Cruelty to birds?

Have you ever been puzzled by the phrase, "killing two birds with one stone?" I mean, have you ever seen amyone kill bird with stones?
I suppose it makes more sense than one version I heard someone use, "killing two birds with two stones." Now that's seriously inefficient.

But times change, and we as modern human beings have to be sensitive to birds rights and feelings. Plus, we've got to tailor our old sayings to something kids can relate to. That's why I've begun to use the expression, "killing two pigs with one bird." Now that's progressive!