Rubber boas are nonvenomous snakes native to North America. They are one of the smaller boa species. The common name is derived from their skin which is often loose and wrinkled and consists of small scales that are smooth and shiny; these characteristics give the snakes a rubber-like look and texture. Colors are typically tan to dark brown with a lighter ventral surface but sometimes olive-green, yellow, or orange. Newborns often appear pink and slightly transparent but darken with age. Rubber boas have small eyes with vertically elliptical pupils and short blunt heads that are no wider than the body. One of the most identifiable characteristics of these snakes is their short blunt tails that closely resemble the shape of their head. Rubber boas appear quite different visually than any other species that share the same range (except maybe for the Southern rubber boa) and thus are usually easy to identify.
The distribution of Rubber boas covers a large portion of the western United States, stretching from the Pacific Coast east to western Utah and Montana, as far south as the San Bernardino and San Jacinto Mountains east of Los Angeles in California, and as far north as southern British Columbia. There have also been rare sightings in Colorado and Alberta in addition to the states/provinces that they are known to thrive in California, Washington, Nevada, Utah, Wyoming, Montana, Idaho, and extending to its northernmost range in British Columbia. Rubber boas inhabit a wide variety of habitat types from grassland, meadows, and chaparral to deciduous and conifer forests, to high alpine settings. They are not as tolerant of higher temperatures as other snake species and cannot inhabit areas that are too hot and dry, but can live in areas that are surprisingly cold, especially for a snake.
Rubber boas are primarily nocturnal and likely crepuscular (active during dawn and dusk) creatures. Because of the temperate regions, they inhabit these snakes hibernate during the winter months in underground dens, usually communally. Rubber boas are extremely adaptable snakes. They are good climbers, burrowers, and even swimmers. They spend a large amount of time under shelter (rocks, logs, leaf litter, burrows, etc.). It is also thought that Rubber boas maintain a relatively small home range as many individuals are often captured in the same vicinity year after year, although individuals may occasionally migrate due to competition, lack of prey, or other pressures. These snakes are considered one of the most docile of the boa species and are often used to help people overcome their fear of snakes. They never strike at or bite a human under any circumstances but will release a potent musk from their vent if they feel threatened.
Rubber boas are carnivores. They mainly feed on young mammals such as shrews, voles, mice, etc. Rubber boas may also prey on snake eggs, lizard eggs, lizards, young birds, young bats, and there have even been instances of them eating other snakes.
Rubber boas mate shortly after reemergence from hibernation in the spring and young are born anywhere from August to November later that year. They are viviparous (give birth to live young) and can have up to 9 young per year, but many females will only reproduce every four years. The gestation period lasts around 5 months and during this time females are often seen basking in the sun. The young are born fully-developed and are typically 19-23 cm (7.5-9.1 in) long. Females usually become reproductively mature at 4 to 5 years of age while males reach maturity when they are 3 or 4 years old.
There are no major threats to Rubber boa at present.
According to IUCN, the Rubber boa is locally common and widespread throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.