The mere sight of illness may kick-start a canary’s immune system
Simply seeing another bird get sick is enough to trigger an immune response in healthy birds
![yellow canary bird sitting on a branch](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2021/06/060821_jl_canary_feat.jpg?fit=1030%2C580&ssl=1)
Canaries (one pictured) can kick-start their immune systems to deal with potential pathogen threats before the birds actually become infected. In a laboratory experiment, being housed near sick birds prompted healthy canaries to mount an immune response.
Juniors Bildarchiv GmbH/Alamy Stock Photo