I presume it got into conflict with the Great Tit, and lost (and in such a case my money would generally be on the tit). This is the second year I have had such an event. Last year I was clearing out a Great Tit’s nest after the young had fledged in another wood, and felt a hard lump under the nest material. This turned out to be a dead 5 (Juvenile) male Pied Flycatcher, ring number T600535, which I had ringed as a nestling in that wood in 2008.
Posted on behalf of David Coker. Photo from Dick Jeeves.