Zevachim 69B

רבי יהודה אומר: מטמא.

R' Yehuda says: Its status is like any other carcass of an unslaughtered kosher bird, and its meat renders one who swallows it ritually impure.

אמר רבי מאיר: קל וחומר; אם נבלת בהמה, שמטמאה במגע ובמשא ⁠– שחיטתה מטהרת טריפתה מטומאתה; נבלת העוף, שאינו מטמא במגע ובמשא ⁠– אינו דין שתהא שחיטתו מטהרת טריפתו מטומאתו?!

R' Meir said: My opinion can be inferred a fortiori. If an animal carcass transmits impurity to a person through touching it and through carrying it, and nevertheless the slaughter of an animal purifies it, even if it is a tereifa, from its impurity, i.e., its slaughter prevents it from assuming the impurity status of a carcass, then with regard to a bird carcass, which possesses a lesser degree of impurity, as it does not transmit impurity to a person through touching it and through carrying it, but only through swallowing it, is it not logical that its slaughter should purify it, even if it is a tereifa, from its impurity?

מה מצינו בשחיטתו ⁠– שהיא מכשרתה לאכילה, ומטהרת טריפתו מטומאתו; אף מליקתו, שהיא מכשרתו באכילה ⁠– תטהר טריפתו מידי טומאתו!

And once it is established that slaughter renders a bird that is a tereifa pure, it can be inferred that just as we found with regard to its slaughter that it renders a bird fit for consumption and purifies a bird, even if it is a tereifa, from its impurity, so too its pinching, which renders a bird offering fit with regard to consumption, should purify it, even if it is a tereifa, from its impurity.

רבי יוסי אומר: דיה כנבלת בהמה ⁠– שחיטתה מטהרתה, ולא מליקתה.

R' Yosei says: Although one can derive from the case of an animal that slaughter renders even a bird that is a tereifa pure, that derivation cannot be extended to pinching. The same restriction that applies to every a fortiori inference, namely, that a halakha derived by means of an a fortiori inference is no more stringent than the source from which it is derived, applies here: It is sufficient for the halakhic status of the carcass of a bird that is a tereifa to be like that of the carcass of an animal that is a tereifa; its slaughter renders it pure, but its pinching does not.