The Crows and Jays (Corvidae) are a cosmopolitan family of 127 species, that contains the crows, ravens, rooks, jackdaws, jays, magpies, treepies, choughs and nutcrackers.

They are considered the most intelligent of the birds having demonstrated self-awareness in mirror tests and tool making ability — skills until recently regarded as solely the province of humans and a few other higher mammals. 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 tip of South America and the polar ice caps. The majority of the species are found in tropical South and Central America, southern Asia and Eurasia, with fewer than 10 species each in Africa, Australasia and North America.

The brain-to-body weight ratios of corvid brains are among the largest in birds, equal to that of great apes and cetaceans, and only slightly lower than a human. 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. Since most corvids are cooperative brooders, their young can learn from different members of the group. 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. A metaanalysis testing how often birds invented new ways to acquire food in the wild found corvids the most innovative birds. A 2004 review suggests that their cognitive abilities are on par with those of great apes.

New Caledonian Crows (Corvus moneduloides) are notable for their highly developed tool fabrication. They make angling tools of twigs and leaves trimmed into hooks, then use the hooks to pull insect larvae from tree holes. Tools are engineered according to task and apparently also to learned preference. Recent studies revealed abilities to solve complicated problems, which suggests high level of innovation of a complex nature.