More innocent animals killed for what?

Leviticus 14:3 says, “And the priest shall go forth out of the camp; and the priest shall look, and, behold, if the plague of leprosy be healed in the leper;

14:4 Then shall the priest command to take for him that is to be cleansed two birds alive and clean, and cedar wood, and scarlet, and hyssop:

14:5 And the priest shall command that one of the birds be killed in an earthen vessel over running water:”  I knew god would want something killed if the leper lived.  Leviticus 14:6 “As for the living bird, he shall take it, and the cedar wood, and the scarlet, and the hyssop, and shall dip them and the living bird in the blood of the bird that was killed over the running water:

14:7 And he shall sprinkle upon him that is to be cleansed from the leprosy seven times, and shall pronounce him clean, and shall let the living bird loose into the open field.”  Why all this after the plague is healed?  Why is there need for the constant sprinkling of blood?  What could this possibly do?