I just got my first ducklings from Holderread's and this is on their Tip Sheet:
3. As you take the birds from the box and place them in the prewarmed brooding area, immediately dip each of their bills in the waterer to make sure that they drink promptly. Initially give lukewarm water with 1 tsp. honey or corn syrup per quart and chopped greens (described in #6). Do not give feed for as least an hour after giving birds water and greens. Thereafter, we recommend adding a water-soluble vitamin mix formulatedfor baby poultry to the water for the first 5 to 7 days. Because waterfowl drink more than twice as much water as chickens, use vitamin mixes at 1/2 the recommended rate for baby chicks. Never use REN-O SAL on ducks and geese.
Green feed (lettuce, spinach, tender young grass, etc.) chopped to 1/4-inch lengths and sprinkled in the water and on the feed helps get goslings as well as ducklings to eat quickly, and off to a fast start. 7. The correct brooding temperature is 90-92° F the first 3 days and 85-90° F for days 4 t07. Thereafter, drop the brooding temperature approximately 5° F per week. Birds must always be able to get away from the heat source to avoid the damaging effects of overheating.
Good luck!