Biodiversity is both the foundation that supports all life on land and in the water and its self composed of life forms. It affects every aspect of human health, providing clean air and water, nutritious foods, scientific understanding and sources of medicine, natural disease resistance, and climate change mitigation. Changing, or removing one element of this web affects the entire life system and can produce negative consequences. Human actions, including deforestation, encroachment on wildlife habitats, intensified agriculture, and acceleration of climate change, have pushed nature beyond its limit. It would take 1.6 Earths to meet the demands that humans make of nature each year. If we continue on this path, biodiversity loss will have severe implications for humanity, including the collapse of food and health systems. The emergence of COVID-19 has underscored the fact that, when we destroy biodiversity, we destroy the system that supports human life. Today, it is estimated that, globally, about one billion cases of illness and millions of deaths occur every year from diseases caused by coronaviruses; and about 75 per cent of all emerging infectious diseases in humans are zoonotic, meaning that they are transmitted to people by animals. Nature is sending us a message.
Welcome to World Environmental Day. Here we are going to look at the snakes found on the island of Tobago. Snakes are important parts of the environment. They are all predators and at the same time provide food for other predators and scavengers. They help control the populations of their prey and perhaps more important they are beautiful animals that everyone can appreciate. The island of Tobago has 22 species of snakes, but there are about 3800 species of snakes known from around the world. Scientists are still discovering new species and some of those have been found on Tobago quite recently.
Snakes inspire fascination and feelings in a way that no other animal can. These legless reptiles play important roles in the natural environment and food webs. Effective hunters and ambush predators, snakes use their highly-developed senses of sight, taste, hearing and touch to locate, recognize and track their prey. Some snakes use venom to paralyze and kill their prey while others use their powerful muscular bodies to constrict their prey. Some snakes burrow in the soil; squeeze through cracks and crevasses in rocks; climb near vertical rock walls and span the thinnest branches of bushes and trees; and some are excellent swimmers. They come in a kaleidoscope of colors and patterns, mostly mirroring their surroundings, with a few brightly banded and flecked, or giving off a brilliant sheen in sunlight. Snakes inhabit a full range of environments from the rainforest to the backyard garden. The more you learn about snakes the more you learn they are incredible creatures worthy of our respect and protection – and animals that we can learn to live with.
Macajuel or Boa Constrictor (above and below)
Size. About 4 m total length, females are larger than males, new born snakes are 320−450 mm; tail about 8% of the body length.
Identification. smooth dorsal scales in 81−95 rows at mid-body; anal plate single. Labials lack the heat sensing pits. Dorsum tan or gray with dark red-brown transverse marking. Colours change posteriorly, tan areas become cream, or almost white, and brown transverse blotches become red. A brown stripe from snout passes through the eye and extends to first transverse band. Males have a lighter body build and larger preanal spurs than females.
The Boa Constrictor may be the world’s best known snake, at least in terms of name recognition, but it may be confused with other boid snakes. The boa’s crown does not have any plate-like scales, and the nasal scales are separated by at least 4−5 tiny internasals, a characteristic that separates it from all other Trinidad and Tobago snakes. The anaconda is a heavier bodied, dark olive-green snake with a row of dorsolateral blotches or rings. The scales between the eyes of the Boa constrictor are small, about the same size as those on the back of the head, and number about 25−30; in the anaconda the scales between the eyes are large and number only four or five. Ruschenberger’s Treeboa is usually a uniform khaki-brown to yellow-brown snake with a very slender forebody and wide head, and it has labial pits; Boa Constrictors lack labial pits. The rainbow boa is purple-brown with a series of darker rings on its upper body; it has 4−6 scales between the eyes, and it has shallow labial pits which are used in sensing heat.
Traffic is a major hazard for snakes on Tobago. If you see a snake on the road, slow do, go around it. Don’t drive over it. This Macajuel was fortunate in that some Tobago residents had stopped to look at it and prevented others from injuring it.
Ruschenberger’s Treeboa (Cascabel), Corallus ruschenbergerii (above)
On the Main Ridge, but found island wide, usually in forests along streams. It comes in two color variations, a dark colored morph (left) from the forests of the Main Ridge and a light yellow morph from the lower elevations on the island (below).
Rainbow Boa or Velvet Mapepire, Epicrates maurus (below)
It is common in agricultural areas where it feeds on rats and mice and occasionally birds. Juveniles boldly marked mid-dorsum with 35–40 bronze-gold spots outlined in black; head with black midline stripe and two black stripes above and behind each eye; sides with three or four rows of black spots; venter uniform off-white.
