Trinidad and Tobago are continental islands with a geologically very recent history of direct land bridge connection to South America. As a result, unlike most of the Caribbean Islands, Trinidad and Tobago supports a primarily South American flora and fauna and has greater diversity of plant and animal species than the Antilles. However, rates of endemism are lower than in the rest of the Caribbean because there has been less time for genetic isolation from mainland populations. Specifically, a land bridge to Venezuela existed fairly recently in Trinidad, allowing fewer opportunities for speciation than in Tobago, as well as a lot of overlap in biodiversity with the South American mainland.
Trinidad is nearer to mainland South America and has been directly connected to the mainland via land bridges more often and for longer periods than Tobago. This, as well as Trinidad's larger size and more varied topography and hydrology compared to that of Tobago, allows more ecosystem diversity in the former island compared to the latter.
Plant communities
The standard description of plant communities follows John Beard's work (Beard, 1946). He classified natural vegetation in a hierarchical fashion on the basis of the physiognomy of the dominant trees.
Seasonal formations Evergreen seasonal forest Semi-deciduous seasonal forest Deciduous seasonal forest Dry evergreen formations Littoral woodland Montane formations Lower montane forest Montane forest Elfin woodland Edaphic formations Mangrove forest Palm swamp Seasonal swamp forest Seasonal swamp savanna Herbaceous swamp
Terrestrial animal communities
Mammals
Trinidad and Tobago is home to about 99 species of terrestrial mammals. About 65 of the mammalian species in the islands are bats (including cave roosting, tree and cavity roosting bats and even foliage-tent-making bats; all with widely differing diets from nectar and fruit, to insects, small vertebrates such as fish, frogs, small birds and rodents and even those that consume vertebrate blood). The next most diverse group of mammals in the islands are the rodents. The largest of these rodents are the lowland paca, the long-tailed porcupine, and the red-rumped agouti (of these, only the agouti remains extant on Tobago). One squirrel (the red-tailed squirrel) and several native rats and mice are also part of the rodent fauna. A few species of opossums including the common opossum may be found on both islands.
Two anteaters, the southern tamandua and the silky anteater are found in Trinidad (but not in Tobago). The nine-banded armadillo can still be found on both islands. Native mammals of the order Carnivora include the ocelot, the tayra, the Neotropical river otter and the crab-eating raccoon (all four being found on Trinidad, with only the raccoon still extant on Tobago). The small Indian mongoose was introduced to Trinidad (but not to Tobago) during the later part of the 19th century and is now naturalized. The two native hoofed-mammals still found in Trinidad include the red brocket deer and the collared peccary (in Tobago, the deer is thought to be extirpated and the peccary is now fairly rare). The Guyanan red howler monkey and the Trinidad white-fronted capuchin are Trinidad's two native non-human primate species. The tufted capuchin monkey was introduced to the northwestern peninsula of Trinidad during World War II and is now naturalized there. No monkeys remain extant on Tobago. For comments on native aquatic mammals (namely manatees) and native marine mammals (whales and dolphins), see the appropriate sections below.
Birds
472 species of birds have been recorded in Trinidad and Tobago (and the list of recorded species seems be still slowly increasing from year to year). There are few places in the world where so many birds can be seen in such a small area (with probably one of the highest bird species to area ratios of any country). Many of the species are very rare or are of particular interest. They range from the many species of hummingbirds to the primitive cave-dwelling oilbird (that uses sonar to fly in the dark) to the spectacularly beautiful scarlet ibis. The islands are within a few miles of Venezuela, and the species are therefore typical of tropical South America. However, the variety (although quite exceptional for such a small geographic area) is somewhat impoverished compared to the mainland, as would be expected with small islands.
The resident breeding birds are augmented in the northern winter by migrants from North America.
Tobago has only about half the number of bird species of Trinidad, but about 22 birds have been reported only from Tobago, including 12 breeding species.
The country hosts a few endemic avian subspecies and two endemic species (the critically endangered Trinidad piping guan found only in Trinidad, and the Trinidad motmot found on both islands, but more common in Tobago).
Amphibians and reptiles
The best sources of information regarding the recorded amphibians and reptiles of Trinidad and Tobago to date are Murphy (1997) and Boos (2001). Since those publications, a few new records as well as several taxonomic changes have been made (Murphy and Downie, 2012). The herpetofaunal list is at present in a state of flux, as taxonomy and systematics continue to be revised. To date (July 2014), the generally accepted recorded numbers of species of the various major groups of amphibians and reptiles are as follows:
Frogs and toads (Anura): 37 species in total for the country. (33 recorded from Trinidad and 15 recorded on Tobago, with 4 of those from Tobago not known from Trinidad, and 2 of those from Trinidad known from just one specimen each. There is one introduced species, known on both Trinidad and Tobago).
Caecilians (Gymnophiona): 1 species in total from Trinidad only. (Recorded from only 1 specimen).
