How weird. I have seen false nesting in which a Mt.Tortoise started to build a nest (they build above ground)then would just abandon it. Box turtles will do that but as a decoy, but dig and lay near by. My gut reaction if they were mine would be to give them some oxytocin next time. I had asked on this forum last year if anyone new if oxytocin kicked in "nest construction" or just the "egg laying" I got a mixed responce but most said just the egg laying. You could get them X rayed and get your answer quickly. VM