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Charina bottaebottae

By Jade Collins

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. ("Southern Rubber Boa", 2013; "Northern Rubber Boa - Charina bottae", 2023)

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. ("Southern Rubber Boa", 2013; "Northern Rubber Boa - Charina bottae", 2023)

  • Aquatic Biomes
  • rivers and streams
  • Range elevation
    0 to 3050 m
    0.00 to 10006.56 ft
  • Average elevation
    2000 m
    6561.68 ft

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. (Chappell and Ellis, 1987; Hoyer and Stewart, 2000a; "Southern Rubber Boa", 2013; "Northern Rubber Boa", 2023a; "Northern Rubber Boa - Charina bottae", 2023; "Rubber Boa Care Sheet", 2022; Rodrı́guez-Robles, et al., 2001)

  • Sexual Dimorphism
  • female larger
  • Range mass
    70 to 200 g
    2.47 to 7.05 oz
  • Range length
    35 to 84 cm
    13.78 to 33.07 in
  • Average basal metabolic rate
    0.63 cm3.O2/g/hr

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. ("Rubber Boa Care Sheet", 2022)

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. ("Rubber Boa", 2023; "Rubber Boa Care Sheet", 2022)

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. ("Rubber Boa", 2023; "Northern Rubber Boa", 2023b)

  • Breeding interval
    About once every three to four years
  • Breeding season
    Spring
  • Range number of offspring
    1 to 9
  • Average number of offspring
    2-5
  • Average gestation period
    5 months
  • Range time to independence
    6 to 8 months
  • Range age at sexual or reproductive maturity (female)
    3 to 4 years
  • Range age at sexual or reproductive maturity (male)
    2 to 3 years

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. ("Northern Rubber Boa", 2023b; Hoyer and Stewart, 2000b)

  • Parental Investment
  • 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. ("Northern Rubber Boa", 2023a; "Northern Rubber Boa - Charina bottae", 2023; "Rubber Boa Care Sheet", 2022)

  • Range lifespan
    Status: wild
    40 to 50 years
  • Range lifespan
    Status: captivity
    7 to 30 years
  • Typical lifespan
    Status: captivity
    20 to 30 years

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. ("Rubber Boa", 2023; "Northern Rubber Boa", 2023b; Dorcas and Peterson, 1998; Field Guides, 2023; "Southern Rubber Boa", 2013; "Northern Rubber Boa", 2023a; Zhang, et al., 2008)

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. ("Rubber Boa", 2023)

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. (Kidadl, et al., 2022; "Northern Rubber Boa", 2023a)

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. ("Rubber Boa", 2023; "Northern Rubber Boa", 2023b; Hoyer and Stewart, 2000b)

  • Primary Diet
  • 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). ("Rubber Boa", 2023; "Southern Rubber Boa", 2013; "Rubber Boa Care Sheet", 2022)

  • Anti-predator Adaptations
  • 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. ("Rubber Boa", 2023; "Southern Rubber Boa", 2013; "Rubber Boa Care Sheet", 2022)

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. ("Northern Rubber Boa", 2023a; "Rubber Boa Care Sheet", 2022)

  • Positive Impacts
  • pet trade
  • controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of Charina bottae on humans. ("Northern Rubber Boa - Charina bottae", 2023)

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. ("Rubber Boa", 2023; "Southern Rubber Boa", 2013; "Northern Rubber Boa", 2023a)

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". ("Northern Rubber Boa - Charina bottae", 2023; Stewart, 1977)

Contributors

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

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

ovoviviparous

reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

soil aeration

digs and breaks up soil so air and water can get in

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

young precocial

young are relatively well-developed when born

References

2023. "Northern Rubber Boa - Charina bottae" (On-line). California Herps. Accessed February 12, 2023 at https://californiaherps.com/snakes/pages/c.bottae.html.

Burke Museum. 2023. "Northern Rubber Boa" (On-line). Burke Museum. Accessed March 02, 2023 at https://www.burkemuseum.org/collections-and-research/biology/herpetology/amphibians-reptiles-washington/northern-rubber-boa.

