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Fish crow
In Red Hook, Brooklyn
Secure
Secure  (NatureServe)[2]
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Corvidae
Genus: Corvus
Species:
C. ossifragus
Binomial name
Corvus ossifragus
Wilson, 1812
Fish crow range

The fish crow (Corvus ossifragus) is a species of crow associated with wetland habitats in the eastern and southeastern United States.

Taxonomy and etymology

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The fish crow was given its binomial name by the Scottish ornithologist Alexander Wilson in 1812, in the fifth volume of his American Ornithology.[3][4] The binomial is from Latin; Corvus means "raven", while ossifragus means "bone-breaker". It is derived from os or ossis, meaning "bone", and frangere, meaning "to break".[5] The English-language common name fish crow also derives from Wilson, who ascribed the name to the crow's aquatic diet, as described to him by local fishermen. He distinguished the fish crow from John Bartram's great seaside crow by the former's diminutive size when compared to the American crow.[3]

The fish crow's taxonomic relation to other species of the Corvus genus is still poorly understood, but DNA sequencing indicates that it is most closely related to the palm crow (C. palmarum) and the Jamaican crow (C. jamaicensis), with the three species forming a Nearctic clade.[6] The Sinaloa crow (C. sinaloae) and Tamaulipas crow (C. imparatus) bear morphological similarities to and were once considered conspecific subspecies of the fish crow,[7] but have since been recognized as distinct species.[8]

Description

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In flight Cape May Point State Park, New Jersey

The fish crow is a medium-large bird, with an average adult weight of 280–320 grams (9.9–11.3 oz) in males and 247–293 grams (8.7–10.3 oz) in females.[9] The wingspan is approximately 36 inches (90 cm),[10] while the total body length is between 36–40 centimetres (14–16 in).[11]

The fish crow is superficially similar to the American crow, but is smaller and has a silkier, smoother plumage by comparison, and the bill is usually somewhat slimmer. The upperparts have a blue or blue-green sheen, while the underparts have a more greenish tint to the black. The eyes are dark brown. The differences are often only really apparent between the two species when seen side by side or when heard calling.[12]

Visual differentiation from the American crow is extremely difficult and often inaccurate.[13] Nonetheless, differences apart from size do exist. Fish crows tend to have more slender bills and feet. There may also be a small sharp hook at the end of the upper bill. Fish crows also appear as if they have shorter legs when walking. More dramatically, when calling, fish crows tend to hunch and fluff their throat feathers.

The voice is the most outwardly differing characteristic for this species and other American crow species. The call of the fish crow has been described as a nasal "ark-ark-ark" or a begging "waw-waw". Birders often distinguish the two species (in areas where their range overlaps) with the mnemonic aid "Just ask him if he is an American crow. If he says "no", he is a fish crow." referring to the fact that the most common call of the American crow is a distinct "caw caw", while that of the fish crow is a nasal "nyuh unh".[14] The fish crow also has a single call sounding like "cahrrr".[15]

Blue-green sheen visible on feathers

Distribution and habitat

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This species occurs on the eastern seaboard of the United States from Rhode Island south to Key West, and west along the northern coastline of the Gulf of Mexico. Coastal marshes and beaches, rivers, inland lakes and marshes, river banks, and the land immediately surrounding all are frequented.[12] Fish crows are also found along many river systems inland for quite some distance, having expanded their range along rivers since the early 1900s.[16] Since 2012, fish crows have rapidly expanded into Canada, with breeding populations along Lake Ontario[17], and the Bahamas, with poulations in islands like Grand Bahama and Abaco

Behavior

[edit]
Fish crow while vocalizing

Diet

[edit]
Fish crow eating an egg

Food is taken mainly from the ground or shallow water where the bird hovers and plucks food items out of the water with its feet. The fish crow is omnivorous. It feeds on small crustaceans, such as crabs and shrimps, other invertebrates, stranded fish, and live fish if the situation favors their capture, eggs and nestlings of birds, small reptiles, the fruits of many trees, peanuts, and grains, as well as human scraps where available.[12]

