Q. Do you make a brocho on shiluach haken? If yes, which; "Al Shiluach Haken" or "al mitzvas shiluach haken?" Should he recite without the name of Hashem? Do you say shecheyanu?
A. Poskim disagree as to what is the correct bracha if any to be recited.
Many Poskim rule against the opinion of the Ra'aved (Tomim Deim 179), the Rokeach (366) and Aruch Hashulchan (292: 10), and maintain that no brocho should be said at all.
Various reasons are given why we do not recite a brocho. Meiri (Megila 21b) maintains that since one is not obliged to look for a nest and he complies with the mitzva when by chance he finds one, no blessing is to be recited.
Toras Nessanel (9) explains, that the eggs may be already spoiled, (or not there yet at all), so it is a doubtful brocho that we do not recite. Binyan Tzion (14) adds that if he recites, before he can actually send away the mother bird, she may just fly away herself and the blessing will be in vain.
Horav Shlomo Miller's Shlit'a opinion is similar and no brocho should be recited including Shecheyanu.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller Shlit'a