As their name suggests, tree frogs are mainly arboreal, spending most of their time above ground on trees or other plants. To support this arboreal lifestyle, tree frogs have large, sticky toe pads that allow them to climb smooth surfaces, maneuver along thin branches, and scale flat rocks and plant leaves with ease. Nearly all species are nocturnal. This explains their greatly enlarged eyes, which help them see at night when they are active and give many an almost unworldly appearance, like something you could imagine beamed down from outer space. They are often heavily camouflaged to help them blend into their surroundings, whether lichen-covered bark or a large, uniformly green leaf. Not only are tree frogs camouflaged, but many species also possess the ability to change color depending on the environmental conditions to which they are exposed. Light levels, temperature, humidity, and their surroundings can all determine the color of a tree frog.
Tree frogs occupy many different environments, from humid rain-forests to hot, arid regions. Tree frogs live on all continents except Antarctica. The tropical rain-forests of Central and South America are home to the greatest diversity of tree frog species, and contain nearly three-quarters of the large tree frog family Hylidae. Some tree frogs live exclusively in the canopy, never descending to ground level. Others tend to congregate around bodies of water, spending much of their time on emergent vegetation and small bushes or trees that surround ponds. Still others live in dry, desert regions, where they depend on unique adaptations to conserve water to survive.
As with all amphibians, water is critical for tree frogs and limits where they can be found. Some species utilize water-filled cavities in trees; others rely on streams or ponds. Rainfall is also an important water source for most tree frogs, and after a heavy rain many frogs emerge from hiding to utilize the water that has collected around them. Unlike humans, tree frogs do not drink with their mouths, but instead absorb water through their permeable skin by soaking in it to stay hydrated.
Tree frogs depend on water to breed. Many species are seasonal breeders, and an increase in rain indicates that it’s time to reproduce. Eggs can be laid in water or on floating plants, but they are also often deposited above water on leaves, or next to water on other vegetation, depending on the species. Tree frogs have an aquatic larval stage during which they are called tadpoles. Throughout this period they are fully aquatic, usually grazing on algae and detritus, until they metamorphose and leave the water. As tadpoles, tree frogs are very vulnerable to predators. Certain insects, insect larvae, fish, and even other tadpoles will eat them. Many tree frogs lay large numbers of eggs at one time to help ensure that at least some of their offspring survive past the larval stage.
Tree frogs use their enlarged eyes to locate food, relying on movement to catch their attention and initiate a feeding response. Live insects and other invertebrates are their preferred diet. Some larger tree frogs also feed on small lizards, and there are even species that specialize in feeding on other frogs. Small mammals and baby birds can be consumed by very large species.