Breeding

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The nest is usually built high in a tree and is often accompanied in nearby trees with other nests of the same species forming small, loose colonies. Usually, four or five eggs are laid. Pale blue-green in colour, they bear blotches of olive-brown.[18] Fish crows build a new nest for each breeding attempt.[19] A pair of fish crows were reported to have raised a young blue jay for multiple weeks.[19]

Conservation

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This species appears to be somewhat more resistant to West Nile virus than the American crow. Survival rates of up to 45% have been reported for fish crows, compared with near zero for American crows.[20]

References

[edit]

Further reading

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[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Fish crow

View on Grokipedia
from Grokipedia
The fish crow (Corvus ossifragus) is a medium-sized bird in the crow family (Corvidae), endemic to the eastern and southeastern United States, where it inhabits wetland and coastal environments such as estuaries, rivers, marshes, and beaches. Measuring 36–40 cm in length and weighing 195–330 g, it has entirely black plumage with a subtle green-purple sheen, closely resembling the American crow (Corvus brachyrhynchos) in appearance but differing in vocalizations and habitat preferences. Fish crows are highly adaptable omnivores, foraging for a diverse diet that includes insects, fish, crabs, eggs, fruits, seeds, carrion, and human food waste, often scavenging along shorelines or in urban areas. They are social birds, typically found in flocks—sometimes mixed with American crows—and are known for their distinctive nasal calls, such as a short "cah" or "uh-uh," which sound like "an American Crow with a bad cold." Diurnal and arboreal, they exhibit territorial behavior during the breeding season (late March to mid-June), when monogamous pairs construct nests in trees near water, laying 2–6 eggs that incubate for 16–19 days before fledging after 32–40 days. Historically confined to coastal regions from to and westward to , the has expanded its range inland and northward along major river systems in recent decades, adapting to suburban, agricultural, and urban settings while maintaining a "Least Concern" . Notable for behaviors like raiding nests of colonial waterbirds for eggs and forming loose breeding colonies, fish crows demonstrate remarkable opportunistic typical of corvids, with an average lifespan of 6–7 years in the wild and a maximum recorded lifespan of 14.5 years.

Taxonomy

Etymology

The scientific name of the fish crow is Corvus ossifragus. The genus name derives from the Latin term for "crow" or "raven," a root commonly used for species in this genus. The specific epithet ossifragus is a Latin compound from os (or ossis, meaning "") and frangere ("to break"), translating to "bone-breaker." This name refers to observations of the bird's foraging behavior, in which it drops hard-shelled prey like onto rocks or other hard surfaces to crack them open, a habit that may have been misinterpreted as involving bones specifically. The common name "fish crow" was first coined by Scottish-American ornithologist Alexander Wilson in 1812, reflecting the species' frequent association with coastal and riverine habitats where it forages on fish and other aquatic prey. In his description, Wilson noted that the bird "is called the Fish Crow, from its being frequently seen near the water, and feeding on fish," distinguishing it from larger inland crows based on reports from local fishermen and his own observations along the Delaware and Schuylkill rivers. This naming emphasized the bird's specialized wetland habits in eastern , as detailed in the fifth volume of Wilson's American Ornithology.

