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Not everyone realizes it, but there are two kinds of crows across much of the eastern United States. Looking almost identical to the ubiquitous American Crow, Fish Crows are tough to identify until you learn their nasal calls. Look for them around bodies of water, usually in flocks and sometimes with American Crows. They are supreme generalists, eating just about anything they can find. Fish Crows have expanded their range inland and northward along major river systems in recent decades. [ facts source: Cornell University – All About Birds ]
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When Fish Crows find a good source of food, they may cache the surplus for later. These hiding places can be in grass, in clumps of Spanish moss, or in crevices in tree bark. Nesting adults may use these caches when feeding their young. Fish Crows are inveterate nest-robbers, raiding the nests of many kinds of waterbirds and songbirds, as well as finding and digging up the eggs of turtles. They also harass and steal food from crows, gulls, ibis, and Ospreys. Members of a mated pair frequently preen the back of each other’s head. One nesting pair of Fish Crows adopted a fledgling Blue Jay that appeared in their nest. The crows fed the jay for two weeks before it disappeared. Fish Crows build a new nest for each breeding attempt. The nests are well-made, and one small area may have existing nests from up to four different years. The oldest known Fish Crow was 14 years, 6 months old.
Fish 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.
Like 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.
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, red cedar 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.
Fish 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.
Fish 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.
Fish Crows have generally increased their range and numbers since the mid-twentieth century, although most of these gains came before 1980. West Nile Virus killed many Fish Crows, as it did other crow and jay species, in the early 2000’s, but Breeding Bird Survey indicate 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.