The geographic range of fish crows () is limited to the Nearctic range. Fish crows are native to the east coast of the United States but have been found as far west as Nebraska, Wyoming, Kansas and Iowa (Jorgenson et al., 2009). Their northern range extends to Maine and their southern range extends to Florida (McGowan, 2001).
The migratory habits of fish crows have not been studied in depth. However, Hamel (1992) suggests that these crows utilize the coastal regions of their range in the winter. They move more to the inland portions of their range during the breeding season. (Hamel, 1992; Jones, 1990; Jorgensen, et al., 2009; McGowan, 2001; Wells and McGowan, 1991)
Fish crows are most commonly found in temperate forests near aquatic habitats. These habitats include estuaries, rivers, lakes, brackish water, lakes, ponds, the coast, and other riparian biomes (elevation 0 m). Fish crows are also found in marshes and swamps. These crows have been found in urban, suburban, and agricultural areas. In the southeastern part of the United States, fish crows can be found during breeding season in pine (Pinus) forests and in oak (Quercus)-hickory (Carya) forests, while in the winter season they can be found in oak forests close to shorelines and in Virginia pines (Pinus virginiana). (Hamel, 1992; McGowan, 2001)
Fish crows are completely black in coloration, with adults having a green-purple sheen on their plumage. The feathers on their wings and tails tend to age over time, fading to grey on the tips. Their eyes are black, and their bills are glossy and short. Their legs are black and scaled on the anterior side but smooth posteriorly. The average basal metabolic rate is 0.85 kcal per second. On average, adult fish crows weigh 195 to 330 g. Body lengths range from 36 to 40 cm. Average wingspan is unknown.
Fish crows go through several developmental stages. When first hatched, chicks have a drab, brown down or yellow patches without down. The insides of juvenile mouths are pink and their eyes are closed right after hatching. The juvenile stage is characterized by the completion of the pre-juvenile molt. Juvenile plumage is black on the wings and tail, with the body and head feathers a dark brown - almost black. Juvenile feathers are looser and fluffier than adult feathers. Their eyes darken to a gray color. Average size and length for hatchling and immature fish crows is unknown.
Adult fish crows go through two molts throughout the year, the first from July through late October and the second occurring from late June through late July a year later. There are very few differences between the two molts. The first molt is characterized by worn out feathers and a bluer undertone to the feathers. The second molt gives the feathers on the throat a more distinct rough pattern.
While there are no differences in plumage color between male and female fish crows, there is a slight size difference between the sexes. Male fish crows are slightly larger than the female fish crows. The exact size difference has not been reported.
Fish crows are similar to American crows (Corvus brachyrhynchos), but fish crows are smaller than American crows. Fish crows also have a unique call that sounds like a more nasal version of calls American crows make. When making these calls, the neck feathers of fish crows will fluff up. (Jorgensen, et al., 2009; Laiolo and Rolando, 2003; McGowan, 2001; Poole, 1938)
Fish crows breed seasonally and are monogamous during breeding seasons. Courtship displays between pairs are uncommon, although McGowan (2001) summarized mating activities for these crows. Males may initiate mating in one of two ways – males either feed potential mates or they somehow tap the beaks of females. If females are receptive, they initiate a three-step process that involves stiffening their bodies, hunkering down, and spreading out the feathers on their tails. After mating, pairs will sit close together and sometimes pluck at nearby twigs. McGowan also summarized one incident of a crow displaying as it carried materials to the nest. It was described as a “butterfly” flight pattern.
Fish crows have been observed building nests in mid-April in New York and Virginia, and in late March through mid-April in Florida. Both males and females help build nests. Nests are built during the day, and generally take 9 or more days to complete. Nests are not reused each season and are typically built close to the tops of trees. These nests are made out of sticks and twigs in a cup shape. The sticks used in fish crow nests have been observed to have a diameter of 4 to 8 mm. Mud or dung is also used in the outer construction of these nests. Inner linings of nests have softer materials, such as bark fibers, hair, and pine needles. One nest in New York was observed to have outer dimensions of 50 cm by 37 cm, with inner dimensions of 12.5 cm by 12.5 cm (McGowan, 2001). (McGowan, 2001)
Fish crows breed once a year from late March to mid-June. These birds only have one brood per season, and if disturbed early enough in the season, they will re-nest. Fish crows lay 2 to 6 eggs per season. Eggs are elliptical in shape and are roughly 37.8 mm long by 27.3 mm wide. Egg masses have not been recorded, but empty eggshells have been observed to weigh 0.882 g. The outside texture of eggs are slightly rough and glossy. They are pale blue-green with brown speckling.
