Why didn't the birds who came back from other places receive the message to do nucleic acid?

It may be the national accounting census.

At present, during the epidemic, when the epidemic is very severe, some places sometimes do regular national accounting and conduct epidemic investigation and screening to ensure the safety of the region.

Big data can sometimes make mistakes, and it can be based on my own area. If there is no epidemic, I can ignore it. Because there is no epidemic in some places, I don't need to do nucleic acid testing. If it is available locally, it should be strictly checked at the local nucleic acid detection point according to the data requirements.