Swan in Bourton

This beautiful bird has appeared on a small side stream of the River Windrush in Bourton. It is on its own and appears healthy but I am puzzled as to why it has suddenly appeared. It has been there for a week now, it's legs look strong and it ran along the water this morning but did not actually take off (see extra). Hmmmmm. 
(the orange reflection is from the dogwoods)