Humans have tonal components to meaning, e.g. in English, "You are hungry." doesn't have the lift at the end as does "You are hungry?". I wonder if any birds do something similar to distinguish, e.g. "Predator!" vs "Predator?". Maybe someday an app on our phones will be able to translate as we walk through the woods, like "A female Carolina chickadee in the sycamore at 10 o'clock says there's a raven coming from the south".