Nevada Department of Wildlife. 2023. "Northern Rubber Boa" (On-line). Nevada Department of Wildlife. Accessed February 05, 2023 at https://www.ndow.org/species/northern-rubber-boa/#.

Reptiles Cove. 2022. "Rubber Boa Care Sheet" (On-line). Reptiles Cove. Accessed February 26, 2023 at https://reptilescove.com/care/snakes/rubber-boa.

Animalia. 2023. "Rubber Boa" (On-line). Animalia. Accessed February 16, 2023 at https://animalia.bio/rubber-boa?taxonomy=986.

Los Padres ForestWatch, Inc. 2013. "Southern Rubber Boa" (On-line). Accessed February 05, 2023 at https://lpfw.org/wp-content/uploads/pdf/SouthernRubberBoa.pdf.

Chappell, M., T. Ellis. 1987. Resting metabolic rates in boid snakes: allometric relationships and temperature effects. Journal of Comparative Physiology B, 157: 227–235. Accessed February 26, 2023 at https://doi.org/10.1007/BF00692367.

Dorcas, M., C. Peterson. 1998. Daily Body Temperature Variation in Free-Ranging Rubber Boas. Herpetologica, 54/1: 88-103. Accessed February 12, 2023 at https://www.jstor.org/stable/3893400.

Dorcas, M., C. Peterson, M. Flint. 1997. The Thermal Biology of Digestion in Rubber Boas (Charina bottae): Physiology, Behavior, and Environmental Constraints. The University of Chicago Press Journals, 70/3. Accessed February 05, 2023 at https://www.journals.uchicago.edu/doi/10.1086/639601#pane-pcw-related.

Field Guides, M. 2023. "Northern Rubber Boa - Charina bottae" (On-line). mt.gov. Accessed March 10, 2023 at https://fieldguide.mt.gov/speciesDetail.aspx?elcode=arada01010.

Hoyer, R., G. Stewart. 2000. Biology of the Rubber Boa (Charina bottae), with Emphasis on C. b. umbratica. Part I: Capture, Size, Sexual Dimorphism, and Reproduction. Journal of Herpetology, 34: 348-354. Accessed February 05, 2023 at https://www.jstor.org/stable/1565355?origin=crossref#metadata_info_tab_contents.

Hoyer, R., G. Stewart. 2000. Biology of the Rubber Boa (Charina bottae), with Emphasis on C. b. umbratica. Part II: Diet, Antagonists, and Predators. Journal of Herpetology, 34: 354-360. Accessed February 05, 2023 at https://www.jstor.org/stable/1565356?origin=crossref&seq=3#metadata_info_tab_contents.

Kidadl, T., M. Kochhar, D. Gupta. 2022. "Fun Rubber Boa Facts For Kids" (On-line). Kidadl. Accessed March 10, 2023 at https://kidadl.com/facts/animals/rubber-boa-facts.

Rodrı́guez-Robles, J., G. Stewart, T. Papenfuss. 2001. Mitochondrial DNA-Based Phylogeography of North American Rubber Boas, Charina bottae (Serpentes: Boidae). Molecular Phylogenetics and Evolution, 18/2: 227-237. Accessed February 05, 2023 at https://www.sciencedirect.com/science/article/pii/S1055790300908868?via%3Dihub.

Stewart, G. 1977. Charina, C. bottae. Catalogue of American Amphibians and Reptiles (CAAR), 1: 205-206. Accessed February 12, 2023 at http://hdl.handle.net/2152/45131.

Zhang, Y., M. Westfall, K. Hermes, M. Dorcas. 2008. Physiological and behavioral control of heating and cooling rates in rubber boas, Charina bottae. Journal of Thermal Biology, 33/1: 7-11. Accessed February 05, 2023 at https://www.sciencedirect.com/science/article/pii/S0306456507000903?via%3Dihub.

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