Talk to any longtime bird-keeper in Ho Chi Minh City and they'll describe the hobby's history the way a sommelier describes vintages — in distinct "waves" (luồng), each with its own dominant species, its own migration story, and its own economics.
Bird-keepers in Saigon mostly favored two species: chào mào (red-whiskered bulbul) and chích chòe than (oriental magpie-robin) — hardy, widely available birds that remain popular to this day.
A new wave rises around họa mi (Chinese hwamei), carried south by migrants from Lạng Sơn and other northern provinces who brought their birds — and their bird-keeping culture — with them when they resettled in the city.
A striking Southern bird called thanh tước — blue-bodied, with a yellow tuft on its head and a purple-black ring around its neck — becomes fashionable. It's so admired that the trend reverses and flows north, with Hanoi keepers seeking out Southern-caught birds; today it's rare and expensive even in its home region.
Khướu (laughingthrush) from Quảng Trị province begins arriving in large numbers, sparking a new wave of khướu-keeping across the city.
Successive avian influenza outbreaks devastate the hobby community. At the worst moments, keepers release their birds outright, or hide and quietly relocate them to keep the flock alive through inspections. Large birds like khướu and chích chòe lửa — which need big, conspicuous cages that are awkward to transport on a motorbike — fall out of favor as a result.
In the wake of the crisis, chim sâu (small insectivorous birds, in green and red varieties) become the practical choice: cheap, small enough to hide in a modest cage, easy to trade, and good singers besides. The chim sâu market booms, peaking around 2008.