Bird lice are not lice!
That is, they do not belong to the bug order.
They belong to a small order by themselves, but they are parasites like
the lice.
The little white book lice that scurry away when we open an old book
that has been standing on the back shelf, are not lice, either; they
also belong to a little order of their own, and are constructed very
differently from the true lice.