I hope they return. They were two drakes, two ducks and seemed to have paired off in the Summer. Then a week before their departure they engaged in some interesting ritualistic behaviors including the longest stretches of flying I'd seen from them as they went a hundred yards one way and then looped back toward the pool/pond where they lived and swooped low over it, the duck leading the drake. Then the drakes engaged in what looked like neck wrestling while the ducks looked on. When I returned to check on them a few days later one drake appeared to be shunned by the others who rested on the floating duck house while the "losing" drake walked the perimeter of the pool and quacked softly as if hesitant to get in the water. When I returned a few days after that to check on them they were all gone. On the one hand I was happy that being raised in those first few weeks by me they had, after about five months on their own at our abandoned pool, considerable "wild" instincts intact and could fly that well. On the other hand I will now worry for their safety vis a vis humans (hunters) during their travels and I will certainly be ecstatic if they return next Spring or Summer.
Will keep you posted and would love to hear from others on this site who've had "pet" ducks fly away, especially if they returned.