heres a pic of the area I put him in

I live in SoCal so it's still relatively sunny and warm.I had them out there for 40 minutes, checking up on then every 15-20 minutes. When the 40 minute mark hit I went to get the turtles to take them back inside. I quickly spotted the first, but the other one was MIA. I went and put the first turtle back in his enclosure, and went back outside and meticulously searched every nook and cranny of the area. The walls are about 5 inches tall, so theres no way he could have climbed over them, next I looked around the permimeter to see if there were any holes that the turtle might have dug out of, none that I could see. I looked did a quick skim around the surrounding area and found nothing. I'm seriously at a loss right now, we do have hawks in the area but the crate is covered so I doubt they would have seen him... How do u think he could have escaped in such a short amount of time. I'm scared I'll never be able to find him again, he's so tiny.

