here's what I do
1. lay a bed of celery in the bottom of your roasting dish
2. Turn your oven as high as it will go, mine goes to 550
3. salt and pepper your ducks to your liking, put some fresh herbs and sliced up citrus in the cavity and coat with an oil (I like bacon fat best, olive oil next) Let the birds reach room temperature, about 30 minutes usually while the oven is warming up
4. place the ducks on top of the celery they are resting in their own juices.
5. 18 -20 minutes for big ducks,; 13-16 for teal and small ducks
6. Remove from oven, and let the damn birds sit for at least 5 minutes
They will be medium rare and its a crime if over done, so dont over cook them.
Meanwhile, the juices in the bottom of your pan make a wonderful gravy. Add 2 tablespoons of Worcestershire sauce, the juice of a lemon, and a cup or port or red wine. Use some flour to thicken if need be.