They know best

The garden Blackbirds were waiting for their daily supply of apple to be served this morning so I duly obliged, and took up a perch myself to watch them for a while.
One of the birds stopped feeding and kept quite still with its head over to one side.
Remembering an old tip that the bird is probably watching something above, I followed its gaze and sure enough, quite high up, a soaring Sparrowhawk, which continued on its way.