The Lightning Bird is widely feared as a witch's familiar, it's considered an evil creature because it does the bidding of witches, if a Witchdoctor dispatches an Impundulu it can cause illness and bad luck to a person.
It can cause illness and bad luck to a person. This was what it's considered an evil creature. It does the bidding of witches. A Witchdoctor dispatches an Impundulu.