This lady in 雀仔街 （雀鳥花園）clips the wings of small birds so that they cannot fly away. Take a close look at the wings of the love bird on the stick. The largest feathers have been trimmed by about a inch. It is just enough to still enable the bird to flutter for a short distance, but no more than that. It must be very frustrating for the bird.
She then ties them to a stick through a string, and trains them to sit still. Then to climb over her. Finally, to hide inside her clothes. She claims that they do not suffocate, and actually likes to hide inside her clothes.
The birds seem to be mostly love birds and cockatiels. I counted at least 3 birds inside the sleeves of her jacket while we were watching.
I imagine some people may object to such treatment.