Systematics

The fish crow (Corvus ossifragus) is classified within the family Corvidae, which encompasses crows, ravens, jays, and magpies, and the genus Corvus, a diverse group of approximately 40 species of corvids distributed worldwide. This species is monotypic, with no recognized subspecies, reflecting its relatively uniform morphology and genetics across its range. Molecular phylogenetic analyses place the fish crow within III of the genus Corvus, a primarily Nearctic and radiation that originated in during the . It forms a close sister relationship with the palm crow (C. palmarum) and shares this clade with the Sinaloa crow (C. sinaloae) and (C. imparatus), indicating a shared evolutionary history involving of coastal and island habitats. In contrast, the fish crow diverged earlier from the lineage of the (C. brachyrhynchos), which belongs to the separate VI, a Nearctic group with more continental affinities. The Jamaican crow (C. jamaicensis) is positioned in II, reflecting an independent event from a Palaearctic . Historically, the Sinaloa crow and were treated as subspecies or conspecific with the fish crow, based on morphological similarities such as size and , as noted in early 20th-century classifications. This confusion persisted until vocal and genetic distinctions were clarified, with comprehensive molecular studies in the early confirming their status as distinct species within the same superspecies complex. The fossil record of the fish crow is sparse and primarily limited to North American deposits, underscoring its long-term presence in the region but lacking species-specific evidence from earlier epochs. Remains include over 80 specimens from (Rancholabrean) sites in and five from late (Irvingtonian) contexts in the same area, dating to approximately 2 million years ago. The broader genus traces its origins to the mid-Miocene, around 17.5 million years ago, based on dated molecular phylogenies and early corvid fossils from .

Description

Physical characteristics

The fish crow (Corvus ossifragus) measures 36–40 cm in length, with a wingspan of approximately 84 cm and a weight ranging from 195–330 g. Males are slightly larger than females, but there is no other in plumage or structure. Overall, the species is smaller and slimmer than the (Corvus brachyrhynchos), aiding in visual identification when the two occur together. Adults exhibit entirely black plumage with a glossy blue-green or purplish sheen, particularly evident on the wings and tail; the feathers appear smoother and silkier compared to those of related corvids like the . The bill is heavy, glossy, and short, slightly slimmer than that of the , while the legs are sturdy and black, scaled on the front and smooth on the back. The wings are broad but slightly more tapered in shape, contributing to a more pointed appearance in flight relative to congeners. Juveniles resemble adults in overall form but possess duller , with the body and head feathers appearing dark brown—nearly black—and looser or fluffier in texture; the wings and tail remain blacker with subtle greenish reflections. They acquire the full glossy sheen by their first winter following the post-juvenile molt.

Vocalizations

The fish crow (Corvus ossifragus) produces a variety of vocalizations that are essential for species identification, particularly in regions where its range overlaps with that of the American crow (Corvus brachyrhynchos). The primary call is a distinctive nasal, two-syllable "uh-uh" or "cah-ah," often described as querulous and higher-pitched than the American crow's deeper, hoarser "caw." This call may be repeated in a series of smoother, more liquid "cahh-cahh-cahh" notes, which lack the resonant quality of the American crow's "caw-caw." Female fish crows typically deliver these calls at a higher pitch than males. Alarm and contact calls include a sharp, single "cah" or rattling sounds used to signal potential threats, as well as softer, nasal variants like "awwr" or "kwok" in less urgent social interactions. These vocalizations are more reliable for distinguishing the fish crow from the than visual cues alone, especially at a distance or in flight, given the subtle size differences between the species. Regional variations in these calls are minimal across the fish crow's range from the to the Gulf Coast. The fish crow has a faster wingbeat frequency compared to the , though these are rarely diagnostic for identification purposes.

Distribution and habitat

Geographic range

The fish crow (Corvus ossifragus) is primarily distributed across the eastern and , with its core range encompassing coastal and near-coastal areas from southward through the Atlantic seaboard to the , and westward along the Gulf Coast to eastern . Inland, populations extend along major river systems, including the valley up to and portions of the lower . This distribution reflects the species' strong association with aquatic and riparian environments throughout its established territory. In recent decades, the fish crow has exhibited northward expansion, reaching coastal where breeding was first confirmed in 1985, and further into along , with the first successful breeding in documented in 2012. The species has established breeding populations farther west in (first documented in 2009, with breeding records since 2011) and (with nesting confirmed in Polk County in 2024), alongside vagrant records in and increasing breeding in since the late , demonstrating ongoing range extension into the Midwest. As of 2025, the species continues to expand inland, with recent breeding confirmations in (2024) and increasing presence in Midwestern states along river systems. The is non-migratory and maintains year-round residency within its range, with stable populations showing no significant seasonal movements; however, some northern inland groups may shift locally during winter. Historically, the fish crow's range has remained relatively stable since the , though slight inland expansions along corridors occurred post-1950s, facilitated by habitat modifications such as riverine development and reduced disturbance in altered landscapes.

