This rather stunning wagtail was found on the Narrows this morning. It was initially thought that it may be a dombrowskii Wagtail, a hybrid between the nominate flava and Black-headed Wagtail feldegg. It is very striking, no matter what it is. There is also Eastern Yellow Wagtail M.f.tschutschensis to consider that appears indistinguishable from dombrowskii.
Unfortunately the call of this bird to my ears sounded fairly like a normal flava wagtail, and not very buzzy.