Puerto Rico is an island archipelago known for its high biological diversity. Its isolation from continental landmasses has led to a remarkable degree of endemism, meaning many species of plants and animals exist here and nowhere else on Earth. The island’s varied habitats, ranging from tropical rainforests like El Yunque to dry forests and coastal mangroves, support a rich tapestry of life. This ecological wealth has earned Puerto Rico a designation as a global biodiversity hotspot, a status that underscores both its biological richness and the high degree of threat facing its unique ecosystems. The fauna of Puerto Rico is characterized by a low number of native terrestrial mammals but high diversity among amphibians, reptiles, and birds.
The Iconic Amphibians and Reptiles
The Coquí frog, a small tree frog and cultural icon, has a name (Eleutherodactylus coqui) that is an onomatopoeia of the male’s distinct two-note call. Puerto Rico is home to more than a dozen different Coquí species, all of which are endemic. These frogs possess a unique life cycle known as direct development, where they skip the free-swimming tadpole stage entirely. The eggs hatch directly into miniature froglets, which allows them to reproduce on land without relying on standing water.
The reptilian fauna features Anole lizards, sometimes called the “chameleons of the Caribbean” due to their ability to change color. Over a dozen Anole species are found on the main island and its surrounding cays, each occupying a specific ecological niche. The common Puerto Rican Anole (Anolis cristatellus) is widespread, often seen performing display push-ups and extending its colorful dewlap to communicate territorial dominance.
The island also hosts larger reptiles, including the Puerto Rican Boa, which is the largest native snake species and is non-venomous. This reptile can reach lengths of six to eight feet and preys primarily on birds, bats, and small rodents. Another notable endemic reptile is the Mona Ground Iguana, a large terrestrial lizard found only on Mona Island off the west coast.
Avian Diversity: Endemic Birds and Migratory Visitors
Puerto Rico serves as a permanent or temporary home for approximately 349 bird species, with about 120 of those breeding on the island. The critically endangered Puerto Rican Parrot (Amazona vittata) is the only native parrot species in the archipelago. This vibrant green bird with a red forehead suffered population loss due to habitat loss. It is now the focus of conservation efforts, including captive breeding and reintroduction programs in the El Yunque National Forest and the Río Abajo State Forest.
Other endemic birds include the Puerto Rican Tody (Todus mexicanus), a tiny, bright green bird with a brilliant red throat. This species has an unusual nesting strategy, excavating a narrow, curved burrow up to a foot long in an earth bank to lay its eggs. The Puerto Rican Lizard Cuckoo (Coccyzus vieilloti) is known for its long, slender body and curved bill, which it uses to hunt lizards and large insects. Beyond the endemic residents, the island’s position in the Caribbean makes it an important stopover point for migratory species traveling between North and South America.
Marine and Coastal Life
The waters surrounding Puerto Rico are rich with marine species that rely on the island’s coastal habitats. The endangered West Indian Manatee (Trichechus manatus) feeds on the extensive seagrass beds found in shallow coastal areas. These gentle marine mammals face threats primarily from collisions with watercraft and habitat degradation in estuaries and bays like Jobos Bay.
Puerto Rico’s beaches are critical nesting grounds for four species of sea turtles:
- Leatherback
- Green
- Hawksbill
- Loggerhead sea turtles
The Leatherback sea turtle nests in areas like the northeastern coast between February and August. Juvenile Green and Hawksbill turtles feed in the vibrant coral reefs and mangrove habitats that fringe the island, which provide shelter and a diverse food supply. Seasonal visitors, such as humpback whales, are occasionally seen migrating through the deeper offshore waters during their winter breeding season.
Mammals: Mostly Bats and Introduced Species
Puerto Rico has a naturally low diversity of native terrestrial mammals. The only extant native terrestrial group is the bats, with 13 species recorded, including several endemics. These bats fulfill important ecological roles as insectivores, pollinators, and seed dispersers for native plants.
In contrast, the island has numerous introduced species, which have had a significant impact on the ecology. The small Asian mongoose was brought in during the late 19th century in an unsuccessful attempt to control rat populations in sugarcane fields. The mongoose is now a predator of native ground-nesting birds and reptiles, including sea turtle eggs and the Puerto Rican Tody’s nestlings. Feral cats, dogs, and rats also contribute to predation pressure on native wildlife.