Duck bites do hurt even though ducks have no teeth.
If a duck uses it's duck bill to bite you and is clamped down on your skin and you try to pull away then it can tear into your skin and cause your skin to hurt more.
They can also cause bleeding which happened to me when I was 3 and playing with some ducks at my Grandpas farm.
It was my fault though because when I was 3 I was out there agitating the ducks and so one finally came after me and bit me in the leg.
My mom also said that when I was 2 and still in diapers that one of the ducks grabbed my diaper and tore it and nearly ripped the diaper off.
The diaper I was wearing back then was the old thick plastic backed Pampers diapers.
My mom has a picture of me with my diaper half torn.
Now I try to teach my kids not to torment ducks when they are little because I have a 3 year old boy still in diapers and although it would be cute and funny to have his diaper torn off by a duck I'm not really wanting that to happen.
Duck bites do hurt so try to avoid getting bit by a duck.
Usually ducks are pretty friendly as long as you are friendly to them.
But kids usually do not know better and think they are just playing with them and the duck doesn't enjoy it.