Never heard of sugar water. I just got two ducklings less than a week ago (one is a Rouen, the other is a Cayuga. I also have a two year old pekin). I keep their bin fresh with wood shavings, they ALWAYS have water and food, and I play with them each day for about an hour. Also,at night I keep...
Do you have a heat lamp for them? My brothers chicken died because of a lack of heat, so maybe your little guy just needs to be warm. Also, ducklings always need a lot of water, so make sure it has water regularly.
I have Rouen duckling that also has feathers on its feet. I'm not sure if it is a girl or a boy yet, but on both of its feet it has feathers. The feathers are on the outer toe of the feet, and I don't know what it means