Greater Ground Snake

Reptiles of Ecuador | Serpentes | Colubridae | Atractus | Atractus major

English common names: Greater Ground Snake, Brown Ground Snake, Big Ground Snake, Major Ground Snake, Large Ground Snake.

Spanish common names: Tierrera grande, culebra tierrera mayor, culebra tierrera café.

Recognition: ♂♂ 53.3 cmMaximum distance from the snout to the tip of the tail. ♀♀ 98.6 cmMaximum distance from the snout to the tip of the tail.. In Ecuador, the Greater Ground Snake (Atractus major) may be recognized by having a round head similar in width to the neck, small eyes, and dorsal pattern consisting of 21–52 pale-edged dark blotches or bands on a pale brown, sepia, or reddish brown ground color.14 Most individuals have a short dark stripe on the neck.4,5 This dorsal pattern is shared with some ground snakes, but A. major is distinguishable by its large size. In Ecuadorian Amazonia, the most similar species is A. pachacamac, which lacks a dark mid-dorsal stripe on the neck.4 Atractus atlas occurs above the known distribution of A. major and also lacks a dark mid-dorsal stripe on the neck.6

Natural history: UncommonUnlikely to be seen more than once every few months. to rareTotal average number of reported observations per locality less than ten.. Atractus major is a semifossorial (living underground and at ground level) snake that inhabits primary and secondary rainforests,7 forest clearings,3 cultivated fields,8 and occasionally rural houses.9 Greater Ground Snakes are normally active at night,5,711 although on occasions also during the day.5,12,13 Snakes of this species may be observed active on the ground, leaf-litter,3 or in some cases concealed beneath rocks, logs, or leaves,3,7,10 and eventually climbing on low vegetation.7,8

Atractus major feeds mainly on giant earthworms3,6,7,13 and occasionally on insects,7,14 which are actively searched for and then captured and swallowed whole.5 Snakes of the genus Atractus have a small mouth aperture angle, which is typical in snakes dwelling underground that feed on small prey.15,16 However, Greater Ground Snakes have a wide mouth aperture angle, like surface-dwelling snakes that feed on large prey.6 A wide mouth aperture angle presumably facilitates the ingestion of giant earthworms.

Only two internal parasites are known in Atractus major; both infect the lungs.17 These are the roundworm Serpentirhabdias atracti and the fluke Glossidiella peruensis.17,18 Generally, these type of parasites cause lesions in the lungs.19,20 Although the real effect in snakes is unknown,20 they presumably reduce the aptitude of infected individuals. On the other hand, in wild specimens from Ecuador, parasites have not been detected in the blood.21

The defensive behavior of Greater Ground Snakes consist mainly of trying to flee, flatten the body to appear larger, or hide the head under body coils.7 Also, when an individual is handled, it can push its head7 or poke its tail10 against the observer's hand. In addition, snakes of this species use camouflage as visual defense behavior, either to hide or mimic venomous snakes.22 The only known predators of Atractus major are the Aquatic Coralsnake (Micrurus surinamensis)10 and the Black-necked Coralsnake (Micrurus obscurus).23 However, other Amazonian snakes species that feed on ground snakes7 can probably also feed on A. major. In some parts the Amazon, the hatching of clutches of this species coincides with periods of low rainfall.7 Females containing 3–12 eggs have been found,24 but the real clutch size is unknown.

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Conservation: Least Concern.25 Atractus major is listed in this category because the species has a large distribution, use a wide range of habitat types, occurs in protected areas, and lacks major immediate extinction threats.25 The impact of human activities on ecuadorian populations of A. major is not clear, however, there are records of traffic mortality.26

Distribution: Atractus major is native to an estimated ~403,448 km2 area throughout the Amazon basin and adjacent foothills of the Andes in Bolivia, Brazil, Colombia, Ecuador, Peru, and Venezuela.27

Distribution of Atractus major in Ecuador

Etymology: The name Atractus, which is a latinization of the Greek word άτρακτος (meaning “spindle”),2830 probably refers to the fact that snakes of this genus have a uniform width throughout the body and a narrow tail, resembling an antique spindle used to spin fibers. The specific epithet major is a Latin word meaning “greater.” It probably refers to the comparatively large body size of this species.24

See it in the wild: Greater Ground Snakes can be seen with ~1–4% certainty in forested areas throughout Ecuadorian Amazonia. Some of the best localities to find snakes of this species are: Yasuní Scientific Station, Tiputini Biodiversity Station, Jatun Sacha Biological Reserve, Tamandúa Ecological Reserve, Shiripuno Lodge, Copalinga Reseve, and Sani Lodge. The snakes may be located by scanning the forest floor and leaf-litter along trails at night.

Authors: Duvan ZambranoaAffiliation: Universidad del Tolima, Ibagué, Colombia. and Alejandro ArteagabAffiliation: Tropical Herping (TH), Quito, Ecuador.

Photographers: Jose VieirabAffiliation: Tropical Herping (TH), Quito, Ecuador.,dAffiliation: ExSitu, Quito, Ecuador., Frank Pichardo,bAffiliation: Tropical Herping (TH), Quito, Ecuador. and Sebastián Di DoménicodAffiliation: Keeping Nature, Bogotá, Colombia.

How to cite? Zambrano D, Arteaga A (2020) Atractus major. In: Arteaga A, Bustamante L, Vieira J, Guayasamin JM (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from:

Literature cited:

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  10. Field notes, Reptiles of Ecuador book project.
  11. Natera-Mumaw M, Esqueda-González LF, Castelaín-Fernández M (2015) Atlas serpientes de Venezuela. Dimacofi Negocios Avanzados S.A., Santiago de Chile, 456 pp.
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  17. Huancachoque E, Sáez G, Cruces CL, Mendoza C, Luque JL, Chero JD (2020) Glossidiella peruensis sp. nov., a new digenean (Plagiorchiida: Plagiorchiidae) from the lung of the brown ground snake Atractus major (Serpentes: Dipsadidae) from Peru. Zoologia 37: e38837. DOI: 10.3897/zoologia.37.e38837
  18. Kuzmin Y, de Vasconcelos Melo FT, dos Santos JN (2014) A new species of Serpentirhabdias Tkach, Kuzmin & Snyder, 2014 (Nematoda: Rhabdiasidae) parasitic in the brown ground snake Atractus major Boulenger (Reptilia: Serpentes: Dipsadidae) in Brazil. Systematic Parasitology 89: 101–106. DOI: 10.1007/s11230-014-9520-5
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  21. Medrano-Tupiza E, Morales-Arciniega S, Santander-Parra S, Núñez-Naranjo L, Puga-Torres B (2017) Absence of hemoparasites in wildlife snakes, located in the ecological reserves Cota 70, Cotacachi-Cayapas and Sumaco-Napo-Galeras in Ecuador. Research in Zoology 7: 7–10. DOI: 10.5923/j.zoology.20170701.02
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