Similar species. May be most likely mistaken for its close relative, the anaconda, which completely lacks labial pits and is not found on Tobago; E. maurus has shallow labial pits. It can be distinguished from all other boids because it lacks subocular scales and several of the upper labials enter the orbit. The high number of scales around the body (53-63) also distinguish it from all of the other advanced snakes (colubrids and dipsadids) on the islands.
The Cribo, Drymarchon corias, (above)
This is a large snake that lives on the ground but will climb. It eats most animals it can over power. This is one of Tobago’s rarest snakes. The photo was taken in 1979, we are not sure if its has been seen since. Perhaps most easily confused with the Tiger Rat Snake which has an even number of scale rows at mid-body (18 or less) and is jet black with yellow markings. The Yellow-puffing Snake is also a large colubrid that has a yellow and black dorsal pattern, but it has 21 scale rows at mid-body and a tail that has more than 120 subcaudals. We thanks Alvin Braswell for the use of the photograph.
Parrot Snake, Leptophis coeruleodorsus, (below)
A thin, bright green snake with a copper-coloured lateral stripe; belly uniform cream. Vertebral scales slightly larger than lateral scales; dark stripe passes through the eye. Eyes are large; dorsal scales 15−15−13, rows above two usually keeled. These snakes are excellent climbers but they will also hunt for lizards on the ground.
Hailey’s Parrot Snake, Leptophis haileyi (below)
This snake was described in 2013 and it has not been found since the first specimen was collected. It is larger than the Parrot Snake, and it is known only from Tobago’s Main Ridge.
To the right the photo compares the common Parrot Snake (A) to Leptophis haileyi (B).
The Tobago Racer, Mastigodryas dunni (above)
This snake is found in disturbed areas and forest edges and occurs over most of the island. While it is closely related to the Tropical Racer, Mastigodryas boddaerti found in Trinidad and mainland South America, herpetologists are uncertain of its species or subspecies status status. In either case it appears endemic to Tobago.
Size. 776 mm SVL, 881 mm TL, hatchlings 240 mm; tail 35% SVL. Identification. Dorsal scale rows 17 at mid-body, reduced to 15 posteriorly; each scale has a pair of apical pits, otherwise smooth. We thank Stephen L. S. Smith for the photos.
Brown Vine Snake, Oxybelis rutherfordi (below)
Found island wide. While this snake is currently considered to be a widespread species ranging from Arizona to Argentina, I have understand that the Trinidad and Tobago populations will soon get a new name. This snake specializes in eating lizards and while it usually hunts in bushes and trees, it will also hunt on the ground. Defense behavior includes: threaten with an open mouth and expose a black or dark violet mouth lining. It may also release the contents of its cloacal glands when handled. Vine snakes have a low body mass to length ratio. This allows them to span gaps with their body and reach prey on branches that many other snakes cannot.
Tropical Rat Snake, Spilotes pullatus. (above)
The species is in the forests on the Main Ridge in the Forest Reserve but also in low forests right down to sea level. Tobago specimens tend to be melanistic – that is they have less white and yellow pigments and more black pigment. This large snake feeds primarily on birds and mammals. Diurnal, but frequently seen sleeping on trail side vegetation at night. The diet is mostly lizards, but frogs and small birds are also eaten. Reproduction: Clutches of 3–6 eggs are laid in May-June. Defense: When disturbed it will threaten with an open mouth and expose a black or dark violet mouth lining. It may also release the contents of its cloacal glands when handled. Vine snakes have a low body mass to length ratio. This allows them to span gaps with their body and reach prey on branches that many other snakes cannot.
Black-headed Snake, Tantilla melanochephala (below)
Probably found island wide. These are miniaturized snakes that feed on invertebrates, including centipedes and scorpions. Diurnal, but frequently seen sleeping on trailside vegetation at night. Diet is mostly lizards, but frogs and small birds are also eaten. Reproduction: Clutches of 3–6 eggs are laid in May-June. They live in forest leaf litter.
Three-lined Ground Snake, Atractus trilineatus (above)
Probably found island wide. A small, leaf-litter dwelling snake that feeds on worms. A small, red-brown (female) to grey brown (male) snake with a sharply pointed head and longitudinal stripes. Snout and tail sharply pointed, dorsum brown-gray with three or four light lines; scales smooth in 15 rows at mid-body.
