Rowly, your new ducks are quite hardy but will need some attention for a while. It is recommended that you suspend a heat lamp about 18" above the floor of their pen, they will find the most comfortable temp on their own. You can start raising the lamp after about 4 or 5 days (I prefer a red bulb and should always have a spare). You should avoid drafts as much as possible You should have some bedding - I use pine shavings that I get from the local farm supply. Feed should be non medicated, broiler finisher works well if you are not going to use one of the commercial game bird starters, besides it is a lot cheaper. You should also add some pigeon grit to the food, they need that to aid digestion. They need a lot of drinking water! You will be amazed at how much, so while a small waterer will work for about 2 weeks, you will need a 4 or 5 gallon waterer. The ducklings grow very fast and need a fair amount of room to keep them calm, by 2 weeks they should have at least 2 sq ft each. I have a brooding pen in a garage and leave the door open during the day after the first week to begin hardening them off, they still can go under the heat lamp if necessary. They should develop most of their first feathers by 4 weeks, which is when I move them to an outdoor pen that has a small duck house. Baby feathers are not waterproof since there is no mother to rub oil on them, so avoid getting them wet. Mosts ducks are essentially full grown at about 8 weeks. Once they are outside and have their first feathers, they will enjoy pans of water and will forage actively in their area. I close them up at night to avoid possible predators. I continue to give my ducks cracked corn as adults, they love it as a snack and it keeps them bonded to me so I can keep track of how many I have. Putting them in the big pond will probably be quite traumatic for them. They may be afraid of the water and will probably stay close together. They will get over it but it can be a chore. Maybe releasing them on your island is an idea, I don't have that option. Since you don't have any mature ducks, they will have to learn on their own. A downside of having mature drakes is that they immediately rape all of the new hens - not a pretty site but everyone seems to survive it. I havn't got any experience with Muscovys, so I don't know how likely it is that they will stay. One thing I thing you will notice however is more wild ducks. Your natural decoys work really well. Hope this helps, ask on if I have missed anything important.
