Actually I went back and forth between the two.
The kingsnake simply rotated in the crack. It moved in a circular motion. Heating/drying?? one area, then another.
The blacktail, simply relaxed and stayed there. It saw me as it had its head out. Once they see you, all you can hope for is to be ignored.
When a kingsnake sees you, it will wait until you leave then quitely go down. Also to see you needs to be explained. I am sure if they see you at distance, it will not effect them at all. But the closer you get, the more it effects them and will cause different sets of reactions. Once you break their defenses, such as picking them up, that breaks down all nature behaviors but one, flight. From our studies, a certain percentage(30 someodd percent) will return to use the same area. The rest leave for greener pastures. Of course, this also varies from species to species. As do the distances.
Some common things of interest are, how they crawl. Different species do some amazing things. For instance, western hognose do a head snap. They crawl in a strait line and snap their heads strait foward. It looks like it would hurt. While willards do the kingsnake head wave. Waving their heads slightly back and forth, as they crawl forward. Cheers