Charina bottae

Geographic Range

Charina bottae is found mainly in the northwest region of the United States of America. Their range extends north into southern Canada and south to southern California. They occur as far west as the Pacific coast and as far east as some parts of Montana, Wyoming, and Utah.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

The elevation range of this species can be from sea level to 3,050 m (about 10,000 ft), but they prefer elevations of 1540-2,460 meters (about 5,000-8,000 ft).

Charina bottae is usually found in moist, green environments. They prefer coniferous forests, grassy meadows, and streamsides. Rubber boas prefers deep, nutrient-rich soils with high moisture as they are burrowers. They use rodent burrows, rock outcroppings, fallen logs, and dense duff (decaying leaves and pine needles) for cover. In summer, rubber boas can be found mostly by bodies of water like streams, springs, and rivers. This might indicate that rubber boas need moist soil to thrive, so they can’t inhabit places with low soil moisture. During seasons other than summer, the environment is wet enough for them to live a little farther from bodies of water.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• forest forest
• mountains mountains

• Aquatic Biomes
• rivers and streams

• Other Habitat Features
• riparian riparian

Physical Description

Rubber boas ( Charina bottae ) can grow to be between 35 and 84 cm, however, they usually fall between 38 and 64 cm. Newly hatched individuals are 19 to 23 cm. There are two subspecies: northern ( C. b. bottae ) and southern ( C. b. umbratica ) rubber boas. Southern rubber boas tend to be slightly smaller in size. Northern and southern populations also have a few notable distinctions in scale shape and number. Northern rubber boas tend to have “subtriangle” frontal scales (head scales) that have a convex posterior margin with 42 or more middorsal scale rows and 197 or more ventral scales, whereas southern rubber boas have “subrectangular” frontal scales with straight or barely convex posterior margin, 41 or fewer middorsal scale rows, and 196 or fewer ventral scales. All rubber boas are typically brown to olive green in color on top and yellow to cream on the bottom. They have small, dark eyes with vertical pupils. Rubber boas look and feel like rubber, giving them their name. They have small, smooth scales and wrinkled skin that create this effect. While this snake is usually one solid color without breaks or patterns, sometimes dark spots or mottling can occur on top. This is more common in northern populations. Similarly, dark mottling can occur on the belly but is not common.

The most notable defining feature of rubber boas are their tail. They have a specialized tail that has a thick bulb of bone and looks a lot like their head. When threatened, they curl up and stick their tail out to imitate their head, causing the predator to attack this extremely durable tail instead of their head. Because of this, their tails are usually scarred. This tail is also prehensile, which means it can grasp things. This allows rubber boas to climb shrubs and other small vegetation, as well as swim remarkably well.

• Other Physical Features
• ectothermic ectothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger

Development

Newborns are much like their adult counterparts, only smaller and brighter in color. No metamorphosis is involved in the transition from juvenile to adult for rubber boas. Rubber boas also don’t experience indeterminate growth. Sex is determined by their size in general and the size of their spurs. Females tend to be larger with smaller spurs than males.

Reproduction

Rubber boas seek out mates immediately after they come out of hibernation in spring. It can be inferred that both males and females seek each other out, but this was not explicitly stated. Rubber boas only breed during this time each year. Females can have up to 9 young per year, but it’s more typical for them to give birth only once every three to four years. It has not been stated whether rubber boas mate with the same snakes or different ones every few years. Rubber boas are solitary snakes, aside from breeding season. Their territories can overlap, but they aren’t territorial and don’t interact. No further mating information was available.

• Mating System
• monogamous monogamous

Rubber boas mate in the spring right after they come out of hibernation. The gestation period is about 5 months and the offspring are born in the months August to November. Rubber boas are viviparous (birth live offspring) and they can have up to 9 hatchlings per year, but females tend to only reproduce once every three to four years. Females fast for the duration of their pregnancy and lay in the sun. The clutch of young is about 19-23 cm in length and born fully developed. Female rubber boas reach maturity at around 4-5 years old, while males reach maturity sooner at around 3-4 years old. Young are usually on their own before this, however, as they leave the spring after their first hibernation.

• Key Reproductive Features
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• viviparous viviparous
• ovoviviparous ovoviviparous

Female rubber boas give live birth to a clutch size of around 2-5 young once every three to four years. There are usually more females born than males, however, males tend to outnumber females as adults, suggesting that females have a greater mortality rate than males. The greater number of females in the litter size might be a mechanism to counteract this mortality rate. The gestation period is usually about 5 months and occurs in April right after the rubber boas come out of hibernation. The females tend to be larger and this helps them give birth to large, live young. It also allows them to store extra fat that they use during their gestation period since they fast for the duration of it. Young are born from August to November and captive snakes birth young about 2 weeks earlier. Females invest about half of their own body weight into birthing their young. After birth, the young are protected and given shelter until the spring after their first hibernation when they set off on their own. The young reach maturity later after they leave their parent’s protection. For males, this is around 2-3 years of age, and for females, it is around 3-4 years of age.