Habitat preferences

The fish crow (Corvus ossifragus) exhibits a strong preference for habitats closely tied to aquatic environments, primarily coastal wetlands, , tidal flats, and riverine forests, where proximity to facilitates on marine and freshwater resources. These birds are most abundant in temperate zones at or near , with elevations typically at 0 m, reflecting their reliance on estuaries, rivers, lakes, brackish waters, ponds, and coastal marshes. In comparison to the (Corvus brachyrhynchos), fish crows select nesting sites significantly closer to the water's edge and waterbird colonies, often in natural coastal dunes or islands rather than inland or developed areas. Inland from coastal zones, fish crows favor swamps, bottomland forests, and urban or suburban edges adjacent to water bodies, such as along major systems or near lakes, while generally avoiding arid uplands or dry interior forests. During the breeding season, they occupy and oak-hickory forests in the , shifting to oak woodlands near shorelines or stands in winter. This distribution underscores their limited versatility in non-aquatic habitats compared to the more adaptable , which readily uses lawns, garbage sources, and exotic evergreens farther from water. Nesting occurs in tall trees such as pines and oaks situated near , frequently in loose colonies within these preferred ecosystems. Fish crows demonstrate notable tolerance for human-altered landscapes, including urban parks, docks, and landfills proximate to waterways, where they exploit available resources without venturing into purely terrestrial or arid settings. Their choices are primarily driven by the availability of prey like , , and eggs in and riparian zones, limiting their range expansion into drier environments.

Behavior

Diet and foraging

The fish crow (Corvus ossifragus) exhibits an omnivorous diet dominated by aquatic prey, including , , , , and mollusks, alongside turtle eggs and the eggs and nestlings of other s obtained through nest-robbing. Insects, such as beetles and caterpillars, fruits like berries and mulberries, grains, and human food scraps, including garbage and carrion, supplement this intake, reflecting the bird's opportunistic feeding strategy. Foraging behaviors are adapted to coastal and wetland environments, where fish crows probe mudflats and tidal zones with their bills to uncover , wade in shallow water to capture and crustaceans, and scavenge beaches for stranded and carrion. They also drop mollusks from the air onto hard surfaces, such as rocks, to break open the shells. They frequently raid nests of colonial waterbirds, such as , ibises, gulls, and terns, as well as solitary species like rails and songbirds, destroying eggs or consuming nestlings when adults are absent; additionally, they dig up buried turtle eggs, including those of species like the . Dietary preferences shift seasonally, with marine prey like and comprising a larger proportion during winter when crows congregate in coastal flocks, while and fruits increase in summer as breeding activities intensify inland. Group foraging is prevalent in tidal marshes and estuaries, where loose flocks coordinate to exploit abundant resources such as exposed during low . The common name "fish crow" derives from the prominence of fish in the diet, particularly in coastal studies where aquatic items form a substantial component of consumption.

Breeding

The fish crow breeds seasonally, with the timing varying by ; in southern regions, nesting begins in late and extends through , while in northern parts of the range, it starts in and may continue into . Pairs are monogamous and typically territorial around the nest site, though they may breed semi-colonially with multiple nests spaced within 100 yards of each other, particularly in areas. Only one brood is raised per year, and pairs do not reuse nests from previous seasons. Nests are bulky structures, approximately 19 inches across with a 5-inch-deep , constructed primarily by the female over 9–10 days using sticks, or dung, bark, , hair, and needles for lining. They are placed near the tops of trees, such as evergreens, species, palms, or mangroves, often 10–20 meters above ground in habitats adjacent to water bodies like swamps or marshes. The female lays a of 2–6 eggs, most commonly 4–5, which are pale bluish-green and marked with brown or olive blotches; each measures about 1.3–1.6 inches long by 1.0–1.2 inches wide. Incubation lasts 16–19 days and is performed solely by the , who is provisioned with by the male during this period. Both parents share in feeding the altricial young, which remain in the nest for 32–40 days before fledging. After fledging, the juveniles remain dependent on the parents for approximately 1–2 months, during which time both adults continue to provide and guidance in and flying skills. Nest success is often limited by high predation rates, particularly from raccoons, rat snakes, and eastern gray squirrels, which commonly target eggs and nestlings during the breeding season.

