I think that almost all swans migrate. Not sure if this one is at its winter destination or not. Rancho Blanco is a big ranch west of Helotes (and San Antonio) and we (that is, the local chapter of the Native Plant Society of Texas) were invited there by one of its owners to look at the plants around this lake and along a road nearby. If the lady that invited us had been there, we could have asked her questions about the swan and the ducks (those were on the other side of the lake, so couldn't get a decent pic). Unfortunately, she couldn't be there...I would've like to know also. I was told there might be future outings there, so maybe I can find out!