The first time I heard this sound in the dark, I had no idea what it was.
For those of you who don’t live where there are raccoons, I can tell you they are much more dog-like than you’d expect from animal that isn’t actually canid species. When you look into the eyes of a raccoon, it’s like looking into the eyes of a dog. This is a creature with a mind.
Probably the best way I can describe them to those who have never seen one in the flesh is they are kind of like a dog mixed with a primate and a bit of bear thrown in for good measure.
And when they are scared, they make lots of strange noises, including this alarm bark that sounds a bit extraterrestrial.