Because of their size, they are easy-to-find. They are easily the largest birds found in the game. The type of vulture seen in the game is based off the lappet-faced vulture, an old world vulture found in Africa, and some of South West Asia.
Several vultures will often appear over the site of a violent battle to consume corpses. Sharpshooter Rank 9 requires the player to shoot six animals in one dead eye burst, which can easily be done on a pack of vultures after completing a gang hideout.
Vultures are the only actual birds that make an appearance in the Undead NightmareDLC, however they cannot be looted. They can sometimes be seen flying over settlements and can also be seen flying during certain missions.