Mountain Kings can be found in most of the wooded canyons of the mountains in central and southeastern AZ. You just need to get out in the morning and hike around looking for them. They are After rain is good, but they come out when it hasn't rained as well.
They aren't rare, but you just have to put in the legwork. They are generally found out crawling around around big rockpiles, streambeds, even climbing up the trunks of trees.
Get out there, look, and you should eventually find them. Canyons that have water flowing are probably better than dry canyons, but they aren't down in the canyon bottoms.
If you really want to know, get Brian Hubb's book "Mountain Kings". It is the best reference for where and how to find pyros and zonata. It is available at herp expos or online at mountainkingsnake dot com.
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Chris Harrison
San Antonio, Texas