Torah Temimah cites Toras Kohanim (Sifra, Vayikra Dibbura DeChovah, Section 10).
Sefaria — Toras Kohanim (Sifra, Vayikra Dibbura DeChovah, Section 10)
“And he shall bring them” — them themselves: birds have no redemption. “To the Kohen” — the owner is obligated to arrange their delivery.
Diyuk of “otam” and “el ha-kohen” — birds have no redemption; the owner must arrange their arrival.
Unlike some animal offerings that can be redeemed, the bird chatas and olah must be the actual birds placed in the Kohen’s hands. The owner is responsible for the practical logistics of bringing them; he cannot simply transfer the monetary value.