At the southern gateway to the Caribbean, the sister islands of Trinidad and Tobago offer the perfect introduction to tropical birding. Tropical countries on the mainland can be overwhelming to birders who are new to these latitudes, but managing Trinidad’s 300+ regularly occurring bird species (with about 150 on the much smaller Tobago) is good for the ego. The endemics are straightforward: The critically engendered Trinidad Piping Guan is only found on the big island, and Trinidad Motmot occurs on both Trinidad and Tobago. Then consider that over half (about 180) of T&T’s regularly occurring birds have never occurred elsewhere in the Caribbean, giving the islands a decidedly “mainland” birding experience. Eight different pigeons represent T&T’s South American birds, along with Little Tinamou, Southern Pochard, and Common Potoo. Guided tours will take you to see the bizarre Oilbird. At least 15 unique hummingbirds stand out, including the handsome White-necked Jacobin and the rare White-tailed Sabrewing. Other South American specialties include the Southern Lapwing and the pretty little Pearl Kite. When it comes to Passerines, 10 families of T&Ts birds are absent from the Caribbean avifauna, including the Manakins, Antbirds, Woodcreepers, and Spinetails. And don’t miss the mainland tropical tanagers, which are well-represented here, including the Purple Honeycreeper and Bay-headed Tanager. Once you’ve IDed all the birds on the islands, take some time to see Tobago’s nesting Leatherback Turtles—the world’s largest living turtle. While you are there, look for the Crab-eating Raccoon. Back on Trinidad, sort through the 600+ butterflies recorded on the island. If you really want some local color, time your trip for Carnival—this is the birthplace of the celebration, and that of calypso music and limbo dancing. If you are traveling on your own, be prepared to drive on the left side of the road, and don’t be surprised to see 6-lane highways and a booming industrial infrastructure in the 3rd richest country (per capita GDP) in the Americas.
Trinidad and Tobago have a higher concentration of terrestrial mammals than do their other Caribbean counterparts. Red Howler monkey, Capuchin, Brazilian Porcupine, Spiny rat, Red-rumped Agouti, Ocelot, Raccoon and Collared Peccary and a large variance of Bat species, are just some of the encounters you may have while visiting. Outside of mammals one may observe Glass frog, Poison Arrow frog, Gecko, Iguana, Skink, Teiid, Sea turtle, Alligator and Caiman in their natural habitat.
Trinidad is the birthplace of Carnival, Calypso music, and limbo dancing, so make sure you get to experience some local color. Tobago has the best access to marine recreation, and as the southern gateway between the Atlantic and Caribbean, the snorkeling and diving can be outstanding.
Trinidad hosts far fewer North American migrants (especially songbirds) than other Caribbean islands, so it's less important to visit during the northern winter. You are going here for the Venezuelan and Caribbean specialties, so early breeding season may be one of the best times, such as March through June. Seabirds typically nest earlier than this, so the northern winter--after December--is the best time to see nesting tropicbirds. "Rainy" season is May-December, but remember that it can rain anytime in the tropical latitudes, especially as you get closer to the equator.
Asa Wright Nature Center is probably the best local clearinghouse for information.