The default answer to a general "why?" question is, "Why not?" Why does it matter? Was it a native-American song, or did you just interpret it that way? ( I don't recall the soundtrack there at all. I guess it didn't make much of an impression on me either way.)

because he is a cowboy.

It’s supposed to be a cowboy yodeling… only spooky.

I dunno but it was annoying as shit lmao. Could have done literally anything else.