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Northern Eyelash-Boa (Trachyboa boulengeri)
Reptiles of Ecuador | Serpentes | Tropidophiidae | Trachyboa boulengeri
English common names: Northern Eyelash-Boa, Rough-scaled Boa.
Spanish common names: Pudridora del Chocó, dormilona, boa enana áspera, boa de pestañas, boa pigmea de Boulenger.
Recognition: ♂♂ 34.8 cmMaximum distance from the snout to the tip of the tail. ♀♀ 35 cmMaximum distance from the snout to the tip of the tail.. The Northern Eyelash-Boa (Trachyboa boulengeri) is one of the most distinct snakes of the Chocó rainforest.1 It looks like a stick, it has a stout body, dragon-like face, extremely short tail, and small scaly “eyelashes.” The dorsal scales are strongly keeled, which gives the snake a rugose appearance, and are arranged in 29–33 rows at mid-body.2,3 The eyes are deep reddish-brown with cream speckles. The belly is pinkish brown with black blotches. Adults have an essentially patternless brown dorsum, whereas juveniles have light cream blotches interspersed with black ones.1 In its area of distribution, T. boulengeri is unmistakable. However, in the southern part of its distribution, its range may overlap slightly with the one of T. gularis, another similar dwarf boa that differs from the northern species by lacking scaly eyelashes.1,4
Figure 1: Individuals of Trachyboa boulengeri from Canandé Reserve () and FCAT Reserve (), Esmeraldas province, Ecuador. ad=adult, j=juvenile.
Natural history: Locally frequentRecorded weekly in densities below five individuals per locality.. Trachyboa boulengeri is a semi-aquatic and terrestrial1 snake that inhabits old-growth to moderately disturbed evergreen lowland and foothill forests, although individuals occasionally venture into plantations and pastures near the forest border.5 Northern Eyelash-Boas are nocturnal. At dusk, they emerge from their diurnal hideouts, and forage slowly (less than 0.2–0.5 cm/s or slightly faster than a snail)1 on the forest floor besides bodies of water, usually along streams, but also temporary ponds and lagoons.5 Active individuals are often spotted motionless on damp leaf-litter, mud, rocks, trunks, and even on twigs and leaves 30–60 cm above the ground.5 They are good, fast swimmers, but the majority of their time in the water is spent waiting motionless with the head submerged in ambush pasture.6 Their activity seems to be higher during drizzly or rainy nights,1,5 but they may also remain in the same resting place for days or even weeks.1 During the day, Northern Eyelash-Boas hide under rocks, rotten logs, and in leaf-litter.5
Individuals of Trachyboa boulengeri are ambush predators. They wait for prey to pass by and then grab it with unexpected speed.1,6 The snakes wrap the prey in several nooses and strangle it for 30–120 minutes, whereas other times they consume it without strangling it.1,6 Their diet includes fish, frogs (such as Leptodacylus melanonotus), and tadpoles.1,5,6 One T. boulengeri female from Panamá contained six developed embryos,7 whereas two females from Ecuador “gave birth” (the eggs hatched within the mother or shortly after being laid) to six live young, each.1,8 The neonates measured 12.6–12.8 cm in total length.1
Northern Eyelash-Boas rely primarily on their slow movements and uncanny resemblance of a stick to go unnoticed.They are calm, peaceful snakes.1 If grabbed, some individuals become rigid and immobile, others roll into a tight ball, produce a musky and distasteful cloacal secretion, and yet others submerge completely for a short time.1,5
Conservation: Least Concern Believed to be safe from extinction given current circumstances..9 Trachyboa boulengeri is listed in this category because the species is widely distributed throughout the Chocó rainforest (especially in areas that have not been heavily affected by deforestation, like the Colombian Pacific coast) and is considered to be facing no major immediate extinction threats.9 The most important threat to the long-term survival of the species is large-scale deforestation. It estimated that, in Ecuador, ~62% of the habitat of T. boulengeri has been destroyed.10 Northern Eyelash-Boas also suffer from direct killing as they are often mistaken with venomous snakes.5 They also have been a target of the illegal trade of wildlife for decades,1 and are considered a highly-priced rarity among collectors in Europe and the United States.
