Midrash su Levitico 11:16

4) (Vayikra 11:15) ("Every raven after its kind") "raven": This is the (black) raven; "every raven": to include the "deep" (i.e., white) raven and the pigeon-headed raven; "after its kind" (lemino): the starling; "after its kind" (lemineihu, Vayikra 11:16): to include the swallow.

5) (Vayikra 11:16): "and the hawk after its kind": "the hawk": as indicated; "after its kind": to include bar charya. Why is "lemineihu" (after its kind) mentioned four times? For I might say that only these (birds that are mentioned) are forbidden, but the rest (that are not mentioned) are permitted; it is, therefore, stated "lemineihu" to include (the others of its kind that are not mentioned). How so? I deduce from what is mentioned, viz.:

6) Just as the nesher (Vayikra 11:13) which is mentioned, has no crop and does not have an additional claw (on the hind part of the leg) and has a craw which does not peel easily, and grasps (with its claws) and eats, so, all birds of this kind are unclean. Just as turtle-doves and young pigeons have a crop and have an additional claw and have a craw that peels easily and do not grasp (with their claws) and eat, so, all birds of this kind are clean.