Whilst checking nest boxes/utilising the energy provided by a piece of Bakewell tart/walking off the fat-store remnants of a triple-headed cone from Mr Whirl at Hartlepool headland, I approached Box 56 along the stream below Thrushgill clearfell
This seemed to be a clear cut case of empty box, flattened heavily soiled nest, no sign of any birds in the vicinity - typical of a Pied Flycatcher brood which would have left about 5 days ago. The nest was thrown out and the box cleaned. As soon as this was done, a/the male Pied Flycatcher suddenly appeared, making a racket and wing-flicking - the usual anxiety behaviour around an occupied nest
Furthermore it then followed me for a good 70m to Box 57 where an ex-Great Tit nest was similarly removed. During this process, the PF "defended" this box as though it was its own, calling,wing-flicking and approaching within about 2 metres
I moved on further up the river and it immediately lost interest. All previous alarm-calling had been limited to examination of/proximity to Box 56 with no prior example of being followed so far upstream to the vicinity of Box 57
Two pristine boxes if it wants to commandeer the/a female for a second brood!
Or is this just 'autopilot' behaviour?