YAQUI BLACK-HEADED SNAKE
A small (up to 325 mm or 13" in total length), gray or tan snake with a dark gray head cap.
The posterior edge of the head cap is bordered by a thin white or cream collar. The head cap extends well back (usually 2 to 4 small scales) behind the parietal furrow (central seam between rear-most large head scales). The dark head coloration wraps down the sides of the neck behind and below the corner of the mouth. A white patch marks each cheek behind the eye. The belly is cream anteriorly grading to light pink or orange posteriorly. The scales are smooth and the small head is barely distinct from the neck. There are enlarged, grooved teeth in the rear upper jaw.
This snake is known from the Canelo Hills and the Pajarito, Atascosa, Santa Rita, Mule, Chiricahua, Swisshelm, Pedregosa, and Peloncillo mountains of southeastern Arizona. In Arizona it is found at elevations ranging from 3,300' to about 6,000'.
It is found in Madrean Evergreen Woodland and Semidesert Grassland communities. It is usually found in rocky, wooded canyons and on neighboring slopes.
This secretive, nocturnal ground-dweller spends most of its time burrowed under rocks, logs, and leaf litter. It is occasionally encountered on the surface on moist nights. Most near-surface activity seems to occur under cover on moist spring days. It hibernates during the cold months of late fall and winter.
Venom is delivered to prey via enlarged, grooved teeth in the rear upper jaw (not considered to be dangerous to humans). It forages under rocks and leaf litter for a variety of invertebrates.
Reproductive behavior is poorly known. It probably lays a small clutch (<4) of eggs in summer.