Crow facts for kids
Quick facts for kids Crow |
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| American crow (Corvus brachyrhynchos) | |
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Corvus
Linnaeus, 1758
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Crows (pronounced /ˈkroʊ/) form the genus Corvus in the family Corvidae. They are medium to large sized birds, carnivores and scavengers.
The genus includes the crow (carrion crow or hooded crow), the rook, jackdaw, and the large common raven. The genus has 40 or so members on all temperate continents except for South America, and some islands.
The Corvus makes up a third of the species in the Corvidae. Crows appear to have evolved in Asia from corvid stock which had evolved in Australia. The collective name for a group of crows is a flock or, more poetically, a murder.
Contents
Food and feeding
Crows are omnivorous. Their diet consists of invertebrates, nestlings, small mammals, berries, fruits, seeds, and carrion. They, however, have adapted well to human conditions, and have come to rely on human food sources.
In a US study of American crows around campgrounds and human settlements, crows appeared to have a very diverse diet, taking anthropogenic foods, such as: bread, spaghetti, fried potatoes, dog food, sandwiches, and livestock feed. The increase in available human food sources is a contributing factor to the rise in the population of crows.
Some crows also eat many agricultural pests, including cutworms, wireworms, grasshoppers, and harmful weeds.
Reproduction
The partner bond in crows is extremely strong, and even lifelong in some species. Males and females build large nests together in trees or on ledges. The male will also feed the female during incubation. The nests are constructed of a mass of bulky twigs lined with grass and bark. Crows can lay between 3 and 10 eggs, typically ranging between 4 and 7. The eggs are usually greenish in colour with brown blotches. Once hatched, the young remain in the nests for up to 6–10 weeks depending on the species.
Crows use several different forms of parental care, including bi-parental care and cooperative breeding. Cooperative breeding takes place when parents are helped in raising their offspring, usually by relatives, but also sometimes by non-related adults.
Interspecific communications
Facial expressions are the most widely used method to express emotions by humans. Based on the experimental subject of American Crows' behavioral changes to varying human gazes and facial expressions, Clucas et al. (2013) identified that crows are able to change their behaviors to the presence of direct human gaze, but did not respond differentially to human emotional facial expressions. They further suggested that the high intelligence of the crows enables them to adapt well to human-dominated environments.
Intelligence
Some crow species not only use tools but also make tools. New Caledonian crows (Corvus moneduloides) are notable for their highly developed tool fabrication. They make angling tools of twigs and leaves trimmed into hooks, and then subsequently use the hooks to pull insect larvae from tree holes. Tools are engineered according to task, and apparently, also to learned preferences. Recent studies revealed abilities to solve complicated problems, which suggested high levels of innovation of a complex nature. Researchers have discovered that New Caledonian crows don't just use single objects as tools—they can also construct novel compound tools through assemblage of otherwise non-functional elements. Great apes are the only other animals known to use tools in such a fashion.
Crows are now thought to be, with parrots, among the world's most intelligent birds. They have a brain size (adjusted for body size) as large as some apes.
One carrion crow was documented cracking nuts by placing them on a crosswalk, letting the passing cars crack the shell, waiting for the light to turn red, and then safely retrieving the contents. A group of crows in England took turns lifting garbage bin lids while their companions collected food.
Members of the corvid family have been known to watch other birds, remember where they hide their food, then return once the owner leaves. Crows also move their food around between hiding places to avoid thievery—but only if they have previously been thieves themselves (that is, they remember previous relevant social contexts, use their own experience of having been a thief to predict the behavior of a pilferer, and can determine the safest course to protect their caches from being pilfered). Studies to assess similar cognitive abilities in apes have been inconclusive.
The ability to hide food requires highly accurate spatial memories. Crows have been recorded to recall their food's hiding places up to nine months later. It is suggested that vertical landmarks (like trees) are used to remember locations.
Role in myth and culture
Folklore often represents crows as clever, and even mystical, animals. In many parts of Britain, gatherings of crows, or more often magpies, are counted using the divination rhyme: "one for sorrow, two for joy, three for a girl, four for a boy, five for silver, six for gold, seven for a secret never to be told." Another rhyme is: "one for sorrow, two for mirth, three for a funeral, four for a birth, five for heaven, six for hell, and seven for the Devil, his own sel."
Status and conservation
The survival and reproductive success of certain crows is assisted by their close relationship with humans.
Human development provides additional resources by clearing land, creating shrublands rich in berries and insects. When the cleared land naturally replenishes, crows use the young dense trees for nesting sites.
The American crow population of the United States has grown over the years. It is possible that the American crow, due to humans increasing suitable habitat, will cause Northwestern crows and fish crows to decline.
Species
- Corvus bennetti – Little crow (Australia)
- Corvus brachyrhynchos – American crow (United States, southern Canada, northern Mexico)
- Corvus cornix – Hooded crow (Northern and Eastern Europe and Northern Africa and Middle East)
- Corvus imparatus – Tamaulipas crow (Gulf of Mexico coast)
- Corvus leucognaphalus – White-necked crow (Haiti, Dominican Republic, Puerto Rico)
- Corvus macrorhynchos – Large-billed crow (Eastern Asia)
- Corvus nasicus – Cuban crow (Cuba, Isla de la Juventud, Grand Caicos Island)
- Corvus orru – Torresian crow or Australian crow (Australia, New Guinea and nearby islands)
- Corvus ossifragus – Fish crow (Southeastern U.S. coast)
Images for kids
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A carrion crow scavenging on a beach in Dorset, England.
