Swans can tolerate very low temperatures due to the thickness of their feathers and down. If the lake is not totally frozen and the swans can still feed, then they may be getting adequate food. However, if the pond is completely frozen, then this might be a case of neglect , although there still could be some type of feeding system that does not warrant daily care. If you are still concerned, call your local Animal Control, a rehabilitative wildlife center, an animal shelter, your local newspaper or your wildlife commission. Even if the swans are considered exotic wildlife, there is still the need to render humane veterinary medical care, supplemental food and other care. Good luck. Please let us know how this situation is resolved. The Regal Swan