Any other thoughts on this particular snake? My book says that they have a preference for smaller prey in general. Have you found this to be the case?
I find they are hardy snakes that fare well in captivity.
I keep mine the same way I keep all my snakes, but I find they don't generally spend much time in the hidebox that has the heat tape, except right after eating. My room is kept at 70-75°F most of the time and the heat tape is around 85°.
In their natural range, it gets cool at night (mid to low 60s) most of the summer but they tend to be active during the earlier, warmer times of night.
They generally eat smaller prey, but adults readily take large mice or even small rats. They won't eat the huge meals that obsoleta will choke down, but they will eat most things that a snake of similar girth will eat. They are actually docile, shy snakes, so I only feed them pre-killed prey.
They don't like to be wet (if you spray them with water, the go crazy trying to get away). Some people say you shouldn't leave water in the cage, but I haven't had any problem as long as the cage remains dry and well ventilated.
VPI has a decent care sheet about them - http://www.vpi.com/8VPICareSheets/Colubrids/TransPecosRatsnake/TransPecosRatDesc.htm
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Chris Harrison