Imantodes cenchoaBlunthead Tree Snake

Last updated:

Geographic Range

Blunthead tree snakes are found in Central America (eastern Mexico to Panama) and throughout the coastal countries of northern and western South America (Venezuela, Columbia, Ecuador, Peru, Bolivia, French Guiana, Brazil, Paraguay, Peru, and Argentina), as well as the islands of Trinidad and Tobago. (Hallermann, 2012; Henderson and Knickerson, 1976)

Habitat

Blunthead tree snakes occupy primary and secondary growth forests as well as plantation areas in lowland moist and wet forests. They also occur in premontane wet forests and rainforests, as well as lower montane wetforests and rainforests. These snakes are arborial, often found in low vegetation including coffee trees and bromeliads, and can be found up to 2000 meters above sea level (most often 1500 meters or below). ("Blunt-headed Tree Snake: Imantodes Cenchoa", 2012; Zug, et al., 1979)

  • Range elevation
    0 to 2000 m
    0.00 to 6561.68 ft

Physical Description

Blunthead tree snakes have long, slim bodies and very thin necks, with large heads. Their eyes, which have vertical pupils, account for approximately 25% of the length of the head and protrude from the side of the head, enabling the animal to look downward. Snout to vent length for this species is generally around 800 millimeters, but can reach over 901 millimeters; total body length can exceed 1 meter. This snake has an adaptive, enlarged middorsal scale row, which provides stability when climbing. Blunthead tree snakes are primarily white ventrally and pale brown dorsally. The dorsal surface is overlaid with 29-56 dark brown blotches (the number of dorsal blotches varies across this species' range). These snakes have rear fangs. Northern populations of these snakes exhibit sexual dimorphism, with males having slightly longer tails (southern populations do not share this characteristic). Additionally, in some regions head size is variable between males and females, with females typically having greater head lengths and widths. (Myers, 1982; Pizzatto, et al., 2008; Zug, et al., 1979)

  • Sexual Dimorphism
  • female larger
  • Range length
    232 to 901 mm
    9.13 to 35.47 in
  • Average length
    800 mm
    31.50 in

Development

Young develop in eggs laid by females, nourished by yolk. Eggs average 30.7 mm in length. Juveniles hatch, appearing as small adults (average SVL 279.7 mm), typically from March through August, and grow approximately 3.5 millimeters per week for their first two years of life. After this time, they will typically have achieved sexual maturity. (Zug, et al., 1979)

Reproduction

Mating may occur in this species year round throughout its range, although the mating season may be correlated with the rainy season in some regions. Areas with long rainy seasons tend to produce longer reproductive seasons, whereas areas with shorter rainy seasons call for a much more rapid reproduction and development process. A few instances of mating related male-male fighting have been recorded for this species, both in the Brazilian Amazon and in a Peruvian rainforest. This is particularly notable, as no other record of ritualistic male-male combat has been reported for any other species within the dipsadine clade. One account of such behavior records a male of a mating pair approaching another nearby male and using the anterior portion of his body to force away this potential rival. (Dos Santos-Costa and da Costa Prudente, 2005; Pizzatto, et al., 2008; Zug, et al., 1979)

Blunthead tree snakes generally exhibit continuous reproduction. However, in areas that have seasonal rainfall, egg laying and hatching is found to correlate positively with local wet seasons; for example, in Guatemala and Mexico, eggs are laid in June and July, with hatchlings appearing in July and August, corresponding with the wet seasons of these countries. In Brazilian rainforests, continuous reproduction occurs; vitellogenesis (yolk production) takes place from September through November or December, eggs are laid from November through January, and hatchlings appear from March through August. These snakes are oviparous. An average clutch will contain 2-3 eggs; clutch size is dependent on factors such as female body size, habitat and feeding habits. Female blunthead tree snakes reach sexual maturity at about 620 mm SVL; males mature around the same size, typically about two years after hatching. (Pizzatto, et al., 2008; Stuart, 1948; Zug, et al., 1979)

  • Breeding interval
    Blunthead tree snakes may breed multiple times throughout the year, depending on the region where they live.
  • Breeding season
    Some populations of blunthead tree snakes breed year round while other have breeding seasons correlating to rainy seasons.
  • Range number of offspring
    1 to 3
  • Average age at sexual or reproductive maturity (female)
    2 years
  • Average age at sexual or reproductive maturity (male)
    2 years

There is no literature currently available that describes the parental care in these snakes. Brooding is uncommon in all species of snakes apart from those in the family Pythonidae. Therefore, it is a reasonable assumption, as this species is oviparous, that the female most likely leaves her eggs after laying them and that neither the male nor female looks after the hatchlings. (Zug, et al., 2001)

  • Parental Investment
  • no parental involvement

Lifespan/Longevity

No published information exists regarding the average lifespan of these snakes; it is suspected to be highly variable throughout their broad geographical range. (Zug, et al., 1979)

