Northern Rubber Boa

Charina bottae

Description

Total length 37-84 cm (14-33 in).[1] A medium-sized, thick-bodied snake with a small head and truncated tail. The dorsal surface is patternless and ranges from olive green through various shades of brown in adults,[2] to pinkish[3] or orange in neonates. Ventral coloration is typically golden orange to cream and may have darker blotches.[4] The body is covered in small, smooth scales[1], which combined with the deep folds in the skin that appear when the snake is contorted give the animal its unique “rubbery” appearance and feel. The head is blunt with a nearly indistinguishable neck, and the eyes are small with elliptical pupils.[3] Males are generally shorter than females and have a small spur on each side of the vent; the spurs on females are miniscule or absent.[3]

Similar Species

Other Common Names

Two-headed Snake[2][3]

Habitat

The Northern Rubber Boa is found in a wide variety of habitats from sea level to over 2800 m (9200 ft), including damp coniferous forest, open woodlands, grassy meadows,[1] deserts,[3] and chaparral. Preferred microhabitats tend to be humid, and Northern Rubber Boas may be found in rock crevices, rotting logs, leaf litter, and under surface debris such as rocks,[3] boards, or corrugated metal.[6]

Natural History

Seldom seen active on the ground’s surface during the day, Charina bottae is primarily nocturnal and fossorial in its habits.[1] These behavior patterns lead many to believe the species is uncommon or rare, when in fact it is often abundant in the correct habitat.[3] While the stout body and chisel-like head indicate the Northern Rubber Boa is a skilled burrower and spends the majority of its time underground, they are also known to occasionally climb bushes and trees.[1]

Northern Rubber Boas brumate during the coldest periods of the year, emerging in February or March and retreating again around November in most areas. They are often found active at cooler temperatures than most other species of snake, with some individuals found with body temperatures of under 10°C (50°F).[3] Charina bottae will often bask by hiding under flat surface objects, and it is not uncommon to find more than one boa utilizing the same piece of cover to warm up. During hot weather, Northern Rubber Boas will move deeper underground to cooler and damper burrows, but they do not enter a period of dormancy during the summer.[7]

Docile and slow-moving snakes, Northern Rubber Boas typically try to escape underground if disturbed[3]. When handled, they usually curl into a ball while hiding their head[1] and may release a foul-smelling musk from their vents to deter the potential predator.[3] These snakes will not bite, even in self-defense. They are an extremely long-lived species, often surviving two or three decades in the wild and even longer in captivity.[7]

Reproduction

Charina bottae is live-bearing and has two to eight young from August to November[3]. Neonates range from 18-23 cm (7-9 in) in length and are often brightly colored.[4]

Diet

The primary prey of the Northern Rubber Boa is nestling rodents; the snake enters the nest and consumes the young mammals while deflecting attacks from the adult with its tail. The body and particularly the tail of the boa is often heavily scarred from this feeding method.[7] This species is also reported to feed on small birds, other snakes, lizards, and salamanders,[3] as well as the eggs of snakes and lizards.[7]

Range

Confined to western North America. The Northern Rubber Boa ranges from southern British Columbia in the north,[8] through most of Washington and Oregon, down to the Tehachapi Mountains in Southern California.[4] Eastward, their range covers all of Idaho, western Montana and Wyoming, northwestern Utah,[2] and northern Nevada[1]. Distribution in many areas tends to be uneven, comprised of many apparently isolated populations.[9]

Conservation

Charina bottae is federally protected in its limited range in Canada,[8] and is also offered protection at the state level in Washington.[7]

Meaning of Scientific Name

Charina
graceful (Latin)[4]
bottae
in honor of explorer Paolo E. Botta[10]

Taxonomic Notes

Not all researchers recognize the validity of the Northern Rubber Boa, synonomizing it with the Southern Rubber Boa (C. umbratica) as the Rubber Boa, Chrina bottae. Others recognize one species of Charina with three subspecies, C. b. bottae, C. b. umbratica, and C. b. utahensis, based on differences in scalation.[7]. Some sources recognize one species with no subspecies.[3]

References

  1. Behler, John L. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, Inc. 1988
  2. Ransom, Jay Ellis. Harper & Row's Complete Field Guide to North American Wildlife. Harper & Row's, Publishers, Inc. 1981
  3. Storm, Robert M. and William P. Leonard. Reptiles of Washington and Oregon. Seattle Audubon Society 1995
  4. Nafis, Gary. “Northern Rubber Boa”. CaliforniaHerps.com 2010. http://www.californiaherps.com/snakes/pages/c.bottae.html
  5. Nafis, Gary. “Southern Rubber Boa”. CaliforniaHerps.com 2009. http://www.californiaherps.com/snakes/pages/c.umbratica.html
  6. Hoyer, Richard F. “Description of a Rubber Boa (Charina bottae) Population from Western Oregon”. Herpetologica Vol. 30, No. 3. 1974. http://www.jstor.org/pss/3891834
  7. Hoyer, Ryan. “Natural History (and other info) of the Rubber Boa”. RubberBoas.com 2001. http://www.rubberboas.com/Content/about.html
  8. Thompson Rivers University. “Reptiles of British Columbia: Rubber Boa”. BCreptiles.ca 2010. http://www.bcreptiles.ca/snakes/rubberboa.htm
  9. Lewke, RE and RK Stroud. “Freeze-branding as a method of marking snakes”. Copeia Vol. 1974, No. 4. 1974. http://www.jstor.org/pss/1442611
  10. Woodland Park Zoo. “Animal Fact Sheets: Rubber Boa”. Zoo.org 2010. http://www.zoo.org/Page.aspx?pid=527

Classification

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