Bizarre Vacuumous Sound

[Hunter of the Dead, Corrupter of the Tomb, the Deadthings]

A little over a year ago, I recorded this really bizarre sound coming from outside my house! It starts out with a high pitch whine and morphs into what sounds like a vacuum. I have a Youtube video of the recording:



I have looked all over the net to see if anyone has heard this sound and I've found nothing. If anyone has any idea of what it is or if you've heard this sound, let me know.