Red-eyed Treefrog

Red-eyed Treefrog, Agalychnis callidryas

Red-eyed TreefFrog, Agalychnis callidryas. Photograph taken within the confines of the LaPaz Waterfall Gardens National Park, Alajuela, Costa Rica, February, 2012.  Photograph courtesy of Carol Snow, Del Mar, California.

The Red-eyed Treefrog, Agalychnis callidryas, is a member of the Phyllomedusidae family of Leaf Frogs. The Phyllomedusidae family consists of sixty-five members placed into eight genera. There are thirteen species in the Agalychnis genus. The Red-eyed Treefrog is known in Mexico as Rana-de Árbol Ojos Rojos.

Red-eyed Treefrogs are easily recognizable by their big bulging red eyes and bright lime green bodies. Their distinctive eyes are a type of defense mechanism known as startle coloration. When Red-eyed Tree Frogs close their eyes, their green eyelids and body help them to blend in with their leafy environment. If approached, the sudden flash of red as they open their eyes will momentarily paralyze their predator, allowing them a few seconds to escape. Red-eyed Treefrogs can become a dark green or reddish-brown color according to their mood or environment. They have smooth skin and their sides are light blue with vertical white bars. The ventral surface of their limbs are also light blue, however, their belly and throat are white. Their feet are bright orange or red with four toes on their front feet and five toes on their hind feet. Their toes are elongated with cup-like foot pads, making them excellent climbers. Sexual dimorphism is displayed with females growing up to 8 cm (3.1 inches) and males growing up to 5 cm (2.0 inches) in length. Tadpoles of this species are relatively large, reaching 4 cm (1.6 inches) to 5 cm (2.0 inches) in length. They have long, narrow tails and their skin is pale-gray dorsally with blue-gray on their sides.

Red-eyed Treefrogs are polyandrous and only breed during the rainy season, as their eggs require access to wet conditions. Males produce croaking noises to attract the attention of females, and will fight with other males to have a chance at mating with a female. As a part of the mating process, the pair of frogs engage in amplexus. This is a process in which the male latches onto the female’s back on the underside of a leaf, ensuring that the eggs can become fertilized as they exit the female and adhere to the leaf. Eggs are laid on a leaf that hangs over a pond or small body of water. No additional parental care is provided by the male or female after fertilization. Gestation lasts for approximately 45 days and when the eggs are ready to hatch, the tadpoles inside start swirling around vigorously. This activity breaks each egg open, releasing the tadpoles down the leaf and into the water below. As tadpoles, they can only survive for up to 20 hours on land, so it is vital that they quickly find water. The tadpoles live in water and feed on small insects until they metamorphosize into brown froglets, after approximately 75 days. At this time, they leave the water and live in the trees. The young mature in two years, but will not begin mating for another two years. The Red-eyed Tree From have a live span of up to five years in the wild and between eight and twelve years in captivity. 

Red-eyed Treefrogs are nocturnal carnivores. Their diet consists of a variety of insects including flies, grasshoppers, and mosquitos. Additionally, they have been known to consume one another during their tadpole stage of life. In turn, they are preyed upon by several predators that vary according to their stage of life. As embryos, they face predation from several types of wasps and snakes. During their tadpole stage, they are predated upon shrimp, large fish, and large aquatic insects. As adults, they are preyed upon by large spiders, snakes, birds, and bats. Red-eyed Tree Frogs begin perceiving information from their environment even before they hatch. Embryos use cues, such as vibrations, to determine whether or not they should delay their hatching time. When they are post-metamorphosis, they can communicate using their colors and vocalizations. While communicating with another member of their species, they also tend to shake tree branches in order to send vibrations. 

In Mexico the Red-eyed Treefrog occurs from the Atlantic slopes of Veracruz and northern Oaxaca, and south through Nicaragua and Costa Rica, and along the Caribbean slope of Panama and northern Colombia. They are found from sea level to elevations of 1,700 m (5,600 feet). They inhabit tropical lowland and montane forest where there is a continuous forest cover. They can also inhabit secondary forest and heavily degraded areas as long as there is tree cover close to ponds.

The Red-eyed Treefrog may be confused with the Blue-sided Leaf Frog, Agalychnis annae, due to their similar appearances and overlapping ranges. These species can be differentiated visually and geographically. While the Blue-sided Leaf Frog is also green dorsally with blue sides, they lack the vertical white bars that are present on the Red-eyed Tree Frog. Additionally, the Blue-sided Leaf Frog has orange eyes instead of red. The Blue-sided Leaf Frog is also only found in northern and central Costa Rica at elevations up to 1,600 m (5,200 feet).

From a conservation perspective, the Red-eyed Treefrog is currently considered to be of Least Concern due to their wide distribution, tolerance of a degree of habitat modification, and presumed large population size. They are currently threatened by deforestation and degradation from agricultural activities, urban expansion, and logging. However, this species does well in areas where there has been selective logging and they are considered to be fragment-tolerant. Wild subpopulations in Costa Rica, Nicaragua, and Panama are threatened by capture for the international pet trade. Diseases, such as Ranavirus in tadpoles and Chytrid Fungus in adults, are also regular threats.