(Devarim 14:11) "Every clean bird you may eat": Because it is written (Vayikra 14:4) "And the Cohein shall command, and he shall take for the one to be cleansed (from leprosy) two birds," I might think that just as the slaughtered bird is forbidden (to be eaten), so, the sent-away bird; it is, therefore, written "Every clean bird you may eat (including the sent-away bird).
— But perhaps, just as the sent-away bird is permitted, so, the slaughtered bird is permitted; it is, therefore, written (Devarim, Ibid. 12) "And this is what you may not eat of them" (including the slaughtered bird.)
(Ibid.) "the great vulture, the bearded vulture, and the osprey": R. Akiva says: It is written here "nesher" (great vulture), and, elsewhere (Vayikra 11:13) "nesher." Just as there, all relating to nesher, both feeding and eating, is forbidden, so, here.
R. Shimon says: It is written here (Devarim, Ibid. 13) "the ayah," and there (Vayikra, Ibid. 14) "the ayah." Just as here, "the ra'ah" is understood as a kind of ayah, so, there.