Red-Eyed Tree Frog

Red-eyed tree frog（圖片來源：Geoff Gallice from Gainesville, FL, USA，採用 CC BY 2.0 授權）

The red-eyed tree frog (Agalychnis callidryas) is one of the most iconic tree frog species, renowned for its striking red eyes and vivid coloration. It is native to Central America and the northern regions of South America, including Mexico, Costa Rica, Panama, and Colombia, where it inhabits tropical rainforests, particularly humid areas near rivers.

This species is a nocturnal arboreal amphibian. During the day, it rests pressed against leaves, using its green dorsal coloration as camouflage. When threatened, it suddenly opens its bright red eyes and reveals its orange feet along with blue and yellow flank stripes, creating a startling display that deters predators.

Adult males measure approximately 5 to 6 cm in body length, while females are larger, reaching 7 to 7.5 cm. They have slender limbs and adhesive toe pads that allow them to cling securely to leaves and branches. In the wild, their lifespan is about 5 years, but under proper care in captivity, they may live 8 to 12 years.

In nature, their diet consists mainly of small live arthropods such as moths, mosquitoes, and flies. Occasionally, they may consume small amphibians or even tadpoles of their own species. Tadpoles are more omnivorous, feeding on algae, plankton, and organic debris.

Breeding typically occurs during the rainy season. Females lay clusters of approximately 30 to 50 eggs on the underside of large leaves above water. The eggs hatch within 5 to 8 days, at which point the tadpoles drop into the water below. They develop for 2 to 3 months before metamorphosing into juvenile frogs. Some embryos can hatch prematurely in response to environmental disturbances or predators. This sensitivity to external cues is known as phenotypic plasticity and serves as an important survival strategy.

Housing Requirements in Captivity

Because red-eyed tree frogs are arboreal, their enclosure must replicate a humid, vegetation-rich tropical rainforest environment. A vertically oriented glass terrarium is recommended. A single adult requires at least a 45 to 50 cm enclosure in length, width, and height, while 3 to 4 individuals should be housed in an enclosure of at least 60 to 70 cm.

The enclosure should provide abundant vertical climbing structures, including live or artificial plants, branches, and cork bark. Leaf coverage should be included to offer shelter, with at least one hiding spot in both warmer and cooler areas.

Temperature should be maintained at 25 to 27°C during the day and 24 to 26°C at night. Prolonged exposure above 27°C should be avoided to prevent heat stress. Heating devices must be paired with thermostatic control, and high-temperature heating rocks should never be used due to the risk of burns.

Humidity should be kept at 70 to 80%, with misting performed 1 to 2 times daily. A shallow water dish should be provided for soaking. Water must be dechlorinated, either by boiling for 15 to 20 minutes or using a dechlorinating agent, and should be replaced and cleaned daily.

A light cycle of 10 to 12 hours per day should be provided. Low-intensity UVB lighting (2.0 to 5.0) can be used to promote vitamin D3 synthesis and calcium absorption. UVB bulbs should be replaced every 6 to 9 months. The substrate may consist of moisture-retentive materials such as coconut fiber, moss, or coarse bark. Fine particulate substrates such as sand or gravel should be avoided to prevent ingestion and intestinal blockage. A tightly fitted mesh lid is essential to prevent escape, and sharp or rough materials should be avoided to protect their sensitive skin.

Feeding Conditions

Red-eyed tree frogs are carnivorous and feed primarily on live insects. Common food items include small crickets, cockroaches, silkworm larvae, and mealworms. Prey size should not exceed the width of the frog's head.

Individuals smaller than 7 cm should be fed every 1 to 2 days, while larger individuals can be fed every 2 to 3 days. Each feeding should consist of approximately 3 to 6 insects to avoid obesity.

Before feeding, feeder insects should be gut-loaded with calcium-rich foods and vegetables such as carrots and dark leafy greens. The insects should then be dusted with reptile calcium powder containing vitamin D3, along with a multivitamin supplement. Juveniles require daily calcium supplementation, while adults should receive calcium 2 to 3 times per week and vitamins once per week.

These frogs respond only to moving prey, so live food must be provided. Insects can be offered using tweezers to create slight movement or released directly into the enclosure. Uneaten prey should be removed after feeding to prevent disturbance or injury to the frogs.

Breeding Conditions

Breeding in captivity is achievable but requires simulation of rainy season conditions. This can be done by increasing nighttime humidity to around 90% and increasing misting frequency. Large leaves suspended above water should be provided as egg-laying sites.

A clean, dechlorinated shallow water container should be placed beneath the leaves to collect the hatched tadpoles. Once the tadpoles fall into the water, they should be transferred to a separate enclosure to prevent predation by adult frogs.

During breeding, males engage in amplexus with females. The female lays 30 to 50 eggs on the underside of leaves, and the male fertilizes them externally. The eggs must remain in a high-humidity environment and will hatch within approximately 6 to 8 days. The tadpoles then fall into the water and continue developing.

During the tadpole stage, they feed on plankton, algae, and small organisms. After 2 to 3 months, they metamorphose into juvenile frogs. Juveniles should initially be fed fruit flies or small crickets, with continued calcium and vitamin supplementation. Sexual maturity is typically reached after about one year.

The eggs of red-eyed tree frog（圖片來源：Brian Gratwicke，採用 CC BY 2.0 授權）

Embryos within the eggs of the red-eyed tree frog（圖片來源：Geoff Gallice from Gainesville, FL, USA，採用 CC BY 2.0 授權）

Preventing Invasive Spread

Due to their popularity in the pet trade, red-eyed tree frogs are widely bred in captivity in many countries. However, if released into non-native environments, they may disrupt local ecosystems. They can rapidly adapt to humid environments and prey on native insects and small amphibians, potentially altering local population structures.

Additionally, they may carry pathogens such as chytrid fungus or viruses such as ranavirus, posing a threat to native amphibian populations. Therefore, keepers must follow these principles:

1. No release into the wild: If unable to continue keeping the animal, transfer it to an experienced keeper or a legal animal shelter.

2. Secure enclosure design: Ensure that enclosures are properly sealed to prevent escape.

3. Hygiene and quarantine: Avoid contact with wild amphibians to reduce disease transmission risk.

4. Education: Promote awareness among other keepers about the ecological risks of releasing captive animals.

Author: Shui-Ye You