I was living in Chengdu for a year and I remember that I was surprised by the almost total lack of birds. In Hong Kong, where I am at the moment, there are more birds, but seems less than what we have back home in Northern Europe.
"birds are public animals of capitalism"
Hongkong has the advantage that it is actually very small and dense with nature (in hills and parks) never far away, which I'm guessing helps a lot in sustaining a more abundant and diverse bird population.