Only female fish crows incubate eggs, which take 16 to 19 days to hatch. Birth masses for young fish crows is currently unknown. Young fish crows fledge 32 to 40 days after hatching and are independent about a month after fledging. Both males and females reach sexual maturity at about 15 months of age. (Hamel, 1992; Harrison, 1978; Headstrom, 1970; McGowan, 2001; Reese, 2015)
Both male and female fish crows help build nests. After laying eggs, female fish crows stay at their nests to brood and keep eggs warm while males forage for food. Male fish crows also protect the nest and females from predators. After eggs hatch, both female and male fish crows help feed young, and male fish crows continue to protect young from predators. Both parents teach young how to forage and fly. This continues until juveniles fledge and become independent. (McGowan, 2001)
Fish crows in the wild are known to live for 6 to 7 years on average, with the oldest recorded age being 14.5 years. Lifespan limitations in the wild include predation (especially nest predators), hunting, exposure, and collisions with cars. They are kept in captivity for research purposes, but lifespans have not been reported. (Clapp, 1983; McGowan, 2001)
Fish crows are arboreal, living in trees near bodies of water. They move around mostly by flying, but have been observed hopping around on the ground while foraging. Fish crows have migratory patterns, but are not true migratory birds. Fish crows move further inland during warmer seasons and move back towards the shores during colder seasons. They are active during the day and also migrate during the day. Fish crows leave their overwintering territories and search for breeding territories from March to April, and leave their breeding territories in September. Timing differs across their geographic range.
Fish crows scratch their heads indirectly, using their feet to push their wings forward towards their heads. They bathe by putting their chest in the water, then flapping their wings in the water. They then throw water onto their backs. Fish crows also bathe in the rain when possible. These birds preen each other and their nestlings. Fish crows sunbathe on the ground or in trees with their wings slightly extended and their bills slightly agape.
Outside of breeding season, fish crows will roost together in trees or marshes. These birds will also roost with other species of birds such as American crows (Corvus brachyrhynchos), great blue herons (Ardea herodias), great egrets (Ardea alba), snowy egrets (Egretta thula), little blue herons (Egretta caerulea), tricolored herons (Egretta tricolor), and green herons (Butorides virescens). Fish crows also roost with gulls in order to steal their eggs.
Fish crows are territorial when it comes to protecting their nests. Like other crows, fish crows will peck at other birds or try to grab their legs. Fish crows will also pull at the tails of other birds. Fighting fish crows will sometimes fall out of trees. They chase predators away from nests by diving down at them. Mobbing is a common behavior in fish crows. Fish crows have a specific threat posture where they will lower their heads and spread out their wings while walking sideways towards their opponent. Certain fish crow calls also indicate aggression, such as aggressive rattle calls. After a fight, an appeasement display by losing fish crows occurs. In this display, they do begging calls and lower their bodies.
Fish crows nest close to one another but are not a colonial species. These birds are social but have no observed social hierarchies. Fish crows are most social during non-breeding season. When an alarm call is sounded, fish crows will flock together to mob predators. Young fish crows will play with objects. Fish crows communicate primarily through calls, vocalizing throughout the day for different reasons. They are more vocal during breeding season, with more begging calls being used by females and young. Specific calls are used to indicate territory protection. Tactile communication happens during shows of aggression (mobbing behaviors and fighting), breeding, and caring for young.