• Parental Investment
• precocial precocial
• pre-hatching/birth
  • provisioning
  • protecting
• pre-weaning/fledging
  • provisioning
  • protecting
• pre-independence
  • provisioning
  • protecting

Lifespan/Longevity

Rubber Boas ( Charina bottae ) can live about 7-30 years in captivity, usually on the higher end of around 20-30 years. They can live 40-50 years in the wild. There is no information on common causes of mortality other than drought and habitat loss because of humans, as well as other human activities.

Behavior

Rubber Boas ( Charina bottae ) are a solitary species of snake. They only interact with each other during mating season. Rubber Boa prefer to reside in moist areas and is a burrowing snake. They are mostly nocturnal but are sometimes found sunbathing in open areas during the day. Rubber boas are also slow-moving snakes compared to other similar snakes. They are quite docile and are non-venomous. They don’t strike out at nonprey when threatened. Instead, they prefer to use their tail to trick predators into attacking the hard knob, or to release a strong odor to deter predators. Rubber boas don’t have a social system. They can regulate their temperature and can heat their bodies almost three times as fast as they can cool down. Because of this, rubber boas prefer cooler places and are very good at adapting to cold conditions. They can even heat up their head more than their body in extreme cold in order to protect their brains. Smaller snakes can heat themselves up faster when they are allowed to move around. Otherwise, mass has no effect on a rubber boa’s ability to regulate its temperature. Rubber boas digest best at mild temperatures, while their digestion process slows down at very cold or very warm temperatures. They are most active at temperatures around 14 degrees Celsius - colder than usual for reptiles since they are nocturnal.

• Key Behaviors
• terricolous
• nocturnal nocturnal
• crepuscular crepuscular
• motile motile
• sedentary sedentary
• hibernation hibernation
• solitary solitary

Home Range

Rubber boas ( Charina bottae ) have a small home range and tend to stay in the same place every year unless forced to move by external pressures like predators or losing habitat.

Communication and Perception

Rubber boas ( Charina bottae ) have good night vision as they usually hunt for prey during the night. Even though rubber boas are slow-moving, they are strong because they are boa constrictors, so they use their body to squeeze prey to death. Like other snakes, they have sensing organs in their mouths that help them smell with their tongue. While there is ongoing research, there is no evidence of rubber boas communicating with each other. Similarly, there is no information available about communication during the mating season between mates. Not much more information has been found.

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Rubber boas ( Charina bottae ) is a carnivore and likes to feed on nesting mammals like white-footed mice ( Peromyscus leucopus ), voles ( Microtus ), and shrews ( Soricidae ). They also eat lizard eggs and other snake’s eggs occasionally. Very rarely, rubber boas prey on lizards, small birds and bats, and other snakes. They hunt during the night, but not much other information on hunting habitats is available.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates

• Animal Foods
• birds
• mammals
• reptiles
• eggs

Predation

The juveniles of Charina bottae are protected by their parent until they go out on their own. Rubber boas use their tail as a dummy head to trick predators into attacking the thick bone instead of their head. Rubber boas can also bite and release a musk to deter predators if necessary. They also have coloration that helps them camouflage. When in defense mode, rubber boas have brown on top and cream on their underside. Since they are a secretive and solitary nocturnal species that spend most of their time underground, they are not preyed upon often. When they are, it is by large predators like hawks ( Buteo ), owls ( Strigiformes ), raptors ( Falconiformes ), skunks ( Mephitidae ), raccoons ( Procyon lotor ), coyotes ( Canis latrans ), and cats ( Felis catus ).

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Rubber boas are a solitary species and doesn’t interact with other species or their own outside of predation and mating. They are prey for large hunters that tend to be nocturnal since they spend most of their time underground aside to hunt, which they do at night. These large predators include hawks, owls, raccoons, coyotes, and others. Rubber boas hunt small, nesting animals like mice and shrews. Occasionally, they will eat lizard or snake eggs.

• Ecosystem Impact
• soil aeration soil aeration

Economic Importance for Humans: Positive

Rubber boas are a popular pet and is even over-collected from their natural habitats because of their docile nature. They feed on small nesting animals that might make their homes in human food storage areas. Besides that, rubber boas don't affect the ecosystem in any special way that benefits humans.

• Positive Impacts
• pet trade pet trade
• controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of Charina bottae on humans.

Conservation Status

According to IUCN Red List, the Southern Rubber Boa is vulnerable, but the Northern Rubber Boa is of least concern. The US Federal List did not have the Southern Rubber Boa listed as any status and didn't have the Northern Rubber Boa listed at all. CITES had no information on either of the subspecies. The State of Michigan List had no information on either subspecies. The Southern Rubber Boa is considered a threatened species in the state of California due to habitat loss from human development, water diversion, and soil disturbances. The Northern Rubber Boa is listed as a "Priority Species" and "Unprotected" in the state of Nevada due to drought and overcollection. Population estimates are unknown.

Other Comments

The “bottae” in the scientific name of the rubber boa is to honor Paolo Emilio Botta who collected the rubber boa in the 19th century. Botta was an explorer, archaeologist, and diplomat. The “umbratica” in the scientific name comes from Latin meaning shade or seclusion which fits the rubber boa’s reclusive behavior. The "Charina" comes from the Greek language meaning "graceful".

Additional Links

Encyclopedia of Life

Contributors

Jade Collins (author), Colorado State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

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