One-lined Ground Snake, Atractus fulginosus (below)
Found in the Main Ridge Forest Reserve, and surrounding area but may also be in Venezuela but not on Trinidad. This snake was known from only three specimens on Tobago, until Jan Weems found a clutch of eggs in an ant nest. The eggs were hatched and added five more known specimens from Tobago. It is unclear to us if this snake is the same species as the one in Venezuela, but we are working on it.
Trinidad Black-Backed Snake, Erythrolamprus melanotus nesos (above)
The only snake in Trinidad and Tobago with a broad black dorsal
stripe five scales wide bordered with yellow or salmon on the sides. Endemic to Trinidad and Tobago. It uses forest edge and open habitats, often near streams or bodies of water. It feeds on frogs and lizards.
Tobago Steam Snake, Erythrolamprus pseudoregina (below)
This recently described species (2019) is known only from northeastern Tobago, and likely to be endemic. However, its eventual discovery in Venezuela cannot be ruled out. It is currently known from five specimens. Habitat. Primary and old growth secondary forest. One specimen was found on a steep slope above a stream. It is diurnal.
Red Snake (Doctor Snake), Erythrolamprus ocellatus (above)
The Red Snake is found only in Tobago, including the Main Ridge Forest Reserve. It is a coral snake mimic without a mimic (there are no coral snakes on Tobago). Thanks to Stephen L. S. Smith for the photograph.
Blunt-headed Treesnake, Imantodes cenchoa (below)
A widespread species that specializes in living in bushes and tress and feeding on frogs and lizards. It is found on the Main Ridge and lowland forests.
Cat-eyed Snake, Leptodeira annulata (above)
A widespread on the island and on mainland South America. Often along stream edges. Also called Mapepire, Mapepire Valsyn, Annulated Night Snake, Banded Night Snake, False Mapepire, Cat Eyed Night Snake, Garden Snake, Night Snake. The Cat Snake can exceed a meter in length, but rarely does so i n Tobago, most specimens are less than 500 mm in total length. The only Trinidad and Tobago snake with 19 or 21 rows of smooth scales that are reduced to 15 rows near the vent, the vertebral row slightly enlarged; a vertical pupil. This snake specializes in feeding on frogs and their eggs.
Coffee Snake, Ninia atrata (below)
A common snake in leaf litter on plantations and in forests. This small snake can have a brightly colored collar , or not. The Coffee Snake is so named because it is common in coffee plantation throughout northern South America. Usually abouy 380 mm in total length. The only Trinidad and Tobago snake with a collar and uniform blue-black colour pattern on the dorsum; the venter is immaculate. The collar may be orange, white, or pink, and it may be absent in some specimens, particularly old adults. Scales are keeled and in 19 rows. Rostral visible from above; nasal single; loreal and preocular fused with loreal scale. It is nocturnal and has a diet that includes slugs (gastropods).
Ratonel, Pseudoboa neuwiedii (above)
A common snake at lower elevations on the island, including the lower Main Ridge. Juvenile Ratonels are bright red with a collar, adults turn a salmon-pink and have a darker head. These snakes eat a variety of lizards and rodents. They also have a potent venom and fangs located in the back of their mouth. They should not be handled. To our knowledge no humans have suffered envenom from this snake.
Slug-eating Snake, Sibon nebulatus (below)
It is also called the mapepire corde violin, fiddle string mapepire, cloud snake, cloudy snake. It is about 0.4 meters in length. Smooth dorsal scales in 15 rows, the vertebral row is slightly enlarged
It is a widespread species, ranging from Veracruz and Nayarit, Mexico, to Brazil and Ecuador. It lives in forests and forest edge; may be found on the ground, but it also climbs in vegetation; frequently found along streams. Where it finds snails and slugs for food.
Klauber’s Thread Snake, Epictia tenella (above)
It is a small, silvery, striped snake with a yellow face and yellow tail; each scale row has a dark stripe. Head no wider than neck. This threadsnake is known from Trinidad and we think it is present on Tobago base on some old literature. Threadsnakes spend most of their time in termite and ant nests where they feed on the eggs and larvae of the insects. They will climb trees to reach termite nests.
Lineated Blind Snake, Amerotyphlops trinitatus (below)
It lives in forests and at forest-edge and is likely be found in rotting logs, leaf litter, and loose soil. This species has been listed as critically endangered because many of its known locations are under or near development projects. However, it has been recently found in the Main Ridge Forest Reserve on Tobago. It is associated with Three-lined Snake and Hex-scaled Bachia (a small lizard) in ant and termites nest. It can be active any time of day. The diet includes ants and termites.