Overview

Brief Summary

The Fish Crow (Corvus ossifragus) is year-round resident locally from New York and Massachusetts south along the Atlantic-Gulf Coast to southern Florida and west to southern Texas, as well as inland along major river systems. It is very common in parts of its range. Fish Crows are found around tidewater marshes, low valleys along eastern river systems, and in Baldcypress (Taxodium) swamps; in recent decades, the interior range has expanded and the northern boundary of the range has extended northward. Although in most parts of its range it is a permanent resident, in winter Fish Crows withdraw from some parts of their inland range. In the winter, Fish Crows are often seen in mixed flocks with American Crows, when they may also be found on farmland, in towns, and around garbage dumps. The Fish Crow is one of only about a dozen bird species that are endemic to the United States (i.e., found nowhere else in the world).

The Fish Crow closely resembles the American Crow (Corvus brachyrhynchos), but is smaller overall and has a smaller bill, smaller feet, and shorter legs, as well as more pointed wings and a faster wingbeat. However, it is best distinguished by its quite different common call, a nasal two-note call with the second note lower in pitch (however, juvenile and sometimes adult American Crows produce similar calls).

Fish Crows may feed on an extraordinary range of foods, including carrion, crustaceans, insects, berries, seeds, nuts, bird eggs, turtle eggs, and human garbage. They generally forage in flocks, mainly by walking, especially along the shore or in very shallow water. They may drop mollusks from the air to break open their shells. In colonies of herons and other waterbirds, if the nesting adults are frightened off their nests, Fish Crows may feast on their eggs.

Fish Crows often nest in loose colonies of a few pairs. Courtship may involve the male and female flying close together in a gliding display flight. The nest is placed in an upright fork of a tree or shrub. The nest may be placed very low at coastal sites or quite high in deciduous trees in inland swamps (1 to 21 m above the ground or even higher) The nest (which is probably built by both sexes) is a bulky platform of sticks and strips of bark lined with softer materials such as grass,rootlets, hair, feathers, paper, pine needles, and even manure. The female lays 4 to 5 dull blue-green to gray-green eggs blotched with brown and gray. Incubation is by the female (possibly assisted by the male) for 16 to 18 days. Nestlings are probably fed by both parents. The age at which young leave the nest is uncertain, but is probably around 3 to 4 weeks.

(Kaufman 1996; AOU 1998; Dunn and Alderfer 2011)

  • American Ornithologists' Union. 1998. Check-list of North American Birds, 7th edition. American Ornithologists' Union, Washington, D.C.
  • Dunn, J.L. and J. Alderfer. 2011. National Geographic Field Guide to the Birds of North America. National Geographic Society, Washington, D.C.
  • Kaufman, K. 1996. Lives of North American Birds. Houghton Mifflin, Boston.
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Distribution

Global Range: Resident from New York and Massachusetts south along Atlantic-Gulf coast to southern Florida, and west to southern Texas; inland along major river systems to northwestern Illinois, southwestern Kentucky, western Tennessee, central Georgia, western South Carolina, northwestern North Carolina, central Virginia, central Maryland, eastern West Virginia, and central Pennsylvania (AOU 1983). Range expanding inland in Carolinas and Georgia (McNair 1989).

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endemic to a single nation

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National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Range

Eastern US (New England to s Texas).
  • Clements, J. F., T. S. Schulenberg, M. J. Iliff, D. Roberson, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2014. The eBird/Clements checklist of birds of the world: Version 6.9. Downloaded from http://www.birds.cornell.edu/clementschecklist/download/

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Physical Description

Size

Length: 39 cm

Weight: 300 grams

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Ecology

Habitat

Habitat and Ecology

Systems
  • Terrestrial
  • Freshwater
  • Marine
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Comments: Beaches, bays, lagoons, inlets, swamps, near marshes, and, less frequently, deciduous or coniferous woodland. In inland situations, primarily in baldcypress swamps and along major watercourses; also garbage dumps and towns (McNair 1989). Nests in tree, usually high, but sometimes as low as 2 m (Harrison 1978).

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Migration

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

NGS (1983) indicated only breeding season occurrence in northern part of range in Mississippi River drainage.

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Trophic Strategy

Comments: Eats shoreline invertebrates, eggs of shore and sea birds and turtles, insects and other terrestrial invertebrates, various fruits and berries, carrion (Terres 1980).

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Associations

Known prey organisms

Corvus ossifragus preys on:
Egretta thula

This list may not be complete but is based on published studies.
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Life History and Behavior

Life Expectancy

Lifespan, longevity, and ageing

Maximum longevity: 14.5 years (wild)
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Reproduction

Clutch size is 4-5. Incubation, apparently by both sexes, lasts 16-18 days. Young leave nest at 21 days or more. Usually nests in small colony of well-spaced pairs.

