After growing more worried for him, I decided to google what to do. I learned that he was most likely tweeting to his mom, who could hear him from two blocks away, but was most likely too scared to come get him because he was near us. We then decided to move him away from us.
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but this one was obviously in a later stage. mother would therefore have more invested in it, and a reason to come looking for it. still, it would depend on the species. (a wren?)