azblackbird and azdave35,
Thanks for the replies. I should have a little better handle.
The point for me is that there
should be a paper trail if it was a guano mine.
I did look around a bit on the Maricopa Recorder's site and with nothing to search on, the task of locating any paper work would be daunting.
The very least would require a narrowing of the timeframe.
Right now there is a reference on DesertUSA that was credited

to Joe Ribaudo that he thought it was from a quano mining project in the 1930's. I have also seen the 1940's or 1950's referenced. There is another reference that someone felt the ladder (by appearance) was only 10 or 15 years old. Tom Kollenborn and Jim Hatt visited the site in about 1994 or 1995 and Tom had no recollection of the ladder being there but he later said it must have been.
I HOPE I GOT ALL OF THE ABOVE RIGHT!
I'm still lost on what type of equipment would have been used to collect the guano. Large suction hose, shovel and bucket, etc. I'm also still wondering how they got it down. In buckets? Seems pretty slow and tedious for guano. I would have thought it would require a pretty high volume process.
Right now I wouldn't bet a dime, one way or the other, that there was ever a guano mining operation there.
Another thing I may not be understanding but are there signs of a hard rock mine in the cave? Could that have been the reason for the ladder? Is there also a prospect hole down below the cave. Regarding their visit, Tom talked about Jim Hatt exploring some mine below the bat cave?
Did the Forest Service build it to monitor the bats and with the passage of time it's history was lost to the Forest Service?
There well
could be paper trails for these other scenarios also.
Where is Somehiker!!!!
Garry