Mountain Snail-Eater

Reptiles of Ecuador | Serpentes | Colubridae | Dipsas | Dipsas oreas

English common names: Mountain Snail-Eater.

Spanish common names: Caracolera montañera.

Recognition: ♂♂ 78.5 cm ♀♀ 82.7 cm. In its area of distribution, the Mountain Snail-Eater (Dipsas oreas) can be identified by lacking a preocular scale and having a grayish or brownish dorsum with 17–30 dark oval to elliptical dorsolateral blotches that form complete bands on the anterior part of the body.1 The Andean Snail-Eater (D. andiana) is similar, but differs from D. oreas by having a clearly defined dark ∩-shaped mark on the back of the head and by having blotches that do not form complete bands on the anterior part of the body. Dipsas jamespetersi and Dipsas oligozonata have a pattern of dorsal crossbands instead of oval or elliptical blotches.

Natural history: Uncommon to locally frequent. Dipsas oreas is a nocturnal snake that inhabits pristine to moderately disturbed humid and dry montane shrublands, evergreen montane forests, cloudforests, and plantations.1,2 Mountain Snail-Eaters are active at night, especially during the rainy season (December–May) or whenever it is raining or drizzling.1 They move actively but slowly at ground level, or on vegetation up to 2.3 m above the ground.1–3 They feed on snails and slugs.1 During the day, snakes of this species rest coiled under rocks, leaf-litter, or in crevices and bromeliads.1 Individuals of D. oreas are harmless to humans; they are extremely docile and never attempt to bite.2 If threatened, individuals may flatten their body, coil into a defensive posture, and expand their head to simulate a triangular shape.1 Aggregations of seven individuals of D. oreas (one female and six males), presumably related to mating, have been reported.1 Females lay clutches of 4–8 eggs in communal nesting sites such as in crevices 5–30 cm underground.4

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Conservation: Near Threatened.5 Dipsas oreas is listed in this category because much of the species' natural habitat has been fragmented and continues to decline in extent and quality.3,5 In Ecuador, we estimate that ~64% of the habitat of this species has been lost. The patches of shrubland and montane forest vegetation where Mountain Snail-Eaters occur are too few, moderately to heavily disturbed, and lack connectivity between them.3 Live individuals of D. oreas are commonly seen dead on roads, which may indicate a high rate of mortality from vehicle traffic.2 We anticipate that D. oreas may qualify for a threatened category in the near future if the species' habitat continues to be degraded.

Distribution: Dipsas oreas is native to the inter-Andean valleys and both slopes of the Andes in southern Ecuador and northern Peru. Although the area of distribution of D. oreas in Ecuador is ~21,246 km2, we estimate that only an area of ~7,660 km2 holds habitat where the species might occur.

Distribution of Dipsas oreas in Ecuador

Etymology: The generic name Dipsas, which comes from the Greek word dipsa (meaning “thirst”),6 probably refers to the fact that the bite of these snakes was believed to cause intense thirst. The specific epithet oreas, which comes from the Greek word oros (meaning “mountain”),6 refers to the distribution of the species.

See it in the wild: Mountain Snail-Eaters can be seen with ~10–30% certainty in Buenaventura Biological Reserve during the rainy season in this area (December–April). They are most easily located by scanning arboreal vegetation after a period of rain.

FAQ

Do snails attract snakes? Yes. Snail-eating snakes follow snails visually or by tracking their scent trail.7

Do snail-eating snakes eat the shell of the snails? They don't. These snakes use specialized muscular contractions of their wedge-like head to extract snails from their shells.7

Author: Alejandro ArteagaaAffiliation: Biodiversity Field Lab, Khamai Foundation, Quito, Ecuador.

Photographers: Jose Vieira,aAffiliation: Tropical Herping (TH), Quito, Ecuador.,bAffiliation: ExSitu, Quito, Ecuador. Alejandro Arteaga,aAffiliation: Tropical Herping (TH), Quito, Ecuador. and Sebastián Di Doménico.

How to cite? Arteaga A (2020) Dipsas oreas. In: Arteaga A, Bustamante L, Vieira J, Guayasamin JM (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: www.reptilesofecuador.com

Literature cited:

  1. Cadle JE (2005) Systematics of snakes in the Dipsas oreas complex (Colubridae: Dipsadinae) in western Ecuador and Peru, with revalidation of D. elegans (Boulenger) and D. ellipsifera (Boulenger). Bulletin of the Museum of Comparative Zoology 158: 67–136.
  2. Field notes, Reptiles of Ecuador book project.
  3. Almendáriz A (2007) Primer registro de Dipsas oreas en la provincia del Azuay, Ecuador. Revista Politécnica 27: 136–137.
  4. Cadle JE, Chuna P (1995) A new lizard of the genus Macropholidus (Teiidae) from a relictual humid forest of northwestern Peru, and notes on Macropholidus ruthveni Noble. Breviora 501: 1–39.
  5. Yánez-Muñoz M, Venegas P, Cisneros-Heredia DF (2017) Dipsas oreas. The IUCN red list of threatened species. Available from: www.iucnredlist.org
  6. Brown RW (1956) Composition of scientific words. Smithsonian Books, Washington D.C., 882 pp.
  7. Sheehy C (2012) Phylogenetic relationships and feeding behavior of Neotropical snail-eating snakes (Dipsadinae, Dipsadini). PhD Thesis, UT Arlington.