Shiluach HaKen
A. The mitzvah of Shiluach HaKen should be performed at night, since then the mother is certainly present; during the day, sometimes the male is present and sometimes the female, and there is no mitzvah to send away the male. Since it is difficult to identify them, it should therefore be performed at night.
B. There is no need to declare the place of the nest ownerless, since nowadays in any case no one wants to acquire the eggs or chicks, and they are not acquired through the legal acquisition of one’s courtyard.
C. Rashi and the Rambam disagree as to whether one must actually take hold of the dove with one’s hands, or whether it is sufficient to cause it to be sent away in any manner. In practice, the halachah is ruled according to Rashi’s view, that one does not need to hold it in one’s hand.
D. At the time of sending it away, one should intend to fulfill the mitzvah through any means that will cause the dove to fly away from there, since sometimes the mother flees as soon as one approaches. If one intended to remove it by means of a stick or the like, he does not fulfill the mitzvah. Therefore, before approaching the nest, one should think that any cause by which the dove flies away — such as by opening a door or by his approaching the place — will be for the sake of the mitzvah.
E. One must lift the eggs and intend to acquire them, and afterward he may do with them as he wishes — return them to their place or discard them.
F. The mother must move away and not stand near the nest at the time that he lifts the eggs or chicks.
G. If one wishes to fulfill the mitzvah again, he may declare the eggs or chicks ownerless in the presence of three people (for example, he should go before three people and tell them that the eggs/chicks in such-and-such a place are ownerless), and when the mother returns, he may perform the mitzvah again.
H. One does not recite a blessing over Shiluach HaKen, but one should have intention at the time of the act to fulfill the mitzvah, as stated above.
I. There is no minimum amount of time for the mother to brood over the eggs; as long as there are eggs in the nest, one may fulfill the mitzvah of Shiluach HaKen with them.
It should be noted that according to Kabbalah, one should not perform the mitzvah of Shiluach HaKen during the days of Sefirat HaOmer; however, if this nest that he saw will not remain afterward and he will lose the mitzvah, he should perform it immediately.
Source
Shulchan Aruch, Yoreh De’ah, siman 292
