Which whistle-like instrument is used in Caravan Palace's “Cotton Heads”?

Question

I've been trying to transcribe Caravan Palace's "Cotton Heads", and have been failing to find an instrument that has the almost human whistle-like quality in the song.

The instrument appears in the video at around 0:46 but reappears rather consistently throughout the song.

Answer 1

This is very likely a synthesized sound. It also could be based on one or more samples of a person whistling (or some other foley sample with similar characteristics), pitch shifted and then heavily manipulated with layers of effects to achieve the desired timbre.