Pics might be needed to get a true assessment of the issue here!


Spend TIME sitting still in their presence... down low, at their level. Move slowly.. bait yourself with some meal worms, laid near you and on your legs (or even chick feed) and keep your hands to yourself.. the pin feathers coming in can be painful if squeezed and you want them to have a good experience.
Try a little scrambled egg one time. New things often take a couple of introductions to realize how much they love something, so be patient. Please note I am a tightwad with treats but they can be useful at times.
How many ducks and chicks total? What are you feeding them? Are these your first birds? Do you know what breeds they are, as this can have major impact on flightiness. Are they indoor or outdoor brooder? 24 hour lighting or something more natural? Many things can effect behavior... including keeping the two species together... ducks were more scared than chicks in my experience. And once I thought I would never get a Leghorn chick again because of how their flightiness effected other chicks... but we adored her a ton! We just learned to handle the most freaked out one first to minimize the impact on others. Once the birds grew out, they all had their own individual personalities and made up their own mind how they feel about me..
Larger flocks and larger spaces are more difficult to achieve the close calmness in my experience. Smaller spaces can minimize chasing and maximize exposure. But if we show up for 3 or 5 minutes a few times a day we are literal strangers. How you approach them is important. Hovering from the top makes us like aerial predators. Spend longer periods of time like a half hour and you become part of the environment... talk to them in a low voice so they get used to hearing you. When I have mine indoors they are raised to waist level or higher and approach from the front.. let them get on you. They choose to approach, then slowly interact by waving a finger. When they make the choice it's different.
Most of mine get individual rides when being trained to return to the coop in the evening. The individual handling does seem to impact their confidence in me. Once they are old enough to roost.. approaching once they have roosted for the evening and calmed down while it's dim can also help.
Best wishes for your flock!
