I know it is said swans mate for life (typically); when we moved to a new office location there were 3 trumpeter swans living in the river next to our building; when summer came 1 left (we assume in search of a mate) and never returned. The other pair has been around for a year now. This morning I noticed only one is in the vicinity for the entire day and the one left here seems to be almost searching and calling continuously (for the other?). My question is, could the pair (or the original 3) have maybe been all females, or all males, hanging out together, and slowly they've left the group to find mates? Or is it unheard of that swans of the same sex hang together for an extended period of time?