Ravens are related to the crow, but show more intelligence and love to acquire shiny objects. The reason it is more intelligent than any other bird is because it can use a tool to open or break objects and can be trained to speak.
The raven is known in Native American lore as the trickster or creator, symbolizing a transformation. The raven has shape shifting qualities and was often called upon by medicine men to clarify visions, due to its ability to foretell the future, omens, and signs. Also known for its healing abilities, by exposing the truth beneath secrets that harm one's health and harmony.
In Celtic lore, the raven will do what they want, when they want and they'll tell you to "stow it" if you don't like it. The raven stands for individuality with a total disregard to what others think. Further, the crow is deeply honored by the Celts as an augury, or prophecy, oracle. The Celtic goddess, Morrigan, descended upon battlefields in the shape of a raven. Morrigan, in these forms of shimmery black winged legions, would consume the souls of fallen warriors in battle and carry their souls appropriate spiritual realms.