When I went down to the field this afternoon, a buzzard launched itself from the fence by the stream. Water voles are predated from the air by birds of prey, by herons and sometimes by corvids (which take baby voles). This is why w-vs usually swim keeping close to the banks, and if they do move out into open water they're always ready to dive down. The photos above are of two separate voles, but I saw two others who were too quick to photograph.
A check round the Staggs Brook by Black Park Road shows masses of feeding, much more than in previous years. I'd love to know how far up the brook the water voles extend. Do they go all the way to Blakemere, for instance?