Cats do chirp, don't they! One of mine follows me around "mrrrp-ing" all the time.
When they're especially interested or captivated.Even the big cats chirp at least as babies, I've heard them..adorable…on ZooBorns.Cats say all sorts of stuff…Tizzy is a real talker…Fred squeals as I put his breakfast kibble down in the morning. Both are real characters…as I'm sure yours are as well. :~)