Published January 3, 2023. Open access.

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Rainbow Forest-Racer (Dendrophidion clarkii)

Reptiles of Ecuador | Serpentes | Colubridae | Dendrophidion | Dendrophidion clarkii

English common names: Rainbow Forest-Racer, Clark’s Forest-Racer, Green Forest-Racer.

Spanish common names: Corredora selvática arcoíris, corredora verde.

Recognition: ♂♂ 152.1 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=90.9 cm. ♀♀ 155 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=94.2 cm..1 In western Ecuador, the Rainbow Forest-Racer (Dendrophidion clarkii) can be identified from most other snakes by presenting a combination of keeled dorsal scales arranged in 17 rows at mid-body, a black nuchal collar, dark crossbands with embedded pale ocelli, and conspicuously large eyes.1,2 This species presents ontogenetic variation in dorsal coloration (Fig. 1).3 In juveniles the black nuchal collar and reddish tail characteristic of adults is faint or lacking. Similar species in western Ecuador are D. graciliverpa and D. prolixum, but they differ from D. clarkii by lacking a black nuchal collar and dark crossbands with embedded pale ocelli.1

Figure showing variation among individuals of Dendrophidion clarkii

Figure 1: Individuals of Dendrophidion clarkii from Ecuador: Canandé Reserve, Esmeraldas province (); Kapari Lodge, Pichincha province (); Mashpi Lodge, Pichincha province (); and Mindo, Pichincha province (). ad=adult, sa=subadult, j=juvenile.

Natural history: Dendrophidion clarkii is considered to be rareTotal average number of reported observations per locality less than ten. in Costa Rica,4 but is frequentlyRecorded weekly in densities below five individuals per locality. encountered in forested environments in western Ecuador.5 The species occurs in old-growth rainforest as well as in pastures with scattered trees, cacao plantations, banana groves, and deforested areas where some riparian woodland or gallery forest remains.2,3 Snakes of this species are most often seen active at ground level or on low vegetation during the day,1 either basking or actively foraging on the leaf-litter.1,2 At night, they roost on low (less than 1.5 m above the ground) understory vegetation.5 Rainbow Forest-Racers are active hunters having an aglyphous dentition (meaning their teeth lack specialized grooves to deliver venom).1 Therefore, they ingest prey quickly to avoid them from escaping. The diet of D. clarkii includes primarily frogs of the genera Craugastor, Diasporus, and Pristimantis, including P. achatinus6.7 The main defense mechanism of Rainbow Forest-Racers is to flee quickly, they can also strike or shed-off parts of their tail.1 This species is oviparous. One female in Ecuador contained 7 oviductal eggs1 and one nest in Ecuador had 4 eggs.8

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Conservation: Least Concern Believed to be safe from extinction given current circumstances..9,10 Dendrophidion clarkii is listed in this category because the species is widely distributed, especially in areas that have not been heavily affected by deforestation, like the Colombian Pacific coast, and it is unlikely to be declining fast enough to qualify for a more threatened category.9 The most important threat for the long-term survival of some populations is the loss of habitat due to large-scale deforestation.

Distribution: Dendrophidion clarkii is native to the Mesoamerican and Chocoan lowlands from Costa Rica to southwestern of Ecuador. In Ecuador, the species has been recorded at elevations between 18 and 1706 m (Fig. 2).

Distribution of Dendrophidion clarkii in Ecuador

Figure 2: Distribution of Dendrophidion clarkii in Ecuador. See Appendix 1 for a complete list of the presence localities included in the map.

Etymology: The generic name Dendrophidion comes from the Greek words dendron (meaning “tree”) and ophidion (meaning “small snake”).11 The specific epithet clarkii honors American pathologist and researcher Herbert C. Clark (1877–1960), first director of the Gorgas Memorial Laboratory and instigator of the Panamanian snake census, which contributed immensely to knowledge of the snake fauna of Panama.1

See it in the wild: In Ecuador, Rainbow Forest-Racers are spotted at a rate of about once every week in areas having adequate canopy cover. Snakes of this species are particularly common around the Mindo valley, Pichincha province, as well as near the town Chical, Carchi province. Individuals are most easily spotted sleeping on vegetation along water bodies at night, or moving on pastures with scattered trees during sunny days.

Special thanks to Cheryl Vogt for symbolically adopting the Rainbow Forest-Racer and helping bring the Reptiles of Ecuador book project to life.

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Author: Alejandro ArteagaaAffiliation: Khamai Foundation, Quito, Ecuador.

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

How to cite? Arteaga A (2023) Rainbow Forest-Racer (Dendrophidion clarkii). In: Arteaga A, Bustamante L, Vieira J, Guayasamin JM (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: DOI: 10.47051/COND1023

Literature cited:

  1. Cadle JE, Savage JM (2012) Systematics of the Dendrophidion nuchale complex (Serpentes: Colubridae) with the description of a new species from Central America. Zootaxa 3513: 1–50. DOI: 10.11646/zootaxa.3513.1.1
  2. Arteaga A, Bustamante L, Guayasamin JM (2013) The amphibians and reptiles of Mindo. Universidad Tecnológica Indoamérica, Quito, 257 pp.
  3. Lieb CS (1988) Systematic status of the Neotropical snakes Dendrophidion dendrophis and D. nuchalis. Herpetologica 44: 162–175.
  4. Savage JM (2002) The amphibians and reptiles of Costa Rica, a herpetofauna between two continents, between two seas. The University of Chicago Press, Chicago, 934 pp.
  5. Field notes, Reptiles of Ecuador book project.
  6. Matthijs Hollanders, pers. comm.
  7. Leenders T (2019) Reptiles of Costa Rica: a field guide. Cornell University Press, Ithaca, 625 pp.
  8. Photo by Sebastián Vizcarra.
  9. Köhler G, Lamar W (2017) Dendrophidion clarkii. The IUCN red list of threatened species. Available from: DOI: 10.2305/IUCN.UK.2017-2.RLTS.T203288A2763009.en
  10. Morales-Betancourt MA, Lasso CA, Páez VP, Bock BC (2005) Libro rojo de reptiles de Colombia. Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, Bogotá, 257 pp.
  11. Brown RW (1956) Composition of scientific words. Smithsonian Books, Washington D.C., 882 pp.

Appendix 1: Locality data used to create the distribution map of Dendrophidion clarkii in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used.

ColombiaNariñoAltaque, 1 km SE ofiNaturalist
ColombiaNariñoLa GuayacanaAMNH R-123752; Cadle & Savage 2012
ColombiaNariñoReserva Río ÑambíiNaturalist
ColombiaValle del CaucaCampamento Cartón ColombiaFMNH 165567; Cadle & Savage 2012
ColombiaValle del CaucaCisnerosFMNH 43738, 43741; Cadle & Savage 2012
EcuadorBolívarSan Luis de PambiliNaturalist
EcuadorCarchiChicalUSNM 286301; Cadle & Savage 2012
EcuadorCarchiChical–La Primavera roadiNaturalist
EcuadorCarchiChical, 6 km E ofiNaturalist
EcuadorCarchiMaldonadoKU 179499; Cadle & Savage 2012
EcuadorCarchiMaldonado, 1 km N ofiNaturalist
EcuadorCarchiPeñas BlancasQCAZ 4370; examined
EcuadorCarchiSendero AwaYánez-Muñoz 2009
EcuadorChimborazoValle del ChanchánLieb 1988
EcuadorCotopaxiEl Jardín de los SueñosPhoto by Christophe Pellet
EcuadorCotopaxiYakusinchiPhoto by Jane Sloan
EcuadorEsmeraldasAlto Tambo, 3 km SE ofiNaturalist
EcuadorEsmeraldasBilsa Biological ReserveOrtega-Andrade et al. 2010
EcuadorEsmeraldasCachabiBMNH 1901.3.29.28; Cadle & Savage 2012
EcuadorEsmeraldasCanandé Biological ReserveiNaturalist
EcuadorEsmeraldasItapoa ReservePhoto by Rául Nieto
EcuadorEsmeraldasLote RoseroUnpublished photo record; this work
EcuadorEsmeraldasPulúnBMNH 1901.8.3.4.; Cadle & Savage 2012
EcuadorEsmeraldasReserva Tesoro EscondidoiNaturalist
EcuadorEsmeraldasRío SapayoBMNH 1902.7.29.17; Cadle & Savage 2012
EcuadorEsmeraldasSan MateoFMNH 27589; Cadle & Savage 2012
EcuadorImbaburaParambaBMNH; Cadle & Savage 2012
EcuadorImbaburaReserva Los CedrosiNaturalist
EcuadorImbaburaRío ChalguayacuUSNM 237043; Cadle & Savage 2012
EcuadorImbaburaRío GuayllabambaiNaturalist
EcuadorImbaburaVía a García MorenoUSNM 237044; Cadle & Savage 2012
EcuadorLojaAlamorAMNH 22096; Cadle & Savage 2012
EcuadorManabíCerro Pata de PájaroArteaga et al. 2013
EcuadorPichinchaHacienda La HesperiaiNaturalist
EcuadorPichinchaKapari Lodge’s trailsPhotographic record; this work
EcuadorPichinchaMaquipucuna ReserveArteaga et al. 2013
EcuadorPichinchaMashpi LodgeYánez-Muñoz et al. 2009
EcuadorPichinchaMilpeUSNM 237058; Cadle & Savage 2012
EcuadorPichinchaMilpe Bird SanctuaryPhoto record by Jose Vieira
EcuadorPichinchaMindo, 3.5 km NE ofKU 164207; Cadle & Savage 2012
EcuadorPichinchaPachijalUSNM 237057; Cadle & Savage 2012
EcuadorPichinchaRoad to MindoArteaga et al. 2013
EcuadorPichinchaSéptimo ParaísoArteaga et al. 2013
EcuadorPichinchaYellow House LodgeArteaga et al. 2013
EcuadorSanto Domingo de los TsáchilasAlluriquínQCAZ 8427; Arteaga et al. 2013
EcuadorSanto Domingo de los TsáchilasOtongachiArteaga et al. 2013
EcuadorSanto Domingo de los TsáchilasRío BabaAMNH 113019; Cadle & Savage 2012
EcuadorSanto Domingo de los TsáchilasSanto Domingo de los ColoradosMCZ R-166462; Cadle & Savage 2012
EcuadorSanto Domingo de los TsáchilasSanto Domingo de los Colorados, 5–10 km SSW ofAMNH R-113019; Cadle & Savage 2012