GeoGraph - photograph every grid square

Fledgling on a hot slate roof

This very young Grey Wagtail was out on the roof all afternoon, initially cheeping a lot while standing up but later quieter and in this kind of squat. By evening it was gone. Had it taken the plunge, so to speak, and used its wings to fly or had it met some other fate? The roof is inaccessible to cats.

Thanks to Hugh Venables for the identification. He suggests that it looks like it might have been out of the nest too early. So only a semi-fledgling?