Ammodramus maritimus

Geographic Range

Ammodramus maritimus (new taxonomic identification: Ammospiza maritima ) comprises 12 subspecies, all of which are found along the Gulf and Atlantic Coasts of the United States from Texas all the way to the southern tip of Maine, and up to 13 miles inland. Some northern subspecies migrate from Massachusetts and North Carolina to South Carolina or Georgia to breed, but many are nonmigratory.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

The habitat of seaside sparrows consists of coastal wetlands dominated by clumped halophyte plants and dense grasses. They are habitat specialists, using salt marshes as grounds for both breeding and feeding. They spend much of their time on or near the ground in these marsh grasses. Their nests are typically 6 to 12 in off the ground.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Wetlands
• marsh marsh

• Other Habitat Features
• estuarine estuarine

Physical Description

Seaside sparrows are stocky sparrows with a large, long, and pointed bill. They have long legs and a rounded tail and wings. Adults typically weigh 19 to 28 g, measure 12.95 to 14.99 cm long, and have a wingspan of 18.03 to 20 cm. The shade varies among subspecies, but overall their plumage is dark grayish brown on the dorsal side and lighter on the ventral side with some darker streaking. A yellow spot in front of the eye and a white throat with a dark band on either side characterize the species. Males and females appear the same. No information is available about the basal metabolic rate.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Development

Ammodramus maritimus shares the same oviparous development of all bird species. There is no information about deviations from this general pattern of development.

Reproduction

Ammodramus maritimus is a socially monogamous species, with males and females forming a pair-bond during the breeding season. Each female in a pair has exclusive access to her mate’s territory, which can be anywhere from 0.25 to 2.0 acres. Males establish nesting territories through song and pair with a female quickly once she enters his territory. Once paired, the female may make sex-specific vocalizations until the time she begins to lay eggs. Males defend their territory from conspecifics with warning calls, and sometimes mid-air fights involving pecking and clawing.

• Mating System
• monogamous monogamous

The breeding season for Ammodramus maritimus occurs during the dry season beginning in March and lasting through July, and their breeding interval averages 67 days across all tidal marsh populations. Their nests are built 14-28 cm above the substrate to avoid tidal flooding. The female constructs the nest out of fine grasses, forming a tight cup (2.4 in across, 2 in deep), which is often partially covered by adjacent marsh plants. A typical clutch contains approximately 3 eggs, and a female is capable of initiating as many as four clutches per season for a total of 12 eggs. Incubation typically lasts 12 days, which can start as soon as the penultimate egg has been laid. The time to fledgling is 7-10 days, and the time to independence is 33 days. The average number of fledglings produced per female per year is nine. No information is available on the mass of hatchlings or the age at which individuals reach sexual maturity.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

As socially monogamous pairs, male and female seaside sparrows share parental care. The female does all of the incubating while the male forages, but once the clutch hatches, the male helps feed the offspring so that the female can leave the nest for short periods.

• Parental Investment
• male parental care male parental care
• female parental care female parental care
• pre-fertilization
  • provisioning
  • protecting
    • male
• pre-hatching/birth
  • provisioning
    • male
  • protecting
    • male
• pre-weaning/fledging
  • provisioning
    • male
    • female
  • protecting
    • male
• pre-independence
  • provisioning
    • male
    • female

Lifespan/Longevity

The expected life span of seaside sparrows in the wild as well as captivity is 8-10 years and the longest known life span is 10 years.

Behavior

Ammodramus maritimus is solitary other than the breeding season when they pair-bond to mate. It has many different physical displays and vocalizations for both attracting a mate and defending its territory. It moves by flying through the marsh grasses or hopping on the ground to forage.

• Key Behaviors
• flies
• diurnal diurnal
• motile motile
• migratory migratory
• solitary solitary
• territorial territorial

Home Range

Ammodramus maritimus has a territory that is nest-centered and usually anywhere from 100 to 10,000 square meters, and an overall home range of 200 to 20,000 square meters. Part of this home range is undefended "activity space" that may or may not overlap with the activity space of a neighboring home range.