Reproductive behaviors include finding a mate, building nests, mating, and caring for young. Courtship displays between pairs are uncommon, but there was an incident described by McGowan (2001) where a crow flew in a pattern similar to a "butterfly" while carrying materials to the nest. Both males and females build nests during the day, which take about 9 days to build on average. Males initiate mating by either feeding potential mates or touching their beaks. If females are receptive they stiffen their bodies, bend down, and spread their tail feathers out. After mating, pairs sit close together and sometimes pluck at nearby twigs. Males primarily protect the nests, young, and females. After eggs hatch, males will bring food back to the nest for females and young, and both females and males will take care of fecal sacs produced by young. Both males and females help raise hatchlings. (Hamel, 1992; Laiolo and Rolando, 2003; McGowan, 2001; Montevecchi, 1978; Reese, 2015; Santisteban, et al., 2002; Shields and Parnell, 1986; Zerega, 1880)
Home ranges for fish crows have not been reported, but McGowan (2001) states that these crows travel at least 500 m from their nests. They defend territory within a small range of their nests, but exact measurements have not been reported. (McGowan, 2001)
Fish crows have a repetitive set of vocalizations. Female fish crows have a higher pitched call than males. They do not use songs to communicate but have a very distinct call. This is a more nasal version of calls American crows (Corvus brachyrhynchos) make, described as "uh-uh" or "cawk." Fish crows vocalize daily and throughout the day.
McGowan (2001) states that "awwr" calls are used in protecting or claiming territory from other fish crows. Intraspecific communication calls such as a drawn-out "awwr" calls are used as a mobbing call in relation to potential predators. Aggressive rattles are also used to show aggression.
Fish crows tend to be more vocal during breeding season. Begging calls are used by nestlings, fledglings, and breeding females, and is described as a higher pitched "awwr" call. Parents use feeding calls to wake up their young to give them food.
As for tactile communications, most instances occur during shows of aggression (such as mobbing), breeding, or interaction with young. Fish crows have been observed attacking other fish crows by pecking, grabbing, or pulling their tails. There are no known courtship displays. Before breeding, male fish crows either touch or feed their female mates. During breeding, males step on the backs of females. After breeding, pairs sit close together. While brooding, males feed the females. Fecal sacs are presented by the young each time they defecate and are either eaten or removed by the parents.
While no sources on fish crows specifically state that they can see in color, it is assumed that they can see in color. Some visual displays of aggression can occur (a threat posture where crows will arch their necks, spread their wings, and walk sideways to their opponent), as well as appeasement displays (begging calls with half extended wings and a lowered body). They use visual cues to track down bird and turtle nests in addition to using visual cues to forage.
There are no specific sources on the use of pheromones in fish crows but other birds do use pheromones to communicate. Fish crows are assumed to have a sense of smell, as other closely related crow species have a sense of smell. (Hardy, 1990; Laiolo and Rolando, 2003; McGowan, 2001; Zerega, 1880)
Fish crows are omnivores with highly varied food habits. These birds are generally observed stealing eggs from bird nests, and studies have observed these crows stealing shorebird eggs and turtle eggs (like Florida softshell turtles [Apalone ferox]). Some bird species preyed upon include white ibises (Eudocimus albus), Virginia rails (Rallus limicola), and common terns (Sterna hirundo). Santisteban et al. (2002) reported that visibility is a key factor in whether the crows prey upon a nest or not. They will also prey upon chicks, but will not actively hunt them down.
Fish crows also consume fish, crabs, and invertebrates usually found along the shoreline. Gorenzel et. al. (1994) observed fish crows preying upon fish grown in aquaculture facilities.
In agricultural areas, fish crows consume waste grain and ticks found on cattle. They will search for grubs in plowed fields. They will also hunt flying insects and spiders.
McGowan (2001) observed fish crows drinking nectar from a tiger's claw tree (Erynthia). They also consume fruit like mulberries (Morus) and seeds.
In urban areas, fish crows eat garbage and therefore search for food in dumpsters and at garbage dumps. Fish crows also consume carrion, and have been observed ingesting dead fish and birds. (Gorenzel, et al., 1994; Hamel, 1992; McGowan, 2001; Montevecchi, 1978; Santisteban, et al., 2002; Shields and Parnell, 1986)
Predation on fish crows commonly occurs during nesting season. Raccoons (Procyon lotor), rat snakes (Pantherophis), and eastern gray squirrels (Sciurus carolinensis) prey upon fish crow eggs. Owls, red-tailed hawks (Buteo jamaicensis), Cooper's hawks (Accipiter cooperii), broad-winged hawks (Buteo platypterus), and American kestrels (Falco sparverius) prey upon fish crow young and adults. McGowan (2001) states that humans (Homo sapiens) are a common nest predator.
