Peacock in NZ?????? I hadn't heard that before!
I believe a peacock that was pushed by a line of beaters would be a challenging target, hell if we stopped shooting beautiful animals, the obese populations of Europe/America would be sweating even more than usual....
I believe that guinea fowl would be able to adapt to predators pretty well considering how well they manage in Africa, by roosting on trees at night. Make sure you get wild stock, as the degenerate types sold as pets are not likely to be as inclined to survive!