Reptiles

Rubber Boa

Charina bottae · also called northern rubber boa, two-headed snake

Least Concern → carnivore Temperate forest Mountains Temperate grassland

Pick up a rubber boa and the first surprise is how it feels — soft, loose-skinned, faintly cool, more like a length of moulded rubber than a snake. The second is that it will not bite. It just coils up, tucks its head away, and waves its blunt tail at you like a second head.

Overview

Charina bottae is a small true boa, a temperate member of the family that includes the boa constrictor and anaconda. It rarely exceeds 70 cm, with a stocky body, tiny smooth scales, a blunt head, and a short rounded tail nearly identical to the head. The colour is a plain tan to olive. It lives across western North America in forest, brush, and grassland, spending most of its life underground or under cover.

The decoy tail

The rubber boa’s best-known trick is tail mimicry. Threatened, it balls up with its head hidden in the middle and raises its tail to strike and wave like a head. This draws attacks away from the vulnerable head, and the cost shows: many wild adults have scarred or blunted tails from the bites of mother rodents defending their nests, because the boa’s main food is nestling mice, voles, and shrews raided from burrows.

Cold specialist

Few snakes handle cold as well. The rubber boa stays active at body temperatures in the low teens Celsius, prefers cool cloudy evenings to hot sun, and ranges far north into British Columbia and up to around 3,000 m in the mountains. It pays for the short active season with a very slow life — late maturity, breeding every few years, and lifespans past 30.

Status

The northern rubber boa is Least Concern, widespread and locally common. Its relative the southern rubber boa, confined to a few mountains in southern California, has a tiny fragmented range and is protected there as a threatened species.

Rubber Boa: common questions

Why is it called a rubber boa?

Because of how the snake looks and feels. It is small, rarely over 70 cm, with a stocky body, a blunt head, and a short rounded tail. The scales are small and smooth, the colour is a plain tan, brown, olive, or pinkish with a paler belly, and the skin sits loosely on the body in fine wrinkles. Handled gently, it feels soft and pliable and slightly cool, and the overall impression is of a toy snake moulded from rubber rather than a live reptile. It is a true boa, in the same family as the boa constrictor and the anaconda, just a tiny temperate member of that group.

Does the rubber boa really have two heads?

No, but it puts effort into looking as though it might. The tail is almost exactly the same size and shape as the head, with no obvious taper, and when a boa feels threatened it tucks its head into the centre of a coiled body and raises and waves the tail like a striking head. Predators and defensive prey animals then attack the tail rather than the vulnerable head. The tactic works well enough that a large fraction of adult rubber boas in the wild have scarred, scabbed, or blunted tails from the bites of mother rodents defending their nests.

Is the rubber boa dangerous or venomous?

Not at all. It has no venom, it is a constrictor that kills small prey by coiling, and it is one of the most placid snakes a person can encounter. A cornered rubber boa will coil up, hide its head, wave its tail, and if picked up may smear a musky-smelling fluid from glands near the vent, but biting a human is almost unheard of. This gentleness, combined with the snake's small size and slow movements, is why rubber boas are sometimes used by therapists and educators to help people work through ophidiophobia, the fear of snakes.

How does the rubber boa survive cold climates?

It is one of the most cold-adapted snakes in North America. It can stay active and digest food at body temperatures in the low teens Celsius, well below what most snakes tolerate, and it favours cool, cloudy, damp evenings rather than hot sun. This lets it live far north into British Columbia and high into mountain forests where the snake season is short. It compensates for the brief active period with a very slow pace of life, maturing late, reproducing only every second or third year, and living for decades.

Sources & further reading

Written by HideShark Editorial Team · reviewed by HideShark Science Desk. Published October 15, 2026. Last updated October 15, 2026.

Quick facts

Scientific name: Charina bottae
Diet: Mostly nestling mice, voles, and shrews taken from underground burrows, along with the occasional lizard, small snake, bird egg, or salamander; a hunting boa may eat an entire litter of young rodents in one raid
Skin like rubber: The small smooth scales, loose fit, and muted brown to olive colour give the body a soft, pliable, almost artificial look and feel, as though moulded from rubber, which is the source of the common name
A tail that mimics the head: The tail is short, blunt, and rounded, closely matching the shape of the head, and a threatened boa hides its real head in a coil and waves the tail as a decoy, so wild adults often carry tail scars from defensive rodents
Built for the cold: It is active at body temperatures that would leave most snakes sluggish, emerges on cool cloudy evenings, and ranges farther north and higher into the mountains than nearly any other North American snake, to around 3,000 m
Exceptionally docile: It almost never bites a person, instead releasing a musk or balling up, and its calm nature has led to its use in programmes helping people overcome a fear of snakes
Slow, long life: Rubber boas grow slowly, may not breed until nine or ten years old, breed only every few years, and can live past 30, giving birth to litters of a few large young rather than many small ones
A burrowing constrictor: It spends most of its time underground or under logs, rocks, and bark, is a capable burrower and climber, swims well, and kills prey by constriction like its larger tropical relatives
Range: Western North America, from southern British Columbia south through Washington, Oregon, Idaho, and Montana to northern and central California, and east into Wyoming, Utah, and Nevada, in wooded and brushy country.
Conservation status: Least Concern → ≈ Not quantified but widespread and locally common across western North America; the closely related southern rubber boa of southern California has a tiny fragmented range and is protected as a threatened species there in the wild