Both male and female fish crows attempt to scare off predators through mobbing behaviors, such as swooping down at predators. They will also make warning calls. When an alarm call is sounded, fish crows flock together to mob predators. (McGowan, 2001)
Fish crows are nest predators and seed distributors (seeds have been found in their feces). Fish crows are eaten by predatory birds like American kestrels (Falco sparverius). Their young and eggs are preyed upon by squirrels and raccoons (Procyon lotor).
Fish crows are hosts to ectoparasites such as chewing lice (Myrsidea americana) and crow lice (Philopterus corvi). Dusek and Forrester (2002) observed several blood parasites affecting fish crows including protozoans that cause Avian Malaria (Haemoproteus danilewskii and Haemoproteus picae). They also observed the bacterium Plasmodium relictum, which causes Mycobacterium Avian Complex infections. Fish crows are also susceptible to West Nile Virus infections. (Dusek and Forrester, 2002; McGowan, 2001)
Humans benefit from fish crows in research and education fields, as they can be used to research how nest predators can find nests on which to prey (Santisteban et al., 2002). Fish crows are also used in West Nile virus research.
Historically, fish crows were popular with bird watchers. In Arkansas, people can hunt fish crows from September 1 through February 21 (on Mondays through Thursdays only) and there is no bag or possession limits for fish crows. They are hunted for sport, not food. (Hardy, 1990; McGowan, 2001; Reese, 2015; Santisteban, et al., 2002)
Gorenzel et al. (1994) report that fish crows are frequent pests at aquaculture facilities and have also been observed eating crops in rural areas. Fish crows can also transfer West Nile Virus to humans. (Gorenzel, et al., 1994; McGowan, 2001; Turell, et al., 2003)
Fish crows are listed as a species of "Least Concern" on the IUCN Red list, and their populations are growing. They are listed as protected from being hunted in most states by the United States Migratory Bird Treaty Act. They are not mentioned in the United States Federal list, CITES, or the State of Michigan list.
Threats to fish crows include hunting in some states (like Arkansas) where they are considered to be pests. Hunting is considered to be the number one cause of death in fish crows. In the early 2000s, there was an outbreak of West Nile Virus in fish crows, but their numbers have since recovered and increased since the outbreak.
While fish crows can be hunted, there are rules in place to protect populations as a whole. States are not to allow hunting during nesting season, hunting seasons are not to be longer than 124 days, and crows are only allowed to be killed using firearms, falconry, or through archery. States are allowed to set their own hunting seasons, bag limits, and possession limits. Due to the range expansion of fish crows, their populations are expected to continue growing. (Arkansas Game and Fishing Commission, 2019; Birdlife International, 2016; McGowan, 2001)
Rebecca Salen (author), Radford University, Lauren Burroughs (editor), Radford University, Logan Platt (editor), Radford University, Karen Powers (editor), Radford University, Galen Burrell (editor), Special Projects.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
uses sound to communicate
living in landscapes dominated by human agriculture.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
areas with salty water, usually in coastal marshes and estuaries.
an animal that mainly eats meat
flesh of dead animals.
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.
parental care is carried out by females
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
an animal that mainly eats fruit
an animal that mainly eats seeds
An animal that eats mainly plants or parts of plants.
An animal that eats mainly insects or spiders.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
parental care is carried out by males
marshes are wetland areas often dominated by grasses and reeds.
makes seasonal movements between breeding and wintering grounds
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats nectar from flowers
an animal that mainly eats all kinds of things, including plants and animals
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
an animal that mainly eats fish
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
an animal that mainly eats dead animals
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
living in residential areas on the outskirts of large cities or towns.
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
living in cities and large towns, landscapes dominated by human structures and activity.
uses sight to communicate
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