Re Fairchild Swamp bird nesting islands:
http://www.pitriveralliance.net/ijourney/warmsprg/fairchcb.html

Re Boles Meadow bird nesting islands:
http://wwwnotes.fs.fed.us:81/r4/payments...3e?OpenDocument

As for other circular features in this set of placemarks, they are entirely consistent with mima mounds, a common natural feature of prairies in the western US.

Methinks the original poster is too credulous by half...