Hi, they look like they're doing well! A good idea for a brooder is a bathtub with a heat lamp on one end so if they get cold they can warm up as they don't have their mum. We used a bathtub as our brooder! We put tarp over it (except for the drain area) so they wouldn't slip over. We then put hay below the heat lamp, at the opposite end of the plug. Because ducks are so messy with their water we put their food and water near the drain so when they spilt their water it would run down. To clean we lifted the tarp and rinsed it.
Make sure the chick starter isn't medicated. If you can get duckling crumbles that would be better because it has the right amount of protein needed for ducks but if not I think you can use unmediated chick starter. For their water you can use a dish or lid. Ducklings love playing in their water so you could use a deeper container but make sure don't get stuck. You can let them swim in a kid pool or sink but always watch them and make sure they can get out. An old paint tray is good for water because it has a deep end and a shallow end.
You can give them small pieces of lettuce as a treat but not too much - It doesn't have a lot of nutritional value.
Another treat they love corn and peas, you can give this to them when they get bigger.
You can also give them kale, pak choy, watercress, berries, grapes, banana, cabbage.
Don't give them any avocado, citrus, nuts or salty food.
As they get older, move them onto duck grower and then a pellet for adult ducks.
Plastic kid pools work well for them to swim in, ducks need to be able to swim to keep their feathers in good condition and the water should also be deep enough for them to clean their beak.
The duckling with the bald patch on its side could just be moulting.
Good luck with your ducklings! Glad you saved them
