Ancient ritual sees birds battered to death with a hammer then thrown out of the home; in offshoot custom, boiled egg yolk can determine luck.
Ben Rogers, co-founder of Hong Kong Watch, told Premier Christian News the law was part of a wider effort to increase state control.
Experts say the new provision would be a setback for the identity of ethnic minorities because it would mandate using Mandarin Chinese in compulsory education, among other things.