The Mishna has a rule that birds which are do'reis aren't kosher (What does it mean to be do'reis? Rashi explains that it lifts it's prey with it's nails, Tosafos argues that even a chicken does that [rashash says he never saw a chicken do that], and therefore explains that it begins to eat prior to the prey being fully killed.
Tosafos wonders where this rule comes from. There are two possibilities. Either Chazal were zoologists and spent time searching all birds which are do'reis and found that every bird that is do'reis is tamei. It is doubtful that they would have invested so much time into doing the research to determine that there is no kosher bird at all that is do'reis. Another possibility is that they weren't disclosing a fact, rather a halacha that they had from Moshe - הלכה למשה מסיני, that any bird which is do'reis isn't kosher. The problem with the approach of being a halacha l'moshe mi'sinai is that it makes the pasuk of פרס or עזניה superfluous since one of the two is do'reis and therefore not kosher due to the halacha l'moshe misinai. See Maharatz Chiyus who discusses the possibility of something being a halacha l'moshe mi'sinai and supported by a pasuk as an אסמכת בעלמא. Tosafos concludes that it is not a halacha but rather a tradition from Noach who did all the research when he was gathering the birds for the teiva.
The Maharatz Chiyus raises and interesting point. Although we don't generally learn things from before matan torah, natural facts can be learned from before matan torah. Therefore, if we had a tradition from Noach that all do'reis birds are tamei, we would be able to use that as a source making any passuk unnecessary. Just as Tosafos assumes that if we had a halacha l'moshe misinai testifying that all do'reis birds are tamei, it would make the pasuk of peres or azniya extra, so too when we have a tradition from Noach to that fact, it should make the pasuk of peres or azniya extra?