Hi discretion. How exciting. You picked out a sign from this jumble of rocks that is a sign. Now the t-bird itself may or may not be Spanish..I do not know. But I get a thrill when I find signs like that..start thinking who might have made it, what its purpose was, the history..look around and imagine the people traveling, and so on and so forth. Civilizations rising and falling.. well it just goes on and on. Kind of makes you feel part of the land and the history of a place. In my area there was a concerted effort to wipe out
"pagan" signs by the Spanish so it is a really special treasure to me to find one or more.
Spanish sometimes reused monuments..it is not clear at all to me if that sign came before or after the Spanish. For there truly are Spanish signs there. If it is a thunderbird, I am surprised to find one in California..thought it was a southwest thing but have not researched it.
The thunderbird then may have been put by different people...though it is pointing to the right like some of the other signs. If it was put by other people..well follow it and see what happens
You might find a spring, a lovely cove, pretroglyphs..who knows. Heh.. check out whats over the next hill, around that next curve. What could be a better endeavor on a lovely fall day. smiles.
Though I am still learning my self I am 100% with minetrees on this. You have stumbled onto what is also a Spanish end point. If you have been studying the other threads and pictures, you will have found mention of turtles, owls, lambs, even bells. Looks to me like you have all of those on this monument.
To me that means something is close. To me it also has a lot of things saying right..go right. Now as to final measurements..if you decide to pursue it a bit of studying and experimentation will be in order. Kenworthy's books are a great place to start. Gleaning hints such as what minetrees so graciously gave you and as others have posted in this forum is a good way to go too. I would mark some cept I am not sure of how they work etc. but it seems to me there are numerous carvings on and near the monument that
might be near to final directions.
Even if you do not pursue it to that level you've found an excellent example of at the very least, a Spanish monument. Perhaps your eyes will be opened to other things and you will be amazed like I was..at how much is out there when you go traipsing about.
In the back right there you have an owl looking at you face on. If you care to post a bigger picture I would be interested in seeing what is on that hill or mountain behind it. Nothing to do with this site..but big geo signs are an interest. I think a variety of groups made them and I find them fascinating. Migration or religious perhaps.
Owls generally a favorable sign though they may not always be Spanish. Given its closeness to the turtle..I would think it is Spanish.
For me..an owl facing you can mean 1 of 3 things. 1. Look where owl is looking. 2. Look under the owl (I do not mean dig.) 3. Look in general area around owl.
There seems to be a bell on the left circled there...can you see its clapper? On the right a lambs head with one ear up and pointing right. Um..you probably can not see that..but over time the curves of a lambs head and ears..become familiar.
Well.. a different time of day may make the thunderbird come out clearer..or dumping some distilled water on it. Hope you enjoy your historic find and continue to find time to follow ancient trails with perhaps new eyes.
Maybe it's that guy in Texas. 
