Mexican Tree Frog (Smilisca baudinii)

The Mexican Tree Frog is among Costa Rica’s biggest frogs. It is somewhat similar in appearance to the Masked Tree Frog, however the Mexican is bigger; its overall color is brown instead of green, and does not show such a definite dark brown patch behind the eye. The eyes are very similar between both species. It does occur in the Guanacaste province, from which the Masked is absent, however it is not found on the Pacific south from the Tarcoles river. They are nocturnal and arboreal like most tree frogs.

Dusty Glass Frog (Teratohyla pulverata)

Glass Frogs are fascinating, given their transparent ventral skin, which lets us peak into the internal structure of a frog. The organs that are visible varies according to the species, with some species showing the intestines and lower organs, while others show the heart and upper structure. In some of them, the bones are also visible inside the legs. Most of these frogs are overall green in coloration, which provides camouflage in the forest environment they live in.

This species is called Dusty given how the dorsal skin is covered in very small white spots. They are intermediate between the sizes of Strawberry and Green and Black Poison Dart Frogs, and definitely bigger than the Dwarf Glass Frog, which belongs to the same family of frogs. Their skin is mostly green, with yellowish tints in the ventral surfaces of the limbs and in the tips of fingers and toes. Given these colors, it is not surprising that one could be staring directly into one of these on a leaf and still not find it. The eyes are very large, located at each side of the head, enabling the frog to spot predators from both sides; the pupil is horizontally eliptical, while the iris is covered with an intricate pattern of blue and gray.

Boulenger’s Long-snouted Tree Frog (Scinax boulengeri)

There are three Long-snouted Tree Frog species in Costa Rica, with the Boulenger’s and Olive being both widespread and common accross wet lowlands in the country, and the Dry Forest species being common in the northwestern region (Guanacaste). The Boulenger’s is mostly light brown, including the iris, with small patches of green and darker brown that provides better camouflage. It is colloquially known as “Rana Lagarto” (crocodile frog) in Costa Rica due to its unusually long snout.

It is arboreal and nocturnal, and males frequently call with their body upside-down during the wet season. To help hold this position, the innermost finger can be rotated up to 90 degrees, essentially pointing upwards, which provides a better grip on smooth surfaces like tree branches and trunks. The skin is granular, which might put off some people that feel that its appearance is gross. Yet amphibians have a very important role in wet ecosystems, as some of the insect prey they consume might develop into plagues if unchecked. Most amphibian species have been battling with declining populations, and protecting them from extinction is one of our biggest challenges.

Red-eyed Tree Frog (Agalychnis callidryas)

The Red-eyed Tree Frog is easily one of the best recognized frogs in Costa Rica. It is featured in most ads promoting eco-tourism activities to both nationals and foreigners. Its colors are very bright and varied, ranging from the white belly and throat, green dorsum and sides of the arms and legs, blue on the inside part of the arms and legs, orange hands and feet, and the reddish eyes with conspicuously vertical black pupils; such a cocktail of colors is sure to attract predators.

With so much separation between both eyes, these frogs can almost look in two opposite directions at the same time, an incredible adaptation that enables them to spot potential predators and prey. They also have what’s called a nictitating membrane, which is transparent skin below the lid that helps protect the eye and keep moisture when the eye lid is open. The iris is all covered in veins and the eye is large in comparison with the body, helping this species see very well in the dark forest

Rain can be easily simulated during a night photoshoot using a spray bottle, as the flash will illuminate the drops as they fall and freeze the action. If one would want longer looking drops, then the use of a continuous source of light can help. This makes for more natural looking images, as most tree frogs are nocturnal in nature and become more active during or after rainy evenings. It is common to hear them calling from ponds and branches, most normally males trying to attract females to mate.

Masked Tree Frog (Smilisca phaeota)

The Masked Tree Frog is a nocturnal, arboreal species that can be found on the lowlands and foothills of both the pacific and caribbean sides of Costa Rica, although it does not occur on the dry plains of Guanacaste. Its color is variable, however the dark brown patch behind the eye is unmistakable.  Their color ranges from entirely tan to entirely green, with intermediate, contrasty patterns in between. When most of their body is tan, it can look very similar to the Cross-banded Tree Frog, however the Cross-banded never has a mask. Their vocal sacs are bilobed, which essentially means that it looks like two vocal sacs, one at each side of the throat.

I have an story of a time I visited Mirador El Pizote, in Boca Tapada, San Carlos. One of these frogs had entered the cabin where I stayed, possibly during the night. I was going for a bath and found the frog resting on the bathroom. After trying a few pictures (that did not work out very well), I tried to grab it to put it outside, but it jumped rapidly and dissappeared. Since I could not follow its movement, I was never sure whether it went outside or stayed inside.

Chiriqui Robber Frog (Pristimantis cruendus)

The Chiriqui Robber Frog is a rare nocturnal, arboreal inhabitant of humid lowland and montane forests in tropical countries, namely Costa Rica, Panama and Colombia. Their color and pattern is highly variable and cryptic, but overall includes varying shades and patterns of dark colors like brown and black, which helps them to camouflage easily in the forest. It lacks webbing on the hands and feet, but shows greatly enlarged disks on the toes and fingers. The best field mark to identify this species is the black reticulum on the brown eye.