Tree frogs occupy a world of leaves, bark, water, and changing light. Their colors reflect many different pressures rather than one simple purpose.
Green is excellent camouflage
Many species blend into leaves when resting. Patterns and small color changes can help the outline disappear.
Bright colors may carry a warning
In some frogs, conspicuous coloration signals chemical defenses. Predators that learn the association may avoid similarly colored animals later.
Amphibians reveal environmental change
Because their skin is permeable and their life cycles often depend on both land and water, frogs can be sensitive to pollution, disease, and habitat disruption.