Fauna of Costa Rica - Amphibians

Amphibians

Costa Rica is home to around 175 amphibians, 85% of which are frogs. Frogs in Costa Rica have interesting ways of finding fishless water to raise their young in. Fish, of course, will eat tadpoles and eggs. Poison Dart Frogs put their eggs in water pools in bromeliads. Other methods include searching ponds before laying eggs, and laying eggs in wet soil. There are 35 species of Elutherodoctylus frogs, 26 species of Hyla frogs and 13 species of glassfrogs.

Notable frog species in Costa Rica include Red-eyed Tree Frog, a few species of Poison Dart Frogs, the semitransparent glassfrogs, and the large Smoky Jungle Frog. Some other notable toad species in Costa Rica include the ten species of Bufo toads and the Giant toad, a huge toad known for its wide appetite. It has been documented eating almost anything, including vegetables, ants, spiders, any toad smaller than itself, mice, and other small mammals.

Besides the frog species, approximately 40 species of lungless salamander and two species of caecilian are found in the country, both rarely seen and little known. Costa Rican amphibians range in size from the Rainforest Rocket Frog, at 1.5 cm (0.5 in), to the Giant toad, at up to 15 cm (6 in) and 2 kg (4.4 lb).

Representatives of all three orders of amphibians - caecilians, salamanders, and frogs and toads - reside in Costa Rica. Due to environmental degradation and the sensitive nature of amphibians to pollution, Costa Rica has seen declines and even extinctions in amphibian populations. Monteverde Cloud Forest Reserve is a critical habitat for certain species of the order Anura. However, forty percent of the members of this order that reside in this reserve are estimated to have gone extinct since 1987. This equals twenty species of frogs and toads.

The highland-dwelling Golden Toad, Bufo periglenes, has not been witnessed in its highly restricted habitat of the central mountain ranges of Costa Rica since 1989. Within one year, the number of juveniles counted at their most prevalent breeding site declined from over 1,500 individuals to only one. The International Union for the Conservation of Nature (IUCN) declared the Golden Toad endangered, but it is likely extinct due to the lack of sightings since over two decades ago. Suspected causes for the toads probable extinction include a combination of intense El Nino weather patterns which resulted in a drought, increased pollution added to the environment, climate change, and an invasive fungal species, Chiriqui Harlequin.

Amphibians in Costa Rica have acquired many adaptations for survival. Some frog species, especially those of the Poison Dart Frogs, have learned to lay eggs in water devoid of predatory fish. For some species this means laying eggs in small collections of water in the leaf litter, then transporting the eggs to bromeliads. Other species have adapted the ability of direct development. This means that the frog develops completely inside the egg without transitioning to the tadpole phase. This decreases vulnerable exposure to predators and the frog emerges from its egg as a froglet, much better equipped to protect itself.