More About Birds and Animals... Some Interesting News...
You might enjoy reading this AP story: Birds learn meaning of other species' call.
It seems that chickadees give specific information in their warning cries about the type of predator they have spotted, and nuthatches understand the specific information and respond appropriately.
For example, nuthatches understand chickadee warnings for small fast raptor predators and they respond by grouping up, ready to mob the threatening bird. The article describes how this was tested by playing chickadee calls on a loudspeaker.
The old expression that "Birds of a feather stick together" is still correct, but it's apparently not inclusive enough. These little birds operate more like the Arab proverb, "My brother and I against my cousin. My cousin and I against the enemy."
Nuthatches and chickadees are birds we often see around our feeders.
Public domain images from the U.S. Fish and Wildlife Service and the National Institutes of Health.