Central and west Texas through most of New Mexico and north into western Oklahoma and southeastern Colorado. Also extends south into central Mexico.
Can be found in a wide range of habitats, but generally prefers rocky soil and semi-arid surroundings. Most abundant in desert scrub and grassland areas in elevations from 3000-8500 feet. As its name suggests, it is a nocturnal snake.
This snake averages 10-16 inches in length and has a light tan background with dark tan patterning. The top of its head is solid dark tan, with a light tan jawline. It has more prevalent dark tan on its neck, which can be a solid collar, or irregular thick patterning. The pattern down its body consists of large blotches down the center, sometimes in 2 alternating rows, with smaller irregular spots on the sides of its body. Ventrum is unmarked and pale. Has vertically elliptical pupils.
Learn more with Schechter Natural History's Guide to Reptiles and Amphibians