Vultures were scavenger birds that feed on the dead carcasses of animals, and were regarded as dumb beasts in the world of Narnia.
The vultures sided with the White Witch to destroy Aslan. These "dumb" yet unpleasant creatures were spies that delivered information to the Witch and her army. At Aslan's Sacrifice, they circled the stone table, squawking with joy. They were seen flying off with giant bats along with the rest of the army afterwards.