The "snow birds" are here in Sarasota for the Winter. They come down from swamps and wooded ponds of the northern half of the United States and southern Canada. Mergansers are occasionally seen on Sarasota Bay. The visitors pictured were cruising in The Meadows Community pond. Check out the Celery Fields for a possible sighting.
The single bird above is a male. He is seen with 2 females in the top photo.