Distribution: Trachyboa boulengeri is native to the Chocoan lowlands and adjacent mountain foothills from northwestern Ecuador, through western Colombia, to eastern Panamá. In Ecuador, the species occurs at elevations between 5 and 902 m (Fig. 2).
Figure 2: Distribution of Trachyboa boulengeri in Ecuador. See Appendix 1 for a complete list of the presence localities included in the map.
Etymology: The name Trachyboa, which comes from the Greek words trachys (meaning “rough”) and boa (a large serpent),11 refers to the rugose dorsal appearance of snakes in this genus. The specific epithet boulengeri honors Belgian-British zoologist George Albert Boulenger (1858–1937), who described and gave scientific names to thousands of animal species, including 598 reptiles that are recognized as valid species today.12
See it in the wild: Northern Eyelash-Boas can be seen with ~5–10% certainty along bodies of water in well-preserved forested areas throughout their area of distribution. In Ecuador, they are particularly frequent in Canandé Reserve and Bilsa Biological Reserve. The snakes are more easily located at night and by walking along streams when the ambient humidity is high.
Special thanks to Jordi David Rivera Albuja for symbolically adopting the Northern Eyelash-Boa and helping bring the Reptiles of Ecuador book project to life.
Click here to adopt a species.
Author: Alejandro ArteagaaAffiliation: Khamai Foundation, Quito, Ecuador.
Photographer: Jose VieiraaAffiliation: Tropical Herping (TH), Quito, Ecuador.,bAffiliation: ExSitu, Quito, Ecuador.
How to cite? Arteaga A (2021) Northern Eyelash-Boa (Trachyboa boulengeri). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: www.reptilesofecuador.com. DOI: 10.47051/FAIK2894
Literature cited:
- Lehmann HD (1969) Beobachtungen bei der Haltung und Aufzucht von Trachyboa boulengeri (Serpentes, Boidae). Salamandra 6: 32–42.
- Peters JA, Donoso-Barros B (1970) Catalogue of Neotropical Squamata: part I, snakes. Bulletin of the United States National Museum, Washington, D.C., 347 pp.
- MECN (2010) Serie herpetofauna del Ecuador: El Chocó esmeraldeño. Museo Ecuatoriano de Ciencias Naturales, Quito, 232 pp.
- Peters WCH (1860) Eine neue Gattung von Riesenschlangen vor, welche von einem gebornen Preussen, Hrn. Carl Reiss, in Guayaquil nebst mehreren anderen werthvollen Naturalien dem zoologischen Museum zugesandt worden ist. Monatsberichte der Königlichen Preussische Akademie des Wissenschaften zu Berlin 1860: 200–202.
- Field notes, Reptiles of Ecuador book project.
- Dwyer Q, Arteaga A, Barrio-Amorós CL, Fagle A (2018) Trachyboa boulengeri. Diet. Herpetological Review 49: 359–360.
- Barbour T (1937) Ovoviviparity in Trachyboa. Copeia 1937: 139.
- Unpublished data by Ernesto Arbeláez.
- Ibáñez R, Jaramillo C, Rivas G, Gutiérrez-Cárdenas P, Yánez-Muñoz M, Cisneros-Heredia DF (2019) Trachyboa boulengeri. The IUCN Red List of threatened species. Available from: www.iucnredlist.org. DOI: 10.2305/IUCN.UK.2019-2.RLTS.T203214A2762365.en
- MAE (2012) Línea base de deforestación del Ecuador continental. Ministerio del Ambiente del Ecuador, Quito, 30 pp.
- Brown RW (1956) Composition of scientific words. Smithsonian Books, Washington D.C., 882 pp.
- Uetz P, Freed P, Hošek J (2021) The reptile database. Available from: www.reptile-database.org
Appendix 1: Locality data used to create the distribution map of Trachyboa boulengeri in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used.