Communication and Perception

Seaside sparrows communicate with their mates as well as rival males. They use up to 27 different visual or vocal displays, such as raising their forehead and crown feathers or making warning calls. Their main perception channels are visual and auditory. Like many bird species, A. maritimus can see ultraviolet light.

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• ultraviolet
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Seaside sparrows are omnivores that forage seeds, leaves, and fruits of halophytic plants, in addition to hunting small invertebrates like insects, amphipods, and mollusks. They can cling to marsh grasses as they strip seeds and procure insects, search mud for invertebrates, or forage by scratching through dead vegetation with their feet.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
  • eats non-insect arthropods
  • molluscivore molluscivore
• herbivore herbivore
  • folivore folivore
  • frugivore frugivore
  • granivore granivore
• omnivore omnivore

• Animal Foods
• insects
• terrestrial non-insect arthropods
• mollusks
• aquatic crustaceans

• Plant Foods
• leaves
• seeds, grains, and nuts
• fruit

Predation

Though little research has been done to determine the species or number of predators in their nesting areas, some known predators of Ammodramus maritimus include snakes, raptors, and the rice rat, Oryzomys palustris . They stick to the dense grasses to avoid predators, only landing on the ground to forage.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

As omnivores that eat fruits and seeds, they are active seed dispersers. They themselves do not parasitize any species, but there is evidence of nest parasitism of A. maritimus by brown-headed cowbirds, Molothrus ater . Commensal and mutualistic relationships are also unstudied.

• Ecosystem Impact
• disperses seeds

Economic Importance for Humans: Positive

As specialists of their salt marsh habitat, Ammodramus maritimus are wonderful indicator species for the health of their coastal environments. Maintaining the health of these coastal ecosystems is beneficial to many human industries, such as tourism in the Florida Everglades where many Ammodramus populations call home.

• Positive Impacts
• ecotourism ecotourism

Economic Importance for Humans: Negative

There is no information available on any negative economic impacts to humans by seaside sparrows.

Conservation Status

Ammodramus maritimus , which has been reclassified as Ammospiza maritima , is currently listed as stable on the IUCN Red List of threatened species, however the subspecies Ammodramus maritimus mirabilis has been considered endangered since 1967, and the subspecies Ammodramus maritimus nigrescens went extinct in 1990. The decline of subspecies of Ammodramus has been attributed to the decline in tidal salt marsh habitats due to anthropogenic factors such as unnatural water regimes and the introduction of exotic plants. In order for these subspecies to increase in abundance, restoration or expansion of these habitats is crucial.

Additional Links

Encyclopedia of Life

Contributors

Madison Edmoundson (author), Texas State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

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Benscoter, A., S. Romañach. 2022. Endangered Cape Sable Seaside Sparrow ecology: actions towards recovery through landscape-scale ecosystem restoration. Endangered Species Research , 49: 199-215.

Cuthill, I., J. Partridge, A. Bennett, S. Church, N. Hart, S. Hunt. 2000. Ultraviolet Light in Birds. Advances in the Study of Behavior , 29: 159-214.

Davis, K., A. Settlecowski, M. Roeder, C. Enloe, T. Virzi. 2021. Range-wide population genetic analysis of Seaside Sparrow (Ammospiza maritima) supports at least five distinct population segments that do not align with current subspecies descriptions. Ornithological Applications , 123: 1-15.

Greenberg, R., J. Grenier. 2006. Terrestrial vertebates of tidal marshes: evolution, ecology, and conservation. Studies in Avian Biology , 32: 32-53.

Greenlaw, J. 1983. Mirogeographic distribution of breeding seaside sparrows on New York salt marshes. The Seaside Sparrow, Its Biology and Management , 5: 99-114.

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Lehmicke, A., C. Jones. 2014. First confirmed records of parasitism of Seaside Sparrow nests by Brown-headed Cowbirds. Southeastern Naturalist , 13.1: N1-N5.

Lockwood, J. 1997. Life history of the endangered Cape Sable Seaside Sparrow. The Wilson Bulletin , 109: 720-731.

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Cornell University. 2025. "Cornell Lab of Ornithology" (On-line). All About Birds. Accessed March 01, 2025 at https://www.allaboutbirds.org/guide/Seaside_Sparrow/lifehistory#nesting .