We have had multiple trumpeter swan pairs on our lake and the 3 surrounding lakes for several years. This year we had pairs early on. Then we had a lone female show up with 5 cygnets that were very young. Then about 6/28/15 they all vanished. We seem to have a lot of Canada geese around. This is not usual for our lakes...could this be the problem? Also lots of fireworks on the surrounding lakes. Very sad not to see them. Any ideas?