I received these photos from a friend today - a slightly larger than average size bird tapping on the window glass; maybe a brownish body with a white throat and white beak and black head.
The tail is spread in a fairly wide fan, maybe to scare "the other bird" reflected in the window?
There's a front view and one with its head turned, but it's a little tricky to be sure of the colors since the sun is (roughly) behind the bird. I suppose it's possible that the beak may not be white, but just smooth and shiny and reflecting the sunshine.
Taken on a sunny, hot July afternoon in July in Taipei. Coat hangars for scale suggest it's a bit larger than the typical bird.
It reminds us somewhat of a Chinese Bulbul, but those distinct vertical stripes between its throat and breast are very distinctive.
It looks scary/predatory, could it be a juvenile hawk?
Chinese Bulbul photos (mostly from Hong Kong):
Light-Vented Bulbul (also Hong Kong)