Raven Corvus Corax

The common raven (Corvus corax), also known as the northern raven, is a large all-black passerine bird. Found across the Northern Hemisphere, it is the most widely distributed of all corvids. There are at least eight subspecies with little variation in appearance. It is one of the largest and heaviest, averaging 25 inches in length and 2.6 pounds in mass. Common ravens can live up to 21 years in the wild. Young birds may travel in flocks but later mate for life, with each mated pair defending a territory.
Corvus corax has an omnivorous diet and is opportunistic in finding sources of nutrition, feeding on carrion, insects, cereal grains, berries, fruit, small animals, and food waste. Uncommonly intelligent creatures, ravens have over the centuries been the subject of mythology, folklore, art, and literature. In many cultures, including the indigenous cultures of Scandinavia, ancient Ireland and Wales, Bhutan, the northwest coast of North America, and Siberia and northeast Asia, the common raven has been revered as a spiritual figure or god.
Apart from its greater size, the common raven differs from its cousins, the crows, by having a more sizeable and heavier black beak, large and slightly curved, with a culmen length of 2.2 to 3.3 inches, easily one of the largest bills amongst passerines. It has shaggy feathers around the throat and above the beak, and a wedge-shaped longish, strongly graduated tail, at 7.9 to 10.4 inches, and mostly black iridescent plumage, and a dark brown iris.
Flying ravens are distinguished from crows by their tail shape, larger wing area, and more stable soaring style, which generally involves less wing flapping. Despite their bulk, ravens are easily as agile in flight as their smaller cousins. In flight the feathers produce a creaking sound that has been likened to the rustle of silk. The voice of ravens is also quite distinct, its usual call being a deep croak of a much more sonorous quality than a crow’s call. Ravens can mimic sounds from their environment, including human speech. Non-vocal sounds produced by the common raven include wing whistles and bill snapping.
Common ravens can thrive in varied climates; indeed this species has the largest range of any member of the genus.
Relationships between common ravens are often quarrelsome, yet they demonstrate considerable devotion to their families.
Ravens are regular predators at bird nests, brazenly picking off eggs, nestlings and sometimes adult birds when they spot an opportunity. They are considered perhaps the primary natural threat to the nesting success of the critically endangered California condor, since they readily take condor eggs and are very common in the areas where the species is being re-introduced
Juvenile ravens call other ravens to a food bonanza, usually a carcass, with a series of loud yells.
Because of their size and defensive abilities, common ravens have few natural predators, but its eggs can be vulnerable to owls, martens, and sometimes eagles. Ravens are vigorous in defending their young and are usually successful at driving off perceived threats. They use their large bills in attacking potential predators. Humans are occasionally attacked if they get close to a raven nest, though serious injuries are unlikely. Their attackers in America have reportedly included great horned owls, northern goshawks, bald eagles, golden eagles and red-tailed hawks. Rarely, large mammalian predators such as lynxes, coyotes and cougars have attacked ravens. This principally occurs at a nest site and when other prey for the carnivores are scarce.
Juveniles begin to court at a very early age, but may not bond for another two or three years. Aerial acrobatics, demonstrations of intelligence, and ability to provide food are key behaviors of courting. Once paired, they tend to nest together for life, usually in the same location. Instances of non-monogamy have been observed in common ravens, by males visiting a female’s nest when her mate is away.
Breeding pairs must have a territory of their own before they begin nest-building and reproduction, and thus aggressively defend a territory and its food resources. The nest is a deep bowl made of large sticks and twigs, bound with an inner layer of roots, mud, and bark and lined with a softer material, such as deer fur. The nest is usually placed in a large tree or on a cliff ledge, or less frequently in old buildings or utility poles. Females lay between three to seven pale bluish-green, brown-blotched eggs. Incubation is about 18 to 21 days, by the female only. However, the male may stand or crouch over the young, sheltering but not actually brooding them. Young fledge at 35 to 42 days, and are fed by both parents. They stay with their parents for another six months after fledging.
In most of their range, egg laying begins in late February. Adults have been observed dropping stones on potential predators that venture close to their nests.
Common ravens can be very long-lived, especially in captive or protected conditions; individuals at the Tower of London have lived for more than 40 years. Lifespans in the wild are considerably shorter at typically 10 to 15 years. Ravens are intelligent creatures, capable of complex decisions. They demonstrate situational awareness. The brains of common ravens are the largest of any bird species. Specifically, their hyperpallium is large, for a bird. They display ability in problem-solving, imitation and insight.
Linguist Derek Bickerton and biologist Bernd Heinrich believe ravens are one of only four known animals (the others being bees, ants, and humans) who have demonstrated displacement, the capacity to communicate about objects or events that are distant in space or time from the communication.
An experiment to evaluate the insight and problem-solving ability of Ravens involved dangling a piece of meat attached to a string from a perch. To reach the food, the bird needed to stand on the perch, pull the string up a little at a time, and step on the loops to gradually shorten the string. Four of five common ravens eventually succeeded, using little or no trial and error. It has been established that Ravens have an aptitudes for solving problems individually and learning from each other, an intelligence unusual among non-human animals.
Another experiment proved that some could intentionally deceive other cretures. Ravens have been observed calling wolves to the site of dead animals, inducing the wolves to open the carcass, leaving the scraps more accessible to the birds. They watch where other ravens bury their food and remember the locations of each other’s food caches, so they can steal from them. Some ravens have also been observed pretending to make a cache without actually depositing the food, presumably to confuse onlookers.
Juvenile ravens are playful, having been observed sliding down snowbanks, apparently purely for fun. They engage in games with other species, such as playing catch-me-if-you-can with wolves, otters and dogs.

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