This was done on purpose for this study but, as you can see on the second and third link I am posting, they do it on their own in the wild - AND they also learn to recognize human alarm calls because mine all know what "BE CAREFUL - BE CAREFUL!!" meanshttp://www.sciencedaily.com/releases/20 … 124120.htmhttp://www.sciencedirect.com/science/ar … 7209005235http://rense.com/general50/warn.htm
When Sweetie’s first mate, Bubba, flew away she felt alone. A male Cardinal heard her calling and came to the window to console her. Except for eating and roosting he stayed right with her.She learned Cardinal and was making the same sounds back to him.