Even as the ducklings grow they still run to mom to seek warmth at night, regardless of having their own feathers to keep them toasty, they prefer to sleep underneath moms wings. Which is a pretty funny sight when they are almost the size of their mother and 15 of them are still trying to huddle close to her, but the mothers are very tolerant of their now preteen ducklings still wanting to be coddled in their pre-adulthood stage.
This summer I was surprised with three mothers that sat one eggs, one presented me with 17 ducklings, one with 13 ducklings and the final one descended from her nest with 8 ducklings. Sadly, but not unexpectedly we did loose 5 total from the three batches, but the rest grew and are still growing. Many are black and white, some solid white, and some gray(blue) and white. Some have found new homes, because I am pretty sure I would go broke trying to feed all of them this winter, but I did keep some. They are full size now and some have broken off from their mother and go about their day hanging out with other young ducks, but there are still four that like to stay near their mothers, all of them are females and I am sure come spring they will venture away from their mother and sit on eggs of their own and emerge with 15 darling ducklings of their own!
If you are considering getting ducklings please consider Muscovy ducks, they are a treat to have around and provide entertainment for everyone as they waddle through the yard looking for slugs and bugs to top off their meal.