Crows were an Earth species of bird, described by the Fifth Doctor as "harbingers of doom". While crows were scavengers by nature, feeding on fresh meat such as roadkill killed by others, they did occasionally kill by themselves, although this usually only extended to field mice. (AUDIO: Plague of the Daleks, TV: The Day of the Clown)
According to Mr Middlewitch, crows originated from the time vortex, but the war between the Time Lords and Morbius scared them into fleeing their domain, and they took up residence on many planets, including Earth. (AUDIO: Morbius)
The Twelfth Doctor claimed that crows were able to talk to humans, but they eventually ceased this when humans stopped having intelligent conversations with them. In the 2nd century, crows were capable of repeating phrases as well as a few words, such as "Doc-tor" or "Monst-er". When Kar sacrificed herself to be a keeper of the gate, her brother Ban told the crows her name. As a result, the cawing sounds that became well known in the following centuries originated out of remembrance of Kar. (TV: The Eaters of Light)
In Gaul 641, crows were among those resurrected to carry out death as commanded by the Tenctrama during Attila the Hun's invasion of the Roman Empire. (PROSE: Combat Magicks)
After the 1240 sacking of Kiev, crows scavenged the remains of the dead. (PROSE: Bunker Soldiers)
In 1890, Vincent van Gogh painted crows soaring through the sky above a wheat field; this was one of his final paintings. (TV: Vincent and the Doctor)
A group of artificial Dalek-controlled crows mysteriously observed the Fifth Doctor and Nyssa when they arrived in 45th century Stockbridge. (AUDIO: Plague of the Daleks)
There were crows on the planet Querkus, which was once invaded by the Daleks. (PROSE: Roots of Evil)