Social behavior

Fish crows typically form small family groups during and shortly after the breeding season, which may consist of breeding pairs and their offspring remaining together for over a month post-fledging. Outside the breeding period, they exhibit heightened , congregating in flocks numbering in the hundreds or even thousands near abundant food sources. These large gatherings often occur in winter, where fish crows form communal roosts of similar sizes, particularly along urban edges and margins. In these groups, fish crows engage in cooperative interactions, such as mobbing predators like hawks, , and raccoons, where individuals flock together in response to alarm calls to harass and drive away threats. They also perform allopreening, in which group members groom each other's feathers, often initiated by a solicitation posture involving an arched neck, fluffed feathers, and sidling approach. Fish crows occasionally associate interspecifically with American , sharing roosts and foraging areas, though they typically yield to the larger species during disputes. Communication plays a key role in group coordination, with fish crows employing distinct nasal calls—such as their characteristic "uh-oh" or rattling sounds—to signal assembly at roosts and alert others to dangers. Fish crows demonstrate boldness in human-altered environments, frequently scavenging trash from landfills, dumpsters, and urban areas, which allows them to thrive near people. This adaptability sometimes leads to conflicts, as they are regarded as pests at coastal beaches where they raid and nests for eggs.

Conservation

Population status

The fish crow (Corvus ossifragus) maintains a global population estimated at 470,000 mature individuals (estimated in 2011), with nearly the entire breeding population occurring within the and a small breeding population in southern since 2012. This estimate reflects data from Partners in Flight, which also indicates a slightly positive annual population trend based on 2024 assessments. Regionally, the species has shown expansion at its northern range limits, with confirmed breeding in , , since 2012, marking a rapid northward shift from the . Population densities remain highest in the , particularly in coastal and habitats from to , where relative abundance is notably elevated compared to northern extensions. The International Union for Conservation of Nature (IUCN) classifies the fish crow as Least Concern as of its most recent assessment in 2025, reflecting its large range and lack of immediate risks. NatureServe assigns it a global rank of Secure (G5), indicating it is widespread and abundant across its range without significant vulnerabilities. Population monitoring occurs through multiple standardized programs, including the North American Breeding Bird Survey, eBird submissions, and Audubon Christmas Bird Counts, which collectively show no significant declines based on data available as of 2025 (up to 2023 for eBird and 2024 for other surveys) and support the observed stable to increasing trajectory.

Threats

The Fish Crow faces habitat loss primarily from coastal development and the drainage of wetlands, which reduces available nesting and foraging sites in marshes, estuaries, and riverine areas. These activities fragment coastal ecosystems, limiting access to tidal flats and swamps essential for the species' diet and breeding. Nest predation by invasive and native species, such as raccoons (Procyon lotor), poses a significant risk during the nesting season, with predators targeting eggs and fledglings in low-lying trees and shrubs. Rat snakes (Pantherophis spp.) and eastern gray squirrels (Sciurus carolinensis) also commonly raid nests, contributing to reduced in affected areas. Diseases affect Fish Crows, though impacts vary; West Nile virus (WNV) causes mortality, but survival rates are higher than in closely related American Crows (Corvus brachyrhynchos), with experimental challenges showing approximately 50% survival in unvaccinated individuals compared to near-100% mortality in American Crows from early strains. Avian pox, caused by avipoxviruses, occurs occasionally in corvids, leading to lesions on unfeathered skin that can impair feeding and increase susceptibility to secondary infections. Additional risks include collisions with windows and vehicles in expanding urban and suburban environments, where Fish Crows increasingly near human . exposure through contaminated prey, such as and small vertebrates in treated coastal habitats, can lead to sublethal effects like reduced . alters tidal habitats through sea-level rise and increased storm frequency, potentially inundating low-elevation nesting sites and shifting prey availability. The Fish Crow is protected under the Migratory Bird Treaty Act of 1918, which prohibits take without permits and supports broader conservation efforts. It benefits indirectly from wetland restoration projects that enhance coastal habitats, improving foraging and nesting opportunities without species-specific interventions. Given its stable to increasing population trends, no targeted management programs are currently implemented.

