Emerald Tree Boa

About the emerald tree boa

The emerald tree boa is a boa species found in the rainforests of South America. Like all boas, it is nonvenomous, and international trade in the species is controlled under CITES Appendix II. Since 2009, a closely related population has been split off as its own species, Corallus batesii, though the two are often discussed together.

Most adults grow to about 6 feet (1.8 m) in length, though specimens from the Amazon River basin tend to grow largest, reaching 7 to 9 feet (2.1–2.7 m), and are noticeably more docile than their northern relatives. The species has highly developed front teeth, proportionately larger than those of almost any other nonvenomous snake. Its coloring is among the most distinctive of South American snakes: an emerald green body marked with an irregular, broken white "lightning bolt" stripe down the back, and a yellow belly. Juveniles look nothing like the adults — they hatch in shades of light or dark orange or brick-red and only turn green after 9 to 12 months, in a color change also seen in the unrelated green tree python of Southeast Asia and Australia.

The resemblance between the emerald tree boa and the green tree python is a well-known case of convergent evolution: the two species are only distantly related, but head scalation and the placement of heat-sensing pits around the mouth reveal the difference. Within the emerald tree boa's own range, populations vary too. Snout scales are smaller in Amazon Basin snakes than in those from Guyana, Suriname, Venezuela, Bolivia and French Guiana — sometimes called "Guyana Shield" or "Northern" emerald tree boas — and hybrids between the two forms are known to occur where their ranges meet.

Behavior and diet

The emerald tree boa's diet consists primarily of small mammals such as rodents and marsupials, a finding that overturned an older assumption that birds made up most of its diet. It will also take smaller bird species, lizards and frogs; juveniles and newborns in particular are known to feed on small lizards and frogs, including glass frogs.

Because of an extremely slow metabolism, the species feeds much less often than ground-dwelling snakes, and meals can be spaced months apart.

Reproduction follows the ovoviviparous pattern typical of boas: females retain eggs internally and give birth to live young rather than laying eggs. A litter averages between 6 and 14 young, though larger litters are possible; anything beyond that range is considered extremely rare. Newborns emerge in the brick-red to orange coloring described above and spend roughly the next year transitioning to the full emerald-green of the adult.

Range and habitat

The emerald tree boa is found across the northern reaches of South America, including Colombia, Brazil, and a band running from Venezuela through Suriname and the Guianas — the region known as the Guiana Shield. The related Amazon Basin form occupies the basin of the Amazon River itself, spanning southern Suriname, southern Guyana, southern Venezuela, Colombia, Peru and Brazil and the surrounding jungle.

Across this range, the species is found in rainforest habitat. Coloring and scale details vary somewhat by locality — snakes from the southern end of the range in Peru tend to run darker.

Conservation status

The emerald tree boa is classified as Least Concern (LC). International trade in the species is controlled under CITES Appendix II.