brendank

Given that this bird has a rather dark bill and gray plumage (uppertail coverts aren't clearly visible), I suspect it would be almost impossible to separate from Red-throated without hearing calls had it not retained the nice red breast.  I have read that the timing and retention of red is different during post-breeding moult between Red-throated and Red-breasted. Are we simply overlooking many male Red-breasted Flycatchers that haven't retained red or would we expect most to retain those feathers?

brendank

My point was minus the extensive red throat and breast, I would say this bird would not really stand out as Red-breasted.  The bill does not really appear pale and the plumage overall doesn't appear to me to be particularly warm. There must be some adult birds that would be impossible to identify unless they were heard.