Sending away the mother bird does not apply to sacrifices. However, how could this case occur? If one consecrated birds that are his, he was never obligated to send away their mother, because he needs to find the birds by chance. And if he found them and consecrated, they do not become consecrated, because they do not belong to him! Should we say that he lifted the chicks and consecrated them, then returned them to the nest? Then again he is not obligated to send away the mother bird.
Rav said, “The case is where he consecrated the birds, but they flew away, and he found them,” and Shmuel said “He consecrated his hen as money for the Temple, and it flew away and nested elsewhere.” It is understandable why Shmuel does not agree to Rav, because Shmuel’s explanation is wider in scope, but why does Rav not agree to Shmuel? Rav will say that when a hen flies away, its monetary sanctity disappears. And Shmuel? He will answer that the hen is still consecrated in the wild, because “To God belong the earth and its fullness.”
Art: Bela Spanyi - Flock Of Birds At Sunset