In many, if not most, cases where we fulfill a positive commandment Chazal instituted a blessing (B'rachah) over fulfilling that command.
Looking through Shulchan Aruch Yoreh Deah 292, and other discussions of the commandment to send away the mother bird prior to taking her eggs/chicks, I do not see any mention of a blessing over this command.
Is there such a blessing (did I just overlook it?), and if not, why not?