Mystery

Anyone have any idea what these bird cage like things are? We would love to know - it's been bugging both of us for a week, and we haven't gotten any answers yet. Here's what we do know:

1. There are 5-10 of them in this fenced in area spread out but not in any apparent pattern.
2. It looks like there may have once been a paved parking lot at the site. (It's hard to tell when you're talking Arizona desert - it could be concrete or just packed dirt.)
3. They are located just north of Picacho Peak right along the side of I-10.
4. They look like they may have a door in the side of the basket thing on the top, but there are no steps attached to the pole.

The game is afoot! :)

God bless!