Corvidae is a cosmopolitan family of oscine passerine birds that contains the crows, ravens, rooks, magpies, jackdaws, jays, treepies, choughs, and nutcrackers. In colloquial English, they are known as the crow family or corvids. Currently, 135 species are included in this family. The genus Corvus containing 47 species makes up over a third of the entire family. Corvids (ravens) are the largest passerines.

Corvids display remarkable intelligence for animals of their size, and are among the most intelligent birds thus far studied. Specifically, members of the family have demonstrated self-awareness in mirror tests (Eurasian magpies) and tool-making ability (e.g. crows and rooks), skills which until recently were thought to be possessed only by humans and a few other higher mammals. Their total brain-to-body mass ratio is equal to that of non-human great apes and cetaceans, and only slightly lower than that of humans.

Jerison (1973) has suggested that the degree of brain encephalization (the ratio of brain size to body size, EQ) may correlate with an animal's intelligence and cognitive skills. Corvids and psittacids have higher EQ than other bird families, similar to that of the apes. Among the Corvidae, ravens possess the largest brain to body size ratio. In addition to the high EQ, the Corvid's intelligence is boosted by their living environment. Firstly, Corvids are found in some of the harshest environments on Earth, where surviving requires higher intelligence and better adaptations. Secondly, most of the Corvids are omnivorous, suggesting that they are exposed to more different stimuli and environments. Furthermore, many corvid species live in a large family group, and demonstrate high social complexities.

Their intelligence is boosted by the long growing period of the young. By remaining with the parents, the young have more opportunities to learn necessary skills.

When compared to dogs and cats in an experiment testing the ability to seek out food according to three-dimensional clues, corvids out-performed the mammals.[36] A meta-analysis testing how often birds invented new ways to acquire food in the wild found corvids to be the most innovative birds. A 2004 review suggested that their cognitive abilities are on par with those of non-human great apes.[38] Despite structural differences, the brains of corvids and great apes both evolved the ability to make geometrical measurements.

They are medium to large in size, with strong feet and bills, rictal bristles, and a single moult each year (most passerines moult twice). Corvids are found worldwide, except for the southern tip of South America and the polar ice caps.[3] The majority of the species are found in tropical South and Central America and in southern Asia, with fewer than 10 species each in Africa and Australasia. The genus Corvus has re-entered Australia in relatively recent geological prehistory, with five species and one subspecies there. Several species of raven have reached oceanic islands, and some of these species are now highly threatened with extinction, or have already become extinct.

Some corvids have strong organization and community groups. Jackdaws, for example, have a strong social hierarchy, and are facultatively colonial during breeding. Providing mutual aid has also been recorded within many of the corvid species.

Young corvids have been known to play and take part in elaborate social games. Documented group games follow "king of the mountain" or "follow the leader" patterns. Other play involves the manipulation, passing, and balancing of sticks. Corvids also take part in other activities, such as sliding down smooth surfaces. These games are understood to play a large role in the adaptive and survival ability of the birds.

Mate selection is quite complex, and accompanied with much social play in the Corvidae. Youngsters of social corvid species undergo a series of tests, including aerobatic feats, before being accepted as a mate by the opposite sex.

Some corvids can be aggressive. Blue jays, for example, are well known to attack anything that threatens their nest. Crows have been known to attack dogs, cats, ravens, and birds of prey. Most of the time, these assaults take place as a distraction long enough to allow an opportunity for stealing food.

The below images are linked to galleries of my Corvid species seen and documented around the world, some 50 out of 135 species in the group.