Part of their success as a species is due to their omnivorous diet; they are extremely versatile and opportunistic in finding sources of nutrition, feeding on carrion, insects, cereal grains, berries, fruit, small animals, nesting birds, and food waste.

[24] One explanation for these genetic findings is that common ravens settled in California at least two million years ago and became separated from their relatives in Europe and Asia during a glacial period.

Other members of the Holarctic clade arrived later in a separate migration from Asia, perhaps at the same time as humans and wolves about 15,000 years ago.

[13][25] A 2011 study suggested that there are no restrictions on gene flow between the Californian and Holarctic common raven groups, and that the lineages can remerge, effectively reversing a potential speciation.

Its very wide and complex vocabulary includes a high, knocking toc-toc-toc, a dry, grating kraa, a low guttural rattle and some calls of an almost musical nature.

[50][53] The population sometimes known as the 'Punjab raven', part of the subspecies Corvus corax laurencei (sometimes misnamed C. c. subcorax[19][15]) occurs in the Sindh district of Pakistan and adjoining regions of northwestern India.

In his 1950 work, Grønlands Fugle [Birds of Greenland], noted ornithologist Finn Salomonsen indicated that common ravens did not overwinter in the Arctic.

[58] In the United Kingdom, the range is currently increasing after improved legal protection, but illegal persecution by gamekeepers remains a problem in many areas.

[61] Most common ravens prefer wooded areas with large expanses of open land nearby, or coastal regions for their nesting sites and feeding grounds.

In some areas of dense human population, such as California in the United States, they take advantage of a plentiful food supply and have seen a surge in their numbers.

[63] Common ravens are often located in coastal regions because these areas provide easy access to water and a variety of food sources.

[66][67][68][69] Ravens wary around novel carrion sites, and in North America, have been recorded waiting for the presence of American crows and blue jays before approaching to eat.

In Pakistan, egg-laying takes place in December,[50] but in north Africa (subspecies C. c. tingitanus), later than in Europe, in late March or early April.

The longest known lifespan of a ringed wild common raven was 23 years, 3 months,[81] which among passerines only is surpassed by a few Australian species such as the satin bowerbird.

With large-bodied carrion, which they are not equipped to tear through as well as birds such as the much larger and hook-billed vultures, they must wait for the prey to be torn open by another predator or flayed by other means.

[91] In contrast, a 1984–1986 study of common raven diet in an agricultural region of southwestern Idaho found that cereal grains were the principal constituent of pellets, though small mammals, grasshoppers, cattle carrion and birds were also eaten.

[95] Linguist Derek Bickerton, building on the work of biologist Bernd Heinrich, has argued that 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.

[96] One experiment designed to evaluate insight and problem-solving ability involved a piece of meat attached to a string hanging from a perch.

Four of five common ravens eventually succeeded, and "the transition from no success (ignoring the food or merely yanking at the string) to constant reliable access (pulling up the meat) occurred with no demonstrable trial-and-error learning."

Many of the feats of common ravens were formerly argued to be stereotyped innate behaviour, but it now has been established that their aptitudes for solving problems individually and learning from each other reflect a flexible capacity for intelligent insight unusual among non-human animals.

[103] Other research indicates that juveniles are deeply curious about all new things, and that common ravens retain an attraction to bright, round objects based on their similarity to bird eggs.

Common ravens can cause damage to crops, such as nuts and grain, or can harm livestock, particularly by killing young goat kids, lambs and calves.

[112] In the western Mojave Desert, human settlement and land development have led to an estimated 16-fold increase in the common raven population over 25 years.

Towns, landfills, sewage treatment plants and artificial ponds create sources of food and water for scavenging birds.

[62] Plans to control the population have included shooting and trapping birds, as well as contacting landfill operators to ask that they reduce the amount of exposed garbage.

[114] Culling has taken place to a limited extent in Alaska, where the population increase in common ravens is threatening the vulnerable Steller's eider (Polysticta stelleri).

[117] Across its range in the Northern Hemisphere, and throughout human history, the common raven has been a powerful symbol and a popular subject of mythology and folklore.

In some Western traditions, ravens have long been considered to be birds of ill omen, death and evil in general, in part because of the negative symbolism of their all-black plumage and the eating of carrion.

In Danish folklore, valravne that ate a king's heart gained human knowledge, could perform great malicious acts, could lead people astray, had superhuman powers, and were "terrible animals".

Additionally among the Norse, raven banner standards were carried by such figures as the Jarls of Orkney,[128] King Cnut the Great of England, Norway and Denmark,[129] and Harald Hardrada.