Scientific name: Charina bottae PDF version of this page
Rarely does a name suit so well! Between 35 and 80 cm long and fairly thick-bodied, the Rubber Boa resembles a rubbery tube with a slight taper at each end – similar in shape to what you’d roll out of a ball of clay. Its loose skin and many small, smooth scutes (scales) combine to give the snake its rubbery appearance. Adult Rubber Boas are dark olive green to brown in colour, and their bellies are pale yellow to orangish yellow. As juveniles however, their small size and pinkish colour are strikingly similar to that of an earthworm! However, the Rubber Boa is much more fascinating than its simple exterior suggests.
Also known as the “Two Headed Snake”, it can be difficult to tell a boa’s head from its tail. Rubber Boas have little to no neck and their eyes are tiny. When being attacked, the Rubber Boa contributes to the confusion by curling in a ball and hiding its head beneath its body. The tail, equipped with a small hard cap, is then presented as a decoy, and the snake often will jab its tail about as if striking. This way, the snake avoids any harm to its vital head region. If the predator remains undeterred, Rubber Boas can release a smelly musk from their vent. However, that’s as much as this sluggish, secretive snake can muster – Rubber Boas never bite, and are happier hiding beneath a damp log than waging battle.
A true boa constrictor, the Rubber Boa belongs to a famous family of snakes. This family includes, among others, Reticulated Pythons and Anacondas! As evidence of this relationship, the Rubber Boa has tiny vestigial (remnant) limbs on either side of its vent. These tiny ‘spurs’ are more obvious on males than females. These vestigial limbs are found on boa constrictors all over the world.
Click here to visit the Rubber Boa Photo Gallery.
Like all of B.C.’s snakes, Rubber Boas spend the winter hibernating in underground dens (hibernacula). While boas will hibernate communally with other boas, unlike many other snakes, Rubber Boas do not appear to share their dens with snakes of other species.
Mating occurs in spring after emergence from the hibernacula. Young develop within their mother’s body. When completely developed, the young are born live. While Rubber Boas can be active at relatively low temperatures, pregnant females need more sunshine and warmth than usual to ensure the healthy development of their young. Pregnant females carry their young until mid-August when 1 to 8 earthworm-like neonates (newborns) are born.
Rubber Boas usually are crepuscular (active at dawn and dusk) and nocturnal, and they function well at these cooler temperatures. Perhaps due to their slow, sluggish life-style, female Rubber Boas may reproduce only every 4 years. On the plus side, however, they are a long-lived snake, living up to 30 years.
Rubber Boas eat fairly infrequently, even compared to other snakes. When they do eat, however, Rubber Boas use two main tactics to gather their usual meal of mice or shrews. When preying on adult rodents, boas constrict their prey, wrapping their body around the prey until its heart stops and it can’t breathe. When preying on baby rodents, boas use their tail as a club to keep the mother rodent out of the nest while they swallow the nestlings. In fact, many Rubber Boas are heavily scarred on their tails from the bites of mother mice.
Rubber Boas are not limited to hunting at ground level. These snakes are able swimmers, climbers and burrowers, enabling them to diversify their diet. Other items that boas eat include bird eggs, nestling birds, nestling rabbits, small lizards, other snakes, salamanders, small chipmunks, and bats.
Rubber Boas are found from southern B.C. to as far north as Williams Lake. Within this region, boas can be found in woodlands, grasslands, coniferous forests, dry pine forests, Juniper woods, and riparian areas. Within these regions, however, Rubber Boas tend to avoid dry, hot areas enjoyed by many other snake species, preferring instead humid mountainous areas. In fact, all three known boa hibernacula were found in wooded areas.
Rubber Boas use a variety of features within the landscape for protection and for hunting. These items include abandoned rodent burrows, rock crevices, rotting stumps, logs, bark, litter around development, and decomposing sawdust piles. Because they like to burrow, they appear to prefer sandy or loamy soils.
Rubber Boas are able to use their environment very effectively to maintain a comfortable body temperature. Scientists found that boas can select rocks of a certain thickness to rest beneath in order to thermoregulate more efficiently.
Click here to see the Rubber Boa Range Map.
Rubber Boas are vulnerable to many of the same threats faced by other snake species. While basking along roads in the evening, boas are killed by cars. Habitat continually is lost to urbanization and agriculture. And because of their mild nature, individuals are illegally collected from the wild. Snakes removed from the wild often die because of the highly specialized care they require. If you see a snake, look at it, admire it, but leave it alone!
Their low reproductive rate and the patchy distribution of habitat could reduce Rubber Boa populations to disconnected pockets of individuals. This in turn could make the species vulnerable to a loss of genetic diversity, and eventually to the loss of entire populations. For these reasons, the Rubber Boa is listed as a species of special concern federally. If you see a Rubber Boa, contact your local branch of the Ministry of the Environment.