less intelligent I don't know - I think ducks are just le,ss domesticated...all of mine try it during most of the season!
I tried caging one like you said last year, Annie and she went ballistic and abandoned the nest.
She is sitting under the upturned lid of an old sandpit, which is rested against some glass and filled with water - she does not mind the others having a bath right above her - often very noisy! Awkward spot - if I change anything she will notice, so not stupid!:&>