White-lipped Rain Frog (Craugastor talamancae)

We found the White-lipped Rain Frog as we hiked during the night in search of the Annulated Tree Boa at Yatama Ecolodge. It has a brownish coloration, which would help it camouflage really well against the ground and the leaf litter. Both front and back legs are lightly striped, just barely noticeable when looking from very close. It actually was a pretty common sight in the area, although most frequently heard than seen.

Mottled Snail-eater (Sibon longifrenis)

After a two-hour long night walk in search of the Ghost Glass Frog at Yatama Ecolodge, we were getting ready to go to sleep, when our guide found this Snail-eater close to the entrance gate. Using a stick, he tried to grab it from a branch and succeeded, but the snake became active and only wanted to go away. He managed to carry it away and put it on a leaf close to the ground, where it coiled and became calmer. I approached it with my macro lens and snapped plenty of pictures from many angles. This species has an overall olive color, with red blotches delineated with Black and a few white blotches in between. The eye is large and protruding, with a vertical elliptical iris that becomes circular when entirely open. Like most snakes in the country, they are not venomous and should not pose a threat to humans, however it is best to exercise caution and only handle them if you are trained.

Emerald Glass Frog (Espadarana prosoblepon)

We found this frog during a night time hike in search of the Ghost Glass Frog at Yatama Ecolodge. It acted very docile, barely moving its head down from its upward position. The easiest way to recognize it among the Glass Frog family is by the dark spots on an otherwise uniform green skin. Males feature a blue-green hook, seemingly at the shoulder joint as in the left-hand side picture below; one can only ask what purpose this structure it might serve. The eyes are relatively forward facing, like in most other species in the family.

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 disappeared. 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 drab colors like tan, 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. We found a female resting on a leaf on a night hike, and then a pair in amplexus on another hike through a rocky stream in search of the Ghost Glass Frog, at Yatama Ecolodge.