They are, its all over the news down here... today they started around 8am, on the Venice side of the preserve. Like you mentioned above, I also wonder if he isn't there at all and the car being left there was a ruse and someone ferreted him out of there.
So, maybe he isn't there... or
He is there but, seeing as he was familiar with the place, had survival supplies already stashed... water purification tabs, mosquito spray, knife, rope, food, tarp, etc.
Haven't heard of vultures circling over any area in particular, they are all over the place here.