Wicken Fen - other samples of wildlife

Yesterday was a glorious morning and prompted an early walk.   Although it was sunny with virtually no wind, there were few birds to be seen.

However, there were masses of Swallows on telegraph wires at the Upware end, perhaps contemplating migration to southern Africa.   What I don't recall seeing before were Swallows sitting in trees.   As there was hardly a Swallow to be seen on the way back, it prompted the thought that perhaps they had been roosting on willow branches before spending the day catching insects.

The Buzzard made its presence known when it called out.

I expect the butterfly is a Common Blue and I have yet to identify the Fly, but I have seen images others have taken of the same fly.