The cygnets will be just fine. The mother swan takes them out of the nest 24 hours after hatching to eat, bathe and preen. She usually will keep the cygnets in the nest for approximately 1-2 weeks at night. However, should the nest become submerged, mother swan will find higher safer ground or keep the young under her wings and on her back to keep them safe from predators, warm and dry. The Regal Swan