Theft at Diamond Head

So we are skinning up near diamond head at Blewett pass. While my pack was off, my helmet fell off and rolled down the hill to a cat track. We spotted it and figured - no worries, would grab it on our way back down. A few minutes later, I hear (but can't see) two snowmobiles come up the track, stop, and take off again. While they stopped, I yelled down do leave the helmet, that I was coming back for it. When we got down, the helmet was gone.

Is this typical behavior of snowmobilers?

Yes, but we usually steal your beer and women...
All joking aside, by chance did said snowmobilers have there helmets on? It can be hard to hear with a helmet. You may want to check snowest.com to see if maybe they posted a found post.

I'm having a hard time visualizing where the cat track is near Diamond Head.

Near diamond head, not directly at it. NF 9712. We were climbing up an adjacent hill right across from diamond head.