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.

Dwarf Glass Frog (Teratohyla spinosa)

The Dwarf Glass Frog is the smallest Glass Frog to be seen in Costa Rica, roughly similar in size to a Strawberry Poison Dart Frog, but given its green dorsal skin it is more difficult to spot, specially if they stay motionless on a green leaf; increasing the probabilities of seeing one is the fact that they call from the upper side of leafs, so putting enough attention and following the direction of their call, one might discover an individual. Their eyes are more forward facing than the Dusty Glass Frog, which is the other member of the Teratohyla genus but is a lot larger, also differentiated by the lack of any spots on the Dwarf. An important reproductive characteristic of this species is that the egg clutches are left hanging from the underside of leafs, above a stream so that tadpoles can easily drop to a certain source of water.

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.

Hourglass Tree Frog (Dendropsophus ebraccatus)

The Hourglass Tree Frog receives its name from the dark brown mark on its back, which resembles an hourglass in shape. Overall, it is colored orange and brown, with small light spots on darker areas and small dark spots on the lighter zones. Some individuals are rather patternless and look entirely orange. It is common and widespread in both caribbean and pacific lowlands. This species is arboreal and nocturnal, and can be found in disturbed areas, including gardens close to people’s homes. It is not likely to be confused with any other frog species that inhabit Costa Rica; the other two species in the Dendropsophus genus have a similar orange color, but without the intricate patterns of the Hourglass.

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.

Smooth-skinned Toad (Rhaebo haematiticus)

The Smooth-skinned Toad (or Leaf-Litter Toad as it is called sometimes) is a species of true toad that bears a dead-leaf pattern on its skin, concealing it from most predators when they lie motionless in tree bark or the ground. Furthermore, their lifestyle is nocturnal, so during the day they don’t move much, unless spooked. They rely on that camouflage to be safe, even around streams, where their dull colors can match the colors of some rocks. They are small, around the size of a female Green and Black Poison Dart Frog, but their overall coloration is a dull brown with orange and dark blue patches, making them incospicuous against the brown layer of leaf litter.

Strawberry Poison Dart Frog (Oophaga pumilio)

The Strawberry Poison Dart Frog, along the Green and Black Poison Dart Frog, are one of the common diurnal species that can be found in tropical rain forests in Costa Rica, particularly at the Caribbean side. It is common to go hiking and see these bright red and blue frogs suddenly jump from the trail. Due to the color of their legs, they are also called the “Blue Jeans”, although in Costa Rica some individuals are found that have red legs and arms, and in other countries like Panama there are many more morphs with entirely different color patterns. Regardless of the specific colors, they are very conspicuous and do not camouflage well on the leaf litter that tends to be brown to black. They are tiny when compared with many Tree Frogs.

As with the Green and Black Poison Dart Frog, caution must be taken not to touch these frogs when photographing them with macro lenses, as their skin is poisonous and any contact of their secretions with our eyes, nose or mouth can cause much discomfort. While handling them does not produce any symptons, if one is careless, then it is possible to touch one´s sensible organs with the hands and experience significant effects, up to partial blindness.

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.

Green and Black Poison Dart Frog (Dendrobates auratus)

The Green and Black Poison Dart Frog is one of the species in this family that occurs in Costa Rica, along with the Strawberry Poison Dart Frog and other species, although this species is bigger than the Strawberry. Poison Dart Frogs are diurnal, so it is relatively common to flush them from the floor litter during hiking trips through forested areas. Their contrasting body color is an adaptation meant to signal their poisonous skin to potential predators, helping these frogs escape from danger. Poison Dart Frogs are known because of their ability to withstand ant venom and convert it into their own which means the older the frog, the more poisonous it becomes. Some of these species were used by aboriginal people in South America to kill monkeys and other prey, by rubbing their skin to the arrows that they shoot.

It is normal to see Poison Dart Frogs resting on the leaves of bromeliads, where they usually deposit their larvae, which will develop inside a water pool in the base of a bromeliad leaf. They are more conspicuous when seen on leaf litter, which usually turns brown as the vegetation decays. Also poisonous species like this one are more active during the day. The two times I have had the opportunity to photograph this species, I was careful to keep my distance, as they jumped around quickly and could touch me at any moment. While being touched generally won´t produce any reaction, being careless afterwards and bringing the hands to touch the eyes or the nose after having grabbed one of these can produce significant effects, up to partial blindness.

Cross-banded Tree Frog (Smilisca puma)

The Cross-banded or Tawny Tree Frog is a drab frog with tan to light brown coloration, expanded disks on toes and fingers, and minimal webbing in the feet. They look very similar to the Masked Tree Frog, which is another species in the Smilisca genus. In Costa Rica, it is mainly found in the Caribbean lowlands. It has nocturnal habits and prefers to be on trees, however during the reproductive season, the males descend to the ground and emit their call from the edge of small ponds. Unlike other nocturnal species that I have photographed, this frog would never fully open the eyes. Its position suggests how sleepy they are during the day. They probably rely on camouflage rather than detecting predators and escaping from them.