El Yunque National Forest, located in the Sierra de Luquillo mountains, represents the primary rainforest environment in Puerto Rico. This unique area is designated as the only tropical rainforest within the United States National Forest System, spanning over 28,000 acres of lush, biodiverse terrain. The island’s isolated geography promotes a high degree of endemism, meaning many animal species found here exist nowhere else on Earth. This concentration of unique life forms makes the Puerto Rican rainforest a globally significant ecological treasure.
Amphibians and Reptiles
The Coquí frog is the most recognized voice and unofficial symbol of the Puerto Rican rainforest, defining the nightly soundscape. This common name refers to over a dozen species of small, arboreal frogs within the genus Eleutherodactylus, with 13 species residing in El Yunque alone. The scientific name translates to “free toes,” a reference to a defining feature: the Coquí lacks the webbed feet typical of most frogs. Instead, it uses specialized toe pads, or sticky disks, which allow it to cling effortlessly to the vertical surfaces of leaves and trees, facilitating its life high in the forest canopy.
The frog’s name is an onomatopoeia derived from the male’s distinctive, two-note call, which is heard from dusk until dawn. The initial “co” sound functions primarily to repel rival males and establish territorial boundaries. The second, higher-pitched “quí” note is specifically meant to attract females to the male’s location.
Lizards, particularly the Anole species, are also highly visible inhabitants of the warm, moist forest understory. There are approximately 11 species of Anolis lizards in Puerto Rico, frequently seen darting across palm trunks and bamboo stems. The Emerald Anole, for instance, is a small, bright green reptile known for its ability to change color to a darker brown when excited or threatened.
Among the larger reptiles is the Puerto Rican Boa (Epicrates inornatus), the island’s largest native snake, which can grow to an average length of six to seven feet. Known locally as “culebrón,” this non-venomous constrictor is a solitary, nocturnal hunter that preys on lizards, birds, and bats. Though rarely seen by visitors, it plays an important role in the food web and is one of the species under active conservation efforts in the forest.
Endemic Birds and Resident Flyers
Avian life in the Puerto Rican rainforest includes several unique species, demonstrating the high level of endemism found in the Caribbean archipelago. The most significant of these is the endangered Puerto Rican Parrot (Amazona vittata), a predominantly green bird distinguished by a bright red forehead and white eye-ring. This parrot is the only native parrot species remaining in the archipelago, and its survival depends on the conservation of mature forests that contain deep tree cavities suitable for nesting.
Conservation efforts for the parrot began in the late 1960s when the wild population plummeted to fewer than two dozen individuals. Though the population remains low and is vulnerable to natural disasters, dedicated breeding and release programs have established a small but persistent wild population within El Yunque.
Another endemic bird is the Puerto Rican Tody (Todus mexicanus), measuring only about four inches long. The Tody is easily identified by its vibrant emerald-green back, white belly, and a striking red throat patch. This insectivore forages by perching quietly and then making short, rapid flights to snatch insects directly from leaves or in mid-air. The Tody, along with other residents like the Puerto Rican Lizard-Cuckoo and various hummingbirds, contributes to the forest’s acoustic and visual diversity.
Terrestrial Mammals and Insect Diversity
The native terrestrial mammal population of the Puerto Rican rainforest is notably limited, a common characteristic of isolated island ecosystems. The only extant native terrestrial mammals are 13 species of bats, which arrived by flight and have since diversified across the island. Bats are ecologically diverse, with species performing roles as insectivores, frugivores, and nectarivores.
For example, the Red Fig-eating Bat (Stenoderma rufum) is a native frugivore, while the Greater Bulldog Bat (Noctilio leporinus) is one of the few species globally that primarily fishes for its food. These nocturnal flyers are essential for seed dispersal and the pollination of many forest plants. Other non-native land mammals, such as the Small Indian Mongoose, were introduced by humans and can pose a threat to the native fauna.
The vast majority of animal life in El Yunque belongs to the invertebrate category, which is ecologically dominant. Insects and other arthropods are crucial components of the ecosystem, driving decomposition, nutrient cycling, and serving as the base of the food web.
Research has documented over 1,200 insect species in just one study area of the forest. Visitors may encounter large, non-venomous invertebrates like the Puerto Rican tarantula, various species of colorful butterflies, and impressive, camouflaged walking sticks. The forest floor is also home to abundant tree snails, which contribute to the health of the soil and undergrowth.