Lone swan

We managed a slow walk up to Bob's pond  once it had stopped raining although we still had a shower as we walked. Slowly as my knee is still not quite right and I had forgotten to wear a support bandage on it but thought it would be alright. Just about okay.
The swan is on it's own now as something happened to it's partner back in late March early April. It was found dead but no one seems to know what caused it. We were told that there was also a nest but if there were eggs we don't know. Bit of a mystery as a Canada goose also died which seems a bit too much of a coincidence. 
The swan always comes to see us but there seems to be a forlorn air about it which does sadden us. Do they mate for life? I'm sure they do so not sure if there is another lonely swan somewhere for it.
Tried black and white but not too sure if it worked. Oops, heavy rain shower hitting against the windows as I'm typing.