Poultry like chicken and turkey is best cooked at LOW heat on your grill. You definitely want to use a meat thermometer for large birds to test for doneness. Smaller birds are done when no pink juices appear when the meat is pricked. In whole birds, doneness can be checked when the leg joints turn loosely in their sockets.
If you’re a seasoned grillmaster, you can try for that golden brown effect by coating the skin with butter or a high heat oil like canola oil and starting your cooking at a medium-high temperature for about 20 minutes. Then finish the bird on a low heat setting.