Snakes in the genus Pituophis are medium sized members of that very speciose family of snakes, Colubridae. The genus is restricted to North America and northern Central America and their closest relatives are the new world "rat snakes" (don't use Elaphe... jump on the Pantherophis bandwagon!), plus other Lampropeltinines like the kingsnakes and milksnakes. Pituophis are primarily rodent specialists (many species are commonly known as "gopher snakes") and perhaps not surprisingly they can often be found in or around rodent burrows within their natural ranges.
One rather key bit of natural history of Northern Mexican Pinesnakes is that they come from the dry, open mountains of eastern Mexico. Living at these higher elevations, they have adapted to thrive at cooler temperatures than other Pituophis, have a slower metabolism, and can take 3-4 years to reach sexual maturity instead of the usual 1-2. There are two recognized subspecies P. deppei, the other being the nominate race, which occurs further south west than P.d. jani.
modified by me from Rodriguez-Robles & De Jesus-Escobar 2000.
Orange curve roughly contains native range of P. d. jani... maybe.
As for the youngster in the picture above, it's only 7 months old, currently weighs in around 40 grams and is a little over 18 inches long. Tiny considering that an adult can push 6-7 feet in length...
The first individual above was hatched by friend of mine this past fall - that's one of her adults at an educational event in the picture above. You can see even better photos of this big fella over at Biological Ramblings.