References

  1. https://www.allaboutbirds.org/guide/Fish_Crow/overview
  2. https://animaldiversity.org/accounts/Corvus_ossifragus/
  3. https://birdsoftheworld.org/bow/species/fiscro/cur/introduction
  4. https://www.biodiversitylibrary.org/item/175520
  5. https://datazone.birdlife.org/species/factsheet/fish-crow-corvus-ossifragus
  6. https://bmcecolevol.biomedcentral.com/articles/10.1186/1471-2148-12-72
  7. https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=1615&context=ffn
  8. https://www.allaboutbirds.org/guide/Tamaulipas_Crow/overview
  9. https://birdsoftheworld.org/bow/species/fiscro/cur/systematics
  10. https://www.allaboutbirds.org/guide/Fish_Crow/id
  11. https://www.nationalgeographic.com/animals/birds/facts/fish-crow
  12. https://www.birds.cornell.edu/crows/FishCrow.htm
  13. https://birdsoftheworld.org/bow/species/fiscro/cur/appearance
  14. https://www.allaboutbirds.org/guide/Fish_Crow/sounds
  15. https://www.audubon.org/field-guide/bird/fish-crow
  16. http://oldbird.org/pubs/fcmb/species/crows/ficr/ficr.htm
  17. https://www.audubon.org/magazine/birdist-rule-65-how-tell-difference-between-crows
  18. https://birdsoftheworld.org/bow/species/fiscro/cur/distribution
  19. https://www.birds.cornell.edu/crows/nyrange.htm
  20. https://www.birdsontario.org/crows/
  21. https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=2084&context=nebbirdrev
  22. https://www.ksbirds.org/kos/bulletin/Vol60No4.pdf
  23. https://birds.outdoornebraska.gov/fish-crow/
  24. https://www.audubon.org/magazine/long-overlooked-and-understudied-fish-crow-worth-your-attention
  25. https://www.carolinabirdclub.org/chat/issues/1975/v39n4ficr.pdf
  26. https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=1539&context=tos_bulletin
  27. https://www.allaboutbirds.org/guide/Fish_Crow/lifehistory
  28. https://www.tn.gov/twra/wildlife/birds/fish-crow.html
  29. https://birdsoftheworld.org/bow/species/fiscro/cur/behavior
  30. https://earthlife.net/fish-crows/
  31. https://wildlife.org/wsb-electric-shocks-deter-fish-crows-from-seabird-colonies/
  32. https://science.ebird.org/status-and-trends/species/fiscro/abundance-map
  33. https://guides.nynhp.org/status/2.101678/
  34. https://science.ebird.org/status-and-trends/species/fiscro/range-map
  35. https://cwhl.vet.cornell.edu/disease/avian-pox
  36. https://www.researchgate.net/publication/259562592_Bird-building_collisions_in_the_United_States_Estimates_of_annual_mortality_and_species_vulnerability
  37. https://abcbirds.org/program/pesticides/
  38. https://www.audubon.org/climate/survivalbydegrees/state/us/va
  39. https://www.fws.gov/project/habitat-restoration
  40. https://birdsoftheworld.org/bow/species/fiscro/cur/demography
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