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.
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.
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.
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.
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.
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.
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.
This species has a mostly green body, with light blue patches in some dorsal parts. The eye is yellow with an horizontal black pupil. The disks at the end of the fingers are expanded, featuring a yellowish coloration. The best field mark for identification is the red webbing between its fingers, just like its name suggests. It is mainly nocturnal, hence not commonly seen during the day. It is curious how the skin color of this frog species changes from day to night time. During the day, the color is similar to a turquoise, while in the night the skin turns yellowish.
A friend of mine found an individual on the edge of the trail that leads to the Agami colony at Pacuare Reserve. It was late in the day, so it was still sleeping and let me have a half-hour photoshoot session with it without a single sign of being disturbed. One of the shots was taken only using natural light during a fairly strong wind that constantly moved the leaf up and down. I thought of artificially creating the night, although the frog was still sleeping. To create the black background on the second picture, I lighted the frog from very close using a bike lantern. The light did not need to be very powerful, since at macro distances the difference between the light intensity at the subject and the background can be exaggerated.
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.
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.