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Molecular Biology and Genetics

Molecular Biology

Barcode data: Corvus ossifragus

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 2 barcode sequences available from BOLD and GenBank.

Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.

See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

TCTGGTACTAATCTTCGGGGCATGAGCCGGAATAGTAGGTACCGCCCTAAGTATCCTTATCCGAGCAGAACTAGGCCAACCTGGTGCTCTACTAGGAGATGATCAAATCTACAATGTAATCGTTACAGCTCATGCTTTCGTCATAATTTTCTTCATAGTGATACCAATTATGATCGGAGGGTTCGGGAACTGACTAGTCCCCCTAATAATTGGTGCCCCAGACATAGCATTCCCACGAATAAACAACATAAGCTTCTGACTCCTCCCACCTTCATTCCTTCTACTGCTAGCCTCCTCCACAGTAGAAGCAGGAGCAGGAACAGGATGAACCGTATACCCACCACTAGCTGGTAACCTAGCCCACGCTGGAGCATCAGTCGACCTGGCCATCTTCTCACTACATCTAGCAGGAATCTCCTCCATCCTAGGAGCAATCAACTTCATCACTACAGCAATCAACATAAAACCTCCAGCCCTATCACAATACCAAACTCCTCTATTCGTGTGATCAGTCCTAATTACCGCAGTACTACTCCTTCTCTCCCTACCCGTTCTTGCTGCCGGAATCACTATGCTTCTAACAGACCGTAACCTAAACACTACGTTCTTCGACCCAGCAGGTGGAGGAGACCCAGTACTATACCAACATCTGNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
-- end --

Download FASTA File

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Statistics of barcoding coverage: Corvus ossifragus

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 2
Specimens with Barcodes: 2
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2012

Assessor/s
BirdLife International

Reviewer/s
Butchart, S. & Symes, A.

Contributor/s

Justification
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
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National NatureServe Conservation Status

United States

Rounded National Status Rank: N5 - Secure

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NatureServe Conservation Status

Rounded Global Status Rank: G5 - Secure

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Population

Population Trend
Increasing
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Wikipedia

Fish crow

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

Taxonomy[edit]

The fish crow was first described by Alexander Wilson in 1812. The latest genetic testing now seems to indicate that this species is close to the Sinaloan crow (Corvus sinaloae) and the Tamaulipas crow (Corvus imparatus), and not as close to the American crow (Corvus brachyrhynchos) as outward signs would suggest.[citation needed]

Description[edit]

Fish crow in flight at the marshes of Core Sound in North Carolina.
Composite image of fish crows
Fish crow eating an egg

The fish crow is superficially similar to the American crow but is smaller (36–41 cm in length) and has a more silky smooth plumage by comparison. 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 side by side or, when heard calling. The bill is usually somewhat slimmer than the American crow, but is only readily distinguishable if both species are seen together.[2]

Visual differentiation from the American crow is extremely difficult and often inaccurate.[3] 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".[4]

Distribution and habitat[edit]

This species occurs on the eastern seaboard of the United States from the state of Rhode Island south to Key West, and west along the northern coastline of the Gulf of Mexico and follows many river systems inland for quite some distance. Coastal marshes and beaches are frequented, also rivers, inland lakes and marshes, river banks, and the land immediately surrounding all.[2]

Behavior[edit]

Diet[edit]

Food is taken mainly from the ground and even in shallow water where the bird will hover and pluck food items out of the water with its feet. The fish crow is omnivorous. It will feed 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.[2]

Breeding[edit]

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. There are usually 4-5 eggs laid. Pale blue-green in colour, they bear blotches of olive-brown.[5]

Conservation[edit]

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 the American species.[6]

References[edit]

  1. ^ BirdLife International (2012). "Corvus ossifragus". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013. 
  2. ^ a b c Goodwin, p. 92
  3. ^ Cornell Lab of Ornithology, Fish Crow - Physical Characters
  4. ^ Cornell Lab of Ornithology, Fish Crow - Voice
  5. ^ Goodwin, p. 93
  6. ^ "West Nile and Ravens". Rhode Island Department of Environmental Management. Retrieved 28 April 2014. 

Cited text[edit]

  • Goodwin D. (1983). Crows of the World. Queensland University Press, St Lucia, Qld. ISBN 0-7022-1015-3. 
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Names and Taxonomy

Taxonomy

Comments: Considered conspecific with C. IMPARATUS by some authors (AOU 1983). May or may not constitute a superspecies with C. SINALOAE, C. IMPARATUS, and C. PALMARUM (AOU 1998).

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