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Amphibians and reptiles are significant components of many tropical communities. They usually occur in relatively high population densities, which often exceed the biomass of other vertebrates (Vitt 1990). This makes them important predators and thus regulators of the arthropod fauna. Their high biomass provides a prey base in many habitats as well. Besides this central position in the food web of many ecosystems, amphibians and reptiles are functionally important as biological indicators of environmental degradation owing to their specific habitat requirements and their limited ways to disperse. With the ever-increasing devastation of tropical rainforest, the selection of protected areas, which represent pristine ecosystems, becomes more and more urgent. Active conservation of such ecosystems with their specific species and their interactions is exclusively possible if this conservation is based on an extensive knowledge of the ecosystem concerned.

Seasonal rainfall affects tropical forest dynamics and behavior of species that are part of these ecosystems. The positive correlation between amphibian activity patterns and rainfall has been demonstrated repeatedly. Members of Dendrobatidae, a clade of Neotropical dartpoison frogs, are well known for their habitat use and behavior during the rainy season, but their behavior during the dry season has received little attention. We studied habitat use and diet of the dendrobatid frog Dendrobates tinctorius in French Guiana during the rainy and dry seasons. Unlike many other dendrobatid frogs, D. tinctorius does not maintain territories for the entire rainy season. Both sexes colonize recently formed canopygaps and stay in these forest patches for only a few weeks. The frogs in these patches consume a great diversity of prey, consisting of ants, beetles, wasps, insect larvae, and mites. During the dