Not just true of crows. I volunteer at a raptor conservation organisation in the UK. Many of the birds (eagles, vultures, owls, etc) recognise several people, e

Not just true of crows. I volunteer at a raptor conservation organisation in the UK. Many of the birds (eagles, vultures, owls, etc) recognise several people, especially those that fed them when they were being trained. They demonstrate this in the free-flying displays (where they could in principle just fly off if they wanted to) by routinely returning to the keeper, sometimes after flights where they travel some distance from the display area. They are also good at recognising and responding to signals, especially those that indicate a food treat may be forthcoming. In some cases the birds dislike specific individuals and will not work with them in a display.