Turtles, terrapins and tortoises (Chelonii): 14 species recorded in total for the country (All 14 recorded for Trinidad, and possibly 6 recorded for Tobago. Four species are marine, with at least 4 being noted off Tobago, with at least 3 of those regularly breeding on both islands. Four are confirmed native terrestrial system species of Trinidad (1 of these is possibly a waif on Tobago). One is possibly a long introduced species on both islands that is still present in the wild in some areas of Trinidad, but unconfirmed in the wild in Tobago. One is very recently introduced in Trinidad from North America and it is unconfirmed if it is breeding in the wild. Three are possibly occasional waifs to Trinidad from the nearby continent with no verified local breeding populations).
Crocodiles and alligators (Crocodylia): 4 species recorded in total for the country (two are known to be native and breeding on Trinidad, with one of those breeding in Tobago, while the other 2 were occasionally historically recorded as waifs).
Legless lizards (Amphisbaenia): 2 species from Trinidad only.
Lizards (Sauria): 31 confirmed records for the country in total (2 of those not yet 'officially' documented). (Of the 31 confirmed records, 27 are from Trinidad, with at least 7 relatively recent historical introductions with 1 of these subsequently assumed to have been extirpated. Nineteen are from Tobago, with at least 3 relatively recent historical introductions there. Four of those from Tobago are not found on Trinidad. In addition to the 31 confirmed records, there are at least 3 species records that are dubious).
Snakes (Serpentes): 50 accepted records for the country in total (1 of these not yet 'officially' documented). (Of these 50 records, 45 are from Trinidad and 22 are from Tobago, with 5 of those from Tobago not being recorded from Trinidad. Of the 50 records for the country, 7 species are known from just 1 or 2 records. In addition to the 50 generally accepted confirmed records, there are at least 2 dubious records).
A number of frogs and toads inhabit the islands, including the well known huge marine or cane toad (Rhinella marina), locally known as the crapaud on both islands, and the tiny colourful rare endemic species known as the El Tucuche golden tree frog (Phytotriades auratus), found only in the giant epiphitic bromeliads at the mist-shrouded summits of Trinidad's two highest peaks, as well as the Mount Tucuche tree frog (Flectonotus fitzgeraldi), found in the Northern and Central Ranges of Trinidad and throughout most of Tobago. In the same genus as the marine toad, the Rivero's toad (Rhinella beebei) is found in the cane fields, rice fields and other open agricultural areas of Trinidad (absent in Tobago). The strangest of all Trinidad's frogs is the highly aquatic Suriname toad or pipa toad (Pipa pipa), the tadpoles of which develop in the skin tissue of the mother's back, before bursting out and emerging as miniature replicas of the adult frogs. Another unusual frog found in Trinidad is the paradoxical frog (Pseudis paradoxa) in which the tadpoles of the species are approximately 25 cm long and the adults shrink to about 6.5 - 7.5 cm; this reduction of size from the tadpole to the sexually mature adult is how the species received its common name. The Amazon River frog (Lithobates palmipes) is found near ponds, slow flowing rivers and other permanent water sources, usually in tropical forests, in the Central Range of Trinidad (not located in Tobago). The giant tree frog (Boana boans), known locally as the giant flying frog, is commonly heard calling after dusk from the vegetation along forest-lined streams in Trinidad. Other frogs of the same genus include the banana tree dwelling frog (Boana platanera) (found on both islands), as well as the map tree frog (B. geographica) and the polka-dot tree frog (B. punctata) which are native to Trinidad, not Tobago.
Other frogs in the family Hylidae include species in the genus Dendropsophus (D. microcephalus, D. minusculus and D. minutus), the veined tree frog (Trachycephalus typhonius), the red snouted tree frog (Scinax ruber), the Orinoco lime tree frog (Sphaenorhynchus lacteus) and the Maracaibo Basin tree frog (Scarthyla vigilans). In the family Microhylidae, there are only two species found in Trinidad (not Tobago), both in the genus Elachistocleis: E. nigrogularis and E. surinamensis. The Trinidad leaf frog (Phyllomedusa trinitatis) can be found in the lowland forests, the edges of forest and montane rainforests in the northern region of Trinidad (not Tobago). The two frog species of the genus Mannophryne found diurnally active in forests along fast flowing mountain streams (one of which is endemic to Trinidad (M. trinitatis) and the other endemic to Tobago (M. olmonae)) both demonstrate a degree of parental care as the tadpoles are transported on the backs of the adult males before a suitable fairly predator-free body of water is found where they may be left to develop. Other frogs native to Tobago are the eastern glass frog (Hyalinobatrachium orientale) which can be found on leaves near streams, creeks or rivers and the Tobago litter frog (Pristimantis charlottevillensis) which is endemic to the island and is found near forest and grassland streams. The relatively recently introduced Grenadian 'tink' frog (Eleutherodactylus johnstonei) can be heard at night in loud metallic 'tinking' choruses in urban residential neighbourhood yards and parks from Diego Martin to Sangre Grande in Trinidad, and more recently in southwestern Tobago. The tungara frog or locally called the pung-la-la (Engystomops pustulosus) is commonly heard at night calling from wet grassy ditches in open habitats in both urban and rural areas on both islands and their foam nests are found even in small road and trail side puddles during the rainy season. Other frogs in the same family include Turpin's litter frog (Pristimantis turpinorum),