| Country | Province | Locality | Source |
| Colombia | Nariño | Carretera a Tumaco | IAvH-R-1501 |
| Colombia | Nariño | Milagros–Teheran | JCC 2693 |
| Colombia | Nariño | Reserva Natural El Pangán | Photo by Hernán Arias |
| Colombia | Nariño | Universidad Nacional de Colombia, Sede Nariño | Pinto-Erazo et al. 2020 |
| Ecuador | Carchi | Destacamento Militar | MECN 8073 |
| Ecuador | Carchi | Río San Juan | MECN 6739 |
| Ecuador | Carchi | Tobar Donoso | iNaturalist |
| Ecuador | Cotopaxi | 40 km E of Quevedo | USNM 142597 |
| Ecuador | Cotopaxi | El Jardín de los Sueños | Photo by Christophe Pellet |
| Ecuador | Cotopaxi | Yakusinchi | Photo by Jane Sloan |
| Ecuador | Esmeraldas | Bilsa Biological Reserve | Ortega-Andrade et al. 2010 |
| Ecuador | Esmeraldas | Bosque Protector La Chiquita | Online multimedia |
| Ecuador | Esmeraldas | Bosque Protector Otokiki | Elicio Tapia, pers. comm. |
| Ecuador | Esmeraldas | Calle Mansa | Morales 2004 |
| Ecuador | Esmeraldas | Canandé Reserve | This work |
| Ecuador | Esmeraldas | Centro de Fauna Silvestre James Brown | Photo by Salvador Palacios |
| Ecuador | Esmeraldas | Chapulá | Morales 2004 |
| Ecuador | Esmeraldas | Charco Vicente | Morales 2004 |
| Ecuador | Esmeraldas | Durango | Morley Read |
| Ecuador | Esmeraldas | Durango, 4 km N of | Online multimedia |
| Ecuador | Esmeraldas | Estero Pote | QCAZ 10704 |
| Ecuador | Esmeraldas | FCAT Reserve | iNaturalist |
| Ecuador | Esmeraldas | Golondrinas | Cisneros-Heredia 2004 |
| Ecuador | Esmeraldas | Itapoa Reserve | This work |
| Ecuador | Esmeraldas | km 17 on Lita–Alto Tambo road | Cisneros-Heredia 2004 |
| Ecuador | Esmeraldas | Las Mareas | iNaturalist |
| Ecuador | Esmeraldas | Lote Salvadores | This work |
| Ecuador | Esmeraldas | Pajonal | Morales 2004 |
| Ecuador | Esmeraldas | Playa de Oro | iNaturalist |
| Ecuador | Esmeraldas | Río Hoja Blanca | This work |
| Ecuador | Esmeraldas | San Francisco del Cabo | MECN 3500 |
| Ecuador | Esmeraldas | Tesoro Escondido Reserve | iNaturalist |
| Ecuador | Esmeraldas | Tundaloma Lodge | This work |
| Ecuador | Esmeraldas | Verdecanandé | This work |
| Ecuador | Esmeraldas | Vida Rosero Reserve | This work |
| Ecuador | Esmeraldas | Zapallo Grande | Cisneros-Heredia 2004 |
| Ecuador | Imbabura | km 5 on Lita–Ibarra road | Cisneros-Heredia 2004 |
| Ecuador | Los Ríos | Centro Científico Río Palenque | KU 152601 |
| Ecuador | Los Ríos | Quevedo | USNM 60518 |
| Ecuador | Manabí | La Crespa | iNaturalist |
| Ecuador | Manabí | Maicito | MHNG 1326.092 |
| Ecuador | Manabí | Quiebra Cabeza | Photo by Carlos Robles |
| Ecuador | Pichincha | El Chalpi–Saguangal | Yánez-Muñoz et al. 2009 |
| Ecuador | Pichincha | Lower Mashpi | This work |
| Ecuador | Pichincha | Mashpi Reserve | iNaturalist |
| Ecuador | Pichincha | Mindo, 20 km W of | USNM 204103 |
| Ecuador | Pichincha | Nuevo Mundo | MECN 2240 |
| Ecuador | Pichincha | Puerto Quito | MHNG 2284.024 |
| Ecuador | Pichincha | Rainforest Monterreal | iNaturalist |
| Ecuador | Pichincha | Rancho Suamox | Photo by Rafael Ferro |
| Ecuador | Pichincha | Río Blanco | USNM 204104 |
| Ecuador | Pichincha | Selva Virgen | This work |
| Ecuador | Pichincha | Río Silanche Bird Sancturary | This work |
| Ecuador | Santo Domingo de los Tsáchilas | 5 km W La Florida | KU 218411 |
| Ecuador | Santo Domingo de los Tsáchilas | Bosque Protector La Perla | This work |
| Ecuador | Santo Domingo de los Tsáchilas | Finca Gloria | Photo by Regdy Vera |