Why are chickens elsewhere in S’pore not culled too?

I refer to the letter “Free-roaming chickens culled for public health reasons, not noise” (Feb 14). So, the Agri-Food and Veterinary Authority is anticipating bird flu and has culled the chickens as a preventive measure.

The letter mentioned the joint statement the World Organisation for Animal Health and the Food and Agriculture Organization made 13 years ago about “battling bird flu ... at source”. This is a surprise.

There are more such fowls in the Botanic Gardens and Pulau Ubin, just to name two places. If the risk of free-roaming chickens being exposed to bird flu is “real and significant”, why are these birds not culled too?

What about other birds across the island that are susceptible to the disease? Are they not in danger of being infected by migratory birds? My perception is that the AVA is unable to admit its wrong decision about the cull.