The thunderbird is a bit odd to talk about. The wingspan I would estimate at 120-130 yards/meters. It is horribly eroded, and in one spot has been damaged slightly by a landslide or rockfall.
Indeed, I would describe it as the remains of something, because you cannot always see it.
In the Autumn of the year, the sun hits at just the right angle for about an hour each afternoon, and it is right there, plain as day, plain as the nose on your face. Everyone we've ever taken to out there to see it, (roughly a dozen people including family members), has seen it. Nobody has ever said, "No, there's nothing there but your imagination".
Now, I have hiked all over that hillside, which is not an easy task. It's steep as hell, and covered in broken rock, loose sand, prickly pear, barrel cactus, spiny yucca and several dozen other varieties of thoroughly inhospitable cacti. But I've hiked it all over, and there's nothing to be seen close-up.
Yet in the Autumn, in that one hour or so of late afternoon sunlight, it's there. It could be natural. I've gone back and forth and back and forth in my opinion.
But there have been important archaeological finds made because low-angle light picked out the remains of foundations that were invisible to the naked eye from close-up. Usually this has involved aerial photography, but the principle remains the same.
So, justification for Von Danikenites, or over-active cannabis-fueled Southern California imaginations...you decide
