I don't think you can make ducks (or other usually wild birds) more friendly. Instinct is to strong. I raised 5 Mallard Ducklings in my house, with my cat making sure they didn't pull anything funny in the house. I handled them, talked to them and fed them by hand. They grew up, got feathers and stinky and had to go OUT to the pond. They never came near me again. Well, "near" is relative. They never let me touch them again. They would come within 3 feet of me to eat the food I brought them, But if I moved closer to them, they ran away.
My daughter went to school in Boston. When I went to visit we would feed the ducks in Boston Gardens. It is a cement pond, so there is very little vegetation for them to eat, so they counted on the hand outs people brought. I brought cracked corn, since white bread isn't fit food for animals. (humans either IMHO) The Boston ducks who were raised by Mama Boston Garden Ducks would eat the corn off our feet, if we dropped it there, but if our foot moved they were GONE in a second.
I wish that you could make them more friendly, but it doesn't seem to be the case. The survival instinct is just too strong.
