15 June 2016

Songbirds are well aware that birds of prey will eat them so they warn each other when they see one. Their warning calls can alert us, too, that a predator is circling overhead.

This American robin (Turdus migratorius) with one eye to the sky(*) is posed to search for hawks. When he finds one his warning call is a very thin, high-pitched sound at 7,000 to 9,000hz, similar to a cedar waxwing’s call.  Seeeet.  On the sonogram below it’s shaped like an eyebrow. If you have upper range hearing loss you won’t be able to hear it. Otherwise, here’s what it sounds like:

 

European starlings (Sturnus vulgaris) make a spitting sound that’s much easier to hear.

They sound off from a safe perch, or call “Danger!” as they take flight to avoid the predator.   In my experience, they only use this sound when they see danger in the sky.  Here’s what it sounds like:

 

When you hear these calls, look up to find the hawk.  Near the Cathedral of Learning it may be a peregrine falcon.

 

(*) American robins turn one eye to the sky because they don’t see straight ahead as well as they do side to side.  For more information see Anatomy: Field of View.