Behavior

Blunthead tree snakes are nocturnal, arboreal snakes. During the day, they may be found resting in a coiled position in shaded bromeliads, between coffee tree leaves, at tree bases, and in leaf litter. They are noted to prefer shaded resting places. At night, these snakes forage, primarily from ground level up to two meters, throughout various forms of dense vegetation (vine tangles, bushes, small trees). This species is fairly active at night and has been found, in captivity, to travel an average of 5-10 meters in 5 minutes. Although arboreal, blunthead tree snakes will readily travel across the forest floor. They tend to be docile and solitary outside of breeding season, and are not known to bite humans. ("Blunt-headed Tree Snake: Imantodes Cenchoa", 2012; Henderson and Knickerson, 1976; Landy, et al., 1966; Myers, 1982; Slevin, 1939; Stuart, 1948; Taylor, 1951; "Blunt-headed Tree Snake: Imantodes Cenchoa", 2012; Henderson and Knickerson, 1976; Landy, et al., 1966; Myers, 1982; Slevin, 1939; Stuart, 1948; Taylor, 1951)

Home Range

These snakes are not known to have a specific home range or to defend territories. (Myers, 1982; Zug, et al., 1979)

Communication and Perception

Apart from male-male combat that may occur during mating, very little is known about intraspecific interactions between individuals. Blunthead tree snakes rely primarily on their binocular vision and vertically slit, protruding eyes to hunt at night. Like all snakes, they have well developed olfactory, tactile, and hearing systems. (Dos Santos-Costa and da Costa Prudente, 2005; Myers, 1982; Zug, et al., 2001)

Food Habits

Blunthead tree snakes forage at night, feeding on small arboreal lizards (primarily anoles, such as Norops capito, Anolis latifrons, Norops limifrons, Norops mariarum, and Norops tropidogaster). In addition to small lizards, these snakes have been known to target adult frogs (such as Craugastor crassidigitus and Craugastor raniformis) as well as frog (Agalychnis callidryas) and reptile eggs. Female blunthead tree snakes from Panama are known to be capable of consuming larger prey, such as Anolis frenatus due to their larger heads, leading to a difference in feeding trends not only regionally but between males and females in this area. (Gutierrez-C and Arredondo-S, 2005; Henderson and Knickerson, 1976; Landy, et al., 1966; Myers, 1982; Stuart, 1948; Zug, et al., 1979)

  • Primary Diet
  • carnivore
    • eats terrestrial vertebrates
    • eats eggs
  • Animal Foods
  • amphibians
  • reptiles
  • eggs

Predation

While no information regarding specific predators of blunthead tree snakes currently exists, main predators of other snakes in Latin America include birds of prey such as laughing falcons (Herpetotheres cachinnans) and crane hawks (Geranospiza caerulescens). These nocturnal snakes hide during the day and their coloration acts as camouflage, helping them to avoid predation. (Campbell and Lamar, 1989)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

These snakes are primarily predators of Anolis lizards and frogs. While no published information exists regarding specific predators of this snake species, it is likely a food source for various bird of prey species. (Asmundsson, et al., 2001; Bursey and Brooks, 2011)

Commensal/Parasitic Species
  • Eimeria cenchoae (Order Eucoccidiorida, Phylum Apicomplexa)
  • Kalicephalus costatus (Order Strongylida, Phylum Nematoda)

Economic Importance for Humans: Positive

No economic benefits to humans from this snake are currently known. Due to their small, thin bodies and general fragility, they are not commonly seen in the pet trade. The general lack of knowledge regarding this species, however, does leave the potential for additional research. (Zug, et al., 1979)

  • Positive Impacts
  • research and education

Economic Importance for Humans: Negative

Although these snakes are venomous, their bite is not particularly harmful to humans. These snakes are typically docile and are well hidden during the day, limiting any potential human interaction. (Costa, et al., 2010; Myers, 1982; Pizzatto, et al., 2008)

  • Negative Impacts
  • injures humans
    • bites or stings

Conservation Status

Blunthead tree snakes have not yet been evaluated by the IUCN and are not considered threatened by any conservation agency. Their cryptic nature and nocturnal habits make population size estimations difficult, though they are known to have low population densities in various areas throughout their large geographical range. (IUCN, 2012; Costa, et al., 2010)

Contributors

Justin Link (author), Michigan Technological University, Amy Schrank (editor), Michigan Technological University, Jeremy Wright (editor), University of Michigan-Ann Arbor.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

arboreal

Referring to an animal that lives in trees; tree-climbing.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

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.

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.

indeterminate growth

Animals with indeterminate growth continue to grow throughout their lives.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

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

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

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

solitary

lives alone

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

venomous

an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

year-round breeding

breeding takes place throughout the year

References

2012. "Blunt-headed Tree Snake: Imantodes Cenchoa" (On-line). Project Noah. Accessed March 10, 2012 at http://www.projectnoah.org/spottings/8508943.

Asmundsson, I., S. Upton, P. Freed. 2001. Five new species of coccidia (Apicomplexa: Eimeriidae) from colubrid snakes of Ecuador. Journal of Parasitology, 87/5: 1077-1081. Accessed February 25, 2013 at http://www.ncbi.nlm.nih.gov/pubmed/11695368.

Aveiro-Lins, G., O. Rocha-Barbosa, M. Salmomao, G. Puorto, M. Loguericio. 2006. Topographical anatomy of the blunthead treesnake, Imantodes cenchoa (Linnaeus, 1758) (Colubridae: Xenodontinae). International Journal of Morphology, 24: 43-48.

Bursey, C., D. Brooks. 2011. Nematode parasites of Costa Rican snakes (Serpentes) with description of a new species of Abbreviata (Physalopteridae). Comparative Parasitology, 78/2: 333-358. Accessed February 26, 2013 at http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1705&context=parasitologyfacpubs&sei-redir=1&referer=http%3A%2F%2Fwww.google.com%2Fsearch%3Fhl%3Den%26source%3Dhp%26q%3Dparasite%2Bimantodes%2Bcenchoa%26gbv%3D2%26oq%3Dparasite%2Bimantodes%2Bcenchoa%26gs_l%3Dheirloom-hp.3...713.8261.0.8427.32.28.3.1.1.0.119.2506.10j15.25.0...0.0...1c.1.oA4YQNAKtxU#search=%22parasite%20imantodes%20cenchoa%22.

Campbell, J., W. Lamar. 1989. Venomous Reptiles of Latin America. Ithaca, New York: Cornell University Press.

Cisneros-Heredia, , F. Diego. 2006. Notes on the distribution and natural history of the bluntheaded vine snake, Imantodes cenchoa, in Ecuador. Herpetological Bulletin, 97: 4-7.

Costa, H., A. Barros, L. Sueiro, R. Feio. 2010. The blunt-headed vine snake, Imantodes cenchoa (Linnaeus, 1758), in Minas Gerais, southeastern Brazil. Biotemas, 23: 173-176.

Dos Santos-Costa, M., A. da Costa Prudente. 2005. Imantodes chenchoa mating. Herpetological Review, 36/3: 324. Accessed February 25, 2013 at http://www.academia.edu/946395/Imantodes_cenchoa_Chunk-headed_snake_Bejuquilla_._Diet.

Gutierrez-C, P., J. Arredondo-S. 2005. Imantodes cenchoa (Chunk-headed Snake, Bejuquilla), Diet. Herpetological Review, 36/3: 324. Accessed February 26, 2013 at http://www.academia.edu/946395/Imantodes_cenchoa_Chunk-headed_snake_Bejuquilla_._Diet.

Hallermann, J. 2012. "Imantodes cenchoa (LINNAEUS, 1758)" (On-line). Zoological Museum Hamburg. Accessed April 11, 2012 at http://reptile-database.reptarium.cz/species?genus=Imantodes&species=cenchoa.

Henderson, R., M. Knickerson. 1976. Observations on the Behavioral Ecology of Three Species of Imantodes (Reptilia, Serpentes, Colubridae). Journal of Herpetology, 10: 205-210.

IUCN, 2012. "The IUCN Red List of Threatened Species" (On-line). Accessed February 26, 2013 at http://www.iucnredlist.org/search.

Landy, M., D. Langebartel, E. Moll, H. Smith. 1966. A collection of snakes from Volcan Tacana, Chiapas, Mexico. Journal of the Ohio Herpetological Society, 5: 93-101.

Myers, C. 1982. Blunt-headed vine snakes (Imantodes) in Panama, including a new species and other revisionary notes. American Museum Novitates, 2738: 1-50. Accessed February 25, 2013 at http://cro.ots.ac.cr/rdmcnfs/datasets/biblioteca/pdfs/nbina-6358.pdf.

Pizzatto, L., M. Cantor, J. De Oliveria, O. Marques, V. Capovilla, M. Martins. 2008. Reproductive ecology of Dipsadine Snakes, with emphasis on South American species. Herpetologica, 64: 168-179.

Slevin, J. 1939. Notes on a collection of reptiles and amphibians from Guatemala, I: Snakes. Proceedings of the California Academy of Sciences, 4th Series, 23: 393-414.

Stuart, L. 1948. The Amphibians and Reptiles of Alta Verapaz, Guatemala. Miscellaneous Publications, Museum of Zoology, University of Michigan, 69: 1-109.

Taylor, E. 1951. A brief review of snakes of Costa Rica. The University of Kansas Science Bulletin, 34: 3-188.

Zug, G., S. Hedges, S. Sunkel. 1979. Variation in reproductive parameters of three neotropical snakes, Coniophanes fissidens, Dipsas catesbyi, and Imantodes cenchoa. Smithsonian Contributions to Zoolology, 300: 1-20. Accessed February 25, 2013 at http://si-pddr.si.edu/jspui/bitstream/10088/5103/2/SCtZ-0300-Lo_res.pdf.

Zug, G., L. Vitt, J. Caldwell. 2001. Herpetology: An Introductory Biology of Amphibians and Reptiles. San Diego, CA: Academic Press.