Be sure the blackbird isn't trapped and that you know for sure it's coming out (often they are trapped.) If you know for sure it's actually coming out then phone your pest control and get their advice. Often they rent cages out and you may just be able to lure it out with food and water. Good luck More I'd suggest, while you're waiting for the experts, try luring it out with light. Most birds hate darkness. Turn off all the lights, and block off any source of light except one open window. If all is quiet for a while (it might be a long while), the bird will likely come out on its own.