Far from the Madding Crows

I was originally going to name this piece either Pigeon Post, after the Arthur Ransome story, or Like a Bird on the Wire, after the Leonard Cohen song, but then I accidentally came up with the typo above which seemed to fit a bird-related post.

The pictures come from the point where Johnston Road turns off from Hennessy Road in Wanchai by the Chinese Methodist Church.  For some reason, large flocks of pigeons regularly gather on the tram lines at this point.  What puzzles me is why they choose this particular perch - some nearby food source perhaps?  Or are they devout Methodist pigeons waiting for the next service to start?  Perhaps any ornithologist reading this could suggest a reason.