Fish Crow Life History

Habitat

Habitat ShorelinesFish Crows live along beaches, marshes, estuaries, lakes, and rivers. They have adjusted well to human habitation and are expanding their range northward and inland. In addition to waterfront habitats, look for them inland around agricultural fields, urban and suburban areas, golf courses and wooded neighborhoods. Away from water, they tend to be less common in rural areas than American Crows. In winter, Fish Crows gather in large flocks near ready supplies of food such as landfills, feedlots, and estuaries. Back to top

Food

Food OmnivoreLike most of its relatives, Fish Crows will eat almost anything, including carrion, trash, nestlings and eggs of other birds, berries, fruit, and grain, and any items they can steal from other birds. Their association with water leads them to eat crabs, marine invertebrates, and turtle eggs more than other crows. They are well-known predators of other birds’ nests and may specialize on raiding the nests of colonial waterbirds, including Double-crested Cormorants, ibis, herons, gulls, and terns, as well as solitary-nesting species such as rails, ducks, plovers, and songbirds such as Blue Jays, Northern Mockingbirds, Brown Thrashers, Common Grackles, and Red-winged Blackbirds. Back to top

Nesting

Nest Placement

Nest TreeFish Crows put their nests near the tops of evergreens, deciduous trees, palms, and mangroves depending on what’s available. They may nest in heron colonies and raid the herons’ nests. Though they’re not strictly colonial themselves, pairs may nest within 100 yards of each other, particularly in marshes where nest trees are scarce.

Nest Description

The female gathers nests materials and builds the nest herself. A male may accompany her but does not help. She makes a bulky nest of sticks taken from deciduous trees, filling the nest cup with soil, redcedar or grapevine bark, Spanish moss, palm fibers, hair, and pine needles. The nest takes 10 days or more to make, and the finished product is about 19 inches across with a cup about 5 inches across.

Nesting Facts
Clutch Size:2-6 eggs
Number of Broods:1 brood
Egg Length:1.3-1.6 in (3.3-4.2 cm)
Egg Width:1.0-1.2 in (2.5-3 cm)
Incubation Period:16-19 days
Nestling Period:32-40 days
Egg Description:Pale bluish green with brown markings.
Condition at Hatching:Naked and helpless.
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Behavior

Behavior Ground ForagerFish Crows, like other corvids (crows and jays), are intelligent, curious, social animals. Breeding pairs form in the summer, but in winter they gather into flocks of hundreds to thousands. Young Fish Crows, like other crow species, often play with objects that they find—one was seen hanging upside down and swinging from a weeping willow branch. Fish Crows join together (and may join American Crows) to mob hawks and other predators including raccoons, owls, and humans, driving them away. They forage around gulls and may steal food from them, as the gulls themselves often do from other seabirds. When in a dispute with an American Crow, Fish Crows (which are slightly smaller) always give ground. Back to top

Conservation

Conservation Low ConcernFish Crow populations slightly increased between 1966 and 2015, according to the North American Breeding Bird Survey, and their range has expanded during this time. Partners in Flight estimates a global breeding population at 450,000 with 100% living in the U.S. The species rates a 10 out of 20 on the Continental Concern Score. Fish Crow is not on the 2016 State of North America's Birds' Watch List. West Nile Virus killed many Fish Crows, as it did other crow and jay species, in the early 2000s, but the Breeding Bird Survey indicates that its numbers are rebounding. The range expansion of Fish Crows, which often raid nests, may affect some species of breeding birds, especially colonially nesting species. Although crows are protected by the Migratory Bird Treaty Act, because they have been regarded as pest species, states retained the right to allow hunting of them. Fish Crows are still hunted in some states.Back to top

Credits

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

McGowan, Kevin J. 2001. Fish Crow (Corvus ossifragus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski, Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley guide to birds, second edition. Alfred A. Knopf, New York, USA.

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