There are no less than 12 full grown swans (I think mute) on the lake in my backyard in Wakefield, Massachusetts. They appear to have dozens of babies with them. Could this be correct? The temp was about 12 degrees F. last night. We usually have swans, but only 4 or 5 and I don't remember winter swans. The lake is not yet fully frozen and they are swimming, etc. They seem fat and healthy. Could this be okay at this time of year?