If you find a dead bird with no sign of trauma; it's not a bad idea to call the authorities. Picking up and moving a dead bird is insane and should never be recommended when avian flu abounds.

The local authorities can test for West Nile as well as bird flu (quite a few other diseases as well). Which leads to heightened awareness and increased containment measures in the community.

Tldr: What I don't get is how do the cats know they are infected... Never see them touch a sick bird.

Edit: Nvm on the cat bit, https://www.livescience.com/57583-bird-flu-h7n2-strain-strikes-cats.html...