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Call of a Common Raven from the Yellowstone sound library.

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Corvus is a widely distributed genus of medium-sized to large birds in the family Corvidae. The genus includes species commonly known as crows, ravens and rooks; there is no consistent distinction between "crows" and "ravens", and these appellations have been assigned to different species chiefly on the basis of their size, crows generally being smaller than ravens.

The 45 or so members of this genus occur on all temperate continents except South America, and several islands. The crow genus makes up a third of the species in the family Corvidae. The members appear to have evolved in Asia from the corvid stock, which had evolved in Australia. The collective name for a group of crows is a "flock" or a "murder". The genus name is Latin for "crow".

Recent research has found some crow species capable of not only tool use, but also tool construction. Crows are now considered to be among the world's most intelligent animals with an encephalization quotient equal to that of many non-human primates. Along with intelligence, the article also foraging behaviour, as well as dieting, reproduction, lifespan and disease, and conservation status. Other factors associated with this genus of birds are also discussed.

Foraging

wolves and ravens associating near a body of water.

They have also been known to associate with other animals like coyotes and wolves. These associations are linked to feeding and hunting. Ravens use their calls to notify these animals when an injured prey is near. This interaction is most noticeable in winter where ravens are associated with wolf packs nearly 100% of the time. As a result of this connection, there have been studies conducted on the reaction of prey animals to the call of the raven. In areas where ravens associate with predators, prey animals are more likely to avoid predation by leaving after hearing the call. They are also capable of distinguishing between coyotes and wolves and have shown a preference for wolves. This may be due to the fact that wolves kill larger prey. When hunting, ravens can locate injured animals, like elk, and can call out to wolves to kill them. At times, ravens associate with wolves even when there is no carcass and can even be seen forming relationships with them. This includes playing with cubs, for example ravens may use sticks, pick at their tails, or fly around them.

Ravens have been mostly seen among travelling wolf packs rather than resting wolves, possibly due to the increased likelihood of food. They are also known to trust wolves in the pack they follow, when encountering a carcass killed by animals other than wolves they will be more apprehensive to eat from it. This symbiotic relationship between ravens and wolves is shown to be mutualistic, ravens help wolves find prey and when the wolves kill them the ravens can eat too. However, this relationship is not without its faults. Ravens may at times eat more of the prey than the wolf does. This problem has also been linked to wolf pack size, with some researchers suggesting that one of the reasons wolves hunt in larger packs is so that ravens (and other scavengers) get less of the food.Along with contention in wolves, other they can also bother each other. By feeding off of the same carcass it is possible that some ravens will steal from their conspecifics. This behaviour is related to the ravens ability to make quick decisions about eating the food then or storing it for later, dominance and fighting ability.

Intelligence

In the past there have been plenty of studies conducted on how ravens and corvids in general learn. Some of these studies have concluded that the brains of ravens and crows compare in relative size to great apes. The encephalization quotient (EQ), helps to expose the similarities between a great ape brain and a crow/raven brain. This includes cognitive ability. Even though the brain differs significantly between mammals and birds we can see larger forebrains in corvids than other birds (except some parrots), especially in areas associated with social learning, planning, decision making in humans and complex cognition in apes. They have also been known to use tools, and can recognize themselves in a mirror. This complex cognition can also be extended to socio-cognitive abilities. Studies have been conducted regarding the development and evolution of social abilities in ravens. These results help to show how ravens prefer to form stable relationships with siblings and close social partners as opposed to strangers. The development in social abilities is essential for raven survival, including identifying what poses whether something poses a threat and how ravens alert others nearby of an incoming threat.