Costa Rica is globally recognized as a center for remarkable biodiversity, drawing visitors seeking to observe its abundant wildlife. This small Central American nation hosts an extraordinary concentration of species, estimated to be around 5% of the world’s known species, despite covering only about 0.03% of the Earth’s land surface. This biological richness is largely due to its unique geographical position as a narrow isthmus connecting North and South America.
The country’s diverse topography includes high volcanic peaks, misty cloud forests, hot dry forests, and lush tropical rainforests. This variety of habitats, coupled with coastlines on both the Pacific Ocean and the Caribbean Sea, creates numerous specialized ecological niches that support a wide range of fauna.
Iconic Tree-Dwelling Mammals
The arboreal mammals of Costa Rica are among its most famous inhabitants, relying almost entirely on the rainforest canopy for survival. Sloths are iconic residents, represented by the brown-throated three-toed sloth and Hoffman’s two-toed sloth. The three-toed sloth has a specialized diet of leaves and an extremely slow metabolism, which conserves energy and sustains it on low-nutrition foliage.
Both sloth species are solitary and move at a sluggish pace, a defensive adaptation that makes them difficult for predators to spot. They descend to the ground only once a week to defecate. Symbiotic algae growing on their coarse fur aids their camouflage, giving them a greenish tint that helps them blend into the humid environment.
Monkeys are also prominent in the canopy, with four species regularly observed. The mantled howler monkey is notable for its loud, resonant calls, which can travel up to five miles through the dense rainforest, often heard at dawn and dusk. These vocalizations are used to mark territory and communicate with other groups.
The white-faced capuchin monkey is highly social, intelligent, and omnivorous, consuming fruits, insects, and small vertebrates. The Geoffroy’s spider monkey, found primarily in the Osa Peninsula, uses its prehensile tail as a fifth limb to swing gracefully through the trees. The small Central American squirrel monkey, or mono titi, is an endangered species often seen in the Pacific coastal forests, particularly within Manuel Antonio National Park.
The Extraordinary Avian Population
Costa Rica hosts over 900 avian species, including both resident and migratory birds adapted to specialized niches. The resplendent quetzal, a member of the trogon family, is one of the most sought-after sightings, primarily found in the high-altitude cloud forests of the Talamanca mountain range.
Male quetzals are recognizable by their iridescent green plumage, crimson breast, and elaborate tail feathers that can measure up to three feet long during the breeding season. Toucans are another visible group, with six species present, including the keel-billed toucan. This species is distinguished by its massive, brightly colored bill. Despite its size, the beak is surprisingly lightweight and is used for both feeding and regulating body temperature.
Macaws, the largest parrots, are represented by the scarlet macaw and the great green macaw. Conservation efforts have helped the scarlet macaw population recover, making them a common sight along the Pacific coast, particularly near Carara National Park. The great green macaw is rarer, found mainly in the Caribbean lowlands.
The country also boasts over 50 species of hummingbirds documented across different elevations. These iridescent birds, such as the miniature Scintillant Hummingbird, are the most species-rich avian family in the country. They are vital pollinators, feeding on nectar while hovering mid-air.
Diverse Reptiles and Amphibians
The warm, humid climate of Costa Rica supports over 220 species of reptiles and about 160 species of amphibians. The rainforest floor and foliage host numerous frog species, including the famous non-venomous red-eyed tree frog, known for its vibrant green body, blue-striped sides, and bright red eyes. Delicate glass frogs are also found here, characterized by translucent skin that allows their internal organs to be seen.
Poison dart frogs, such as the green-and-black species, use striking aposematic coloration as a warning sign to predators about the potent toxins secreted through their skin. While most Costa Rican snakes are non-venomous, the country is home to dangerous species, including the fer-de-lance, a pit viper responsible for a majority of snakebite incidents. Common, less threatening reptiles include the green iguana and the basilisk lizard, nicknamed the “Jesus Christ lizard” for its ability to run across water.
Near rivers and coastal estuaries, two large crocodilians reside: the American crocodile and the spectacled caiman. The American crocodile is the larger of the two, sometimes reaching up to six meters in length, and is often seen basking along the banks of the Tárcoles River. The smaller spectacled caiman has a broader snout and is generally more timid.
Coastal and Open Ocean Fauna
The Pacific and Caribbean coastlines support a distinct array of marine life separate from terrestrial rainforest species. Sea turtles are a major highlight, with several species using the beaches as nesting grounds:
- The Olive Ridley sea turtle nests in large groups, known as arribadas, at Ostional National Wildlife Refuge on the Pacific coast (June to December).
- The green sea turtle primarily nests on the Caribbean coast at Tortuguero National Park (July to October).
- The massive leatherback sea turtle, the largest turtle species, nests on both coasts (Caribbean: February to June; Pacific: October to February).
The open ocean waters are home to migratory marine mammals, most notably humpback whales. These majestic cetaceans migrate from both the northern and southern hemispheres to breed and give birth in the warm tropical waters off the Pacific coast. This double migration means that humpbacks can be observed almost year-round, with peak seasons occurring from July to October and again from December to April. Playful dolphins, including bottlenose, spinner, and spotted dolphins, are year-round residents often seen traveling in pods close to the coastline.