We have been hearing this same scenario in various areas. The extreme temperatures, swans and other birds getting caught in the strong winds prior to and after the migratory time periods, getting blown off course and catching cold, drowning or starving are the possibilities. Hopefully, as the temperatures warm and young birds are chased from areas that are inhabited by older pairs, swans will appear back on your lake. As long as there is adequate food resources, shelter from inclement weather and predators, then it is just a matter of time that swans and other waterfowl will once again enjoy your lake. The Regal Swan