Silly situation we've created in Hong Kong.
We put glass up in the form of windows and particularly barriers of various forms everywhere, unfortunate migrant birds crash into them, then we (or rather our collectively ridiculous 'authorities') get all worked up thinking the birds have died of some killer disease, when in fact man has probably created any such disease himself through his own animal management practices, and which he himself imports into Hong Kong.
But maybe it's easier to just demonise wild birds.