Desert Rosy Boa
Boidae, the boa family.
IUCN Least Concern.
Southern California into northern Baja California, southwestern Arizona and adjacent Mexico.
Desert and arid scrublands often near oases.
Their blunt tails led to the name “two-headed snake”, even though this name is most commonly used to describe the rubber boa which coils and hides its head, putting its tail out and shaking it to appear like its head.
They are slate gray in color with broad, longitudinal, irregular rosy-brown striping, smooth scales – almost metallic in appearance – heads only slightly broader than necks and blunt tails. Males have small “spurs” near their anal openings. Females can, but usually don’t. (Spurs are vestigial limbs, originating from the pelvic girdle, showing their primitive family’s relationship to the lizards from which snakes evolved.) They are mostly nocturnal and crepuscular, but are often found abroad during day, particularly when overcast and often after it rains
Their diet consists of small mammals, lizards and birds, which are killed by constriction. They are capable of constricting more than one prey at a time, which is useful when they come upon a litter of small mice, which they prefer.
They are preyed on by owls or red-tailed hawks and are said to coil into a ball sometimes when threatened, like their relative the rubber boa.
Mating occurs in spring, and after a gestation period of 130 days, females bear 6-10 live young (internally hatched eggs).