[rthomas6]

There really are birds that have predator warning calls. Other animals even listen for them and hide when they hear them.

[trgn]

We can always tell when our neighbor's cat is outside when the birds in our yards start to get agitated.

[dontcarethrow2]

I've noticed the warning call differs at times, I hear two chirps for land based predator and three for air. Small sample size, city finches.