Bird-brained chaffinch keeps banging its head against our window

For several weeks a pair of chaffinches have been repeatedly flying into our sitting room window.


We think they do this to be aggressive towards perceived competition, i.e. their reflection. It's usually the male who perches in the fig tree, then flies up at the window, bashes its beak once on the glass, and returns to its perch.


This happens every two or three seconds until, I suppose, it gets fed up. Or until I get the camera out to try to get a better photo.


The stupid chaffinches have done this to the kitchen window as well. Every day we'd hear a regular tapping - it has died down a bit now.