My understanding is that squab is young pigeon, probably fledged but not out of the nest. (Hence the nest box idea ... "1, 2, 3 ... hey, where's little Charlie?" ;-)

Adult birds are said to be a lot tougher. The ones I've had were done in a slow cooker, in sauce.

I don't think I'd fuss with plucking a bird that small. Just take the breast and drumsticks. The ravens will clean up the rest.