If we don't need the birds' eggs, as they used to, why do we send a mother bird away from her own eggs just to fulfill the mitzvah of Sheluach HaKan? Would the mitzvah even apply if we are doing it just for the sake of the mitzvah and not actually for the eggs? Or would it be more along the lines of "if you need the eggs, then send the mother bird away"?
On that note, if we are going to do the mitzvah still these days, should/do we put the eggs back after we send the bird away and remove the eggs for a little while? Or does that somehow nullify the mitzvah?