If you saw your good friend catch a bird and put it in a cage, what would you say and do?

That depends on how it comes from: if it is caught in the wild, let your friend set it free. Wild birds belong to the sky. If you buy it in the bird market or other places, you will keep it. After all, artificially bred birds can't live if they are released. Please respect life, don't be mean and selfish, hope to adopt it.