BBM The only thing that I could come up with is a loud parrot or another kind of bird. Or, the person who reported the "shrill" might have used the wrong term, maybe English is a secondary language to the person?
It's in the dictionary as a noun, just meaning a shrill sound, but isn't used much. It may be more common in some parts of the country. As a noun, it sounds (ironically) like a word you'd find in an Appalachian murder ballad, a usage that might trace back to old English.