend to be most active late the breeding period when conditions are wetter than earlier in the season; this resulted in typically higher nest success for first broods in A. m. mirabilis than second and third broods (197). Increased predation of A. m. mirabilis nests was related to higher water levels occurring at start of wet season, which affect predator abundance or activity. Nests started early have higher success than late-season nests (198).

In South Carolina in November, Cottam and Nelson (199) examined 21 Barn Owl pellets, finding 33 items. Each of 5 pellets had remains of a single Seaside Sparrow; only 2 other passerine species were detected. In Georgia, a fish (Fundulus heteroclitus, Mummichog) was video-recorded entering a flooded nest containing a just-hatched nestling, then drowning and feeding on it (200). The report on this apparently unusual predator may be important in this southern tidal marsh, and potentially relates to nest height relative to a predation-flooding trade-off in this population (201).

Response to Predators

Female disturbed from nest may give distraction display (151, 169), in which she makes short flights, runs on ground with wings raised, and utters tsip and tuck calls. Display appears to be elicited most often when female is actually on the nest—if the female is away when the nest is approached, her response is to mob (wing-tail flick while uttering tsip and tuck calls) from a distance. Both male and female may give distraction display when young are handled (2). In nonbreeding period, ≥ 2 birds may gather to mob terrestrial predators, by perching in top of vegetation, uttering tuck and tsip calls, while wing-tail flicking. Mobbing response can be elicited by squeaking of human or by distress call of handheld bird. Mobbing birds quickly dive into vegetation when predator moves, and do not follow predator. Marsh Wren and Saltmarsh Sparrow may join mobbing Seaside Sparrow. Birds in open take cover when nearby Red-winged Blackbird gives cheer (hawk alarm call) (202) and when Willet (Tringa semipalmata) or Black-necked Stilt (Himantopus mexicanus) utter alarm calls. On approach of Northern Harrier, birds seeks dense grass silently (2) or utters short tsip twitter before disappearing into cover, where they freeze (JSG); birds in southern Texas respond in the same way when Great-tailed Grackle (Quiscalus mexicanus) or any raptor approaches (M. Bartosik, personal communication).

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