Have you been lucky enough to see Idaho’s only boa constrictor? The rubber boa is smaller than the giant boa constrictor of South America and its secretive nature makes finding one noteworthy.
I saw my first rubber boa basking on the Long Canyon trail. Stretched across the trail in a sunny spot, the rubber boa was smaller than I anticipated since I had pictures of the giant boa constrictor in my mind. Rubber boas usually range from 14 to 28 inches long and this one was on the low end at about 14 to 16 inches.
The rubbery appearance of the boa distinguishes it from the other two snakes that reside in North Idaho, the common garter snake and the western terrestrial garter snake, which have stripes running along their length. The rubber boa is uniformly colored on its backside with colors ranging from tan to brown to olive green. The boa’s underside is yellow to cream and may have black or brown mottling.
Loose skin and small, smooth scales lend to the boa’s rubbery appearance and help it resemble a giant brown worm.
Like a worm, distinguishing the head from the tail can be tricky (unless they are slithering away). The nickname “two headed snake” comes from the rubber boa’s uniformly thick body which tapers to two blunt ends. Their small eyes help keep the mystery of which end is which from a distance–especially for predators.
To protect its head from predators, a rubber boa coils into a ball with its head tucked underneath and its “second head” sticking out. The boa evens jabs its tail about as if striking to deter predators (such as hawks, coyotes, raccoons and skunks) and if that doesn’t work, the boa can release a smelly musk from its vent.
Often a rubber boa bears scars on its tail from predators and defensive rodents. When the rubber boa is raiding a nest of baby rodents, it uses its tail as a club to keep the mother rodent out of the nest as it swallows the nestlings whole.
Rubber boas also eat adult rodents but will kill them by constriction. As the rubber boa wraps its body around the prey, it squeezes until the prey stops breathing and the heart stops. In addition to rodents, the rubber boa consumes bird eggs, nestling birds, nestling bunnies, small lizards, other snakes, salamanders, small chipmunks and even bats.
The nocturnal nature of the rubber boa keeps its life secretive though females will bask in the sun in temperatures between 65 to 75 degrees. Pregnant females need the sunshine and warmth for the healthy development of the young born in August.
Otherwise, rubber boas spend most of their time under logs, rocks, and forest litter or in rodent burrows. Researchers have even determined that rubber boas will rest beneath rocks of a certain thickness in order to thermoregulate more efficiently.
The secretive nature of rubber boas and their nocturnal nature make seeing a rubber boa a real treat, so count yourself lucky if you see Idaho’s only boa constrictor.
Originally posted May 2014. Updated April 2024.
Thank you for this information, I think it has helped me I.D. a couple of rubber boas I have seen over the past couple of years.
One was brown like putty, and more recently a grey one with a green tinge and light green under the chin.
I live in Shoshone County near Cataldo.
Cataldo Kelly
Just because boa constrictors are in the same family as rubber boas, that doesn’t mean it’s a boa constrictor.
Besides it’s not the ‘only’ one either. There’s also the rosy boa that roams around Idaho too!
Hi Lucy,
Thanks for the information. According to Idaho Fish and Game, the Northern Rubber Boa is the only boa in Idaho– that is where I found my information. If you have seen a rosy boa in Idaho, you could report a sighting to Idaho Fish and Game.
Laura
i was lucky enough to spot a rubber boa on the tubbs hill trail in coeur d’alene. very distinctive looking appearance. you described it well!
Thanks for sharing!
Laura
Found a Rubber Boa down here at the palisades by the Wyoming border just yesterday day, in fact it was an adult and a baby.
Wow, finding an adult and a baby is awesome!
Thanks for sharing.
Laura
I’ve had a pretty good sized (about 28″) rubber boa living in my raptor breeding chamber for the last three years or so. The chamber’s been out of service for a couple of years and the snake has been living in an old rodent hole in one corner along the foundation. Unfortunately, it didn’t realize the chamber is now back in use with a couple of feisty adult redtailed hawks. I just found the birds dining on the dead boa. It must have poked its head out at the wrong time. An understandable reaction by the birds, but I’ll miss the boa; he was pretty cool. I’m in southwestern Idaho, so the rubber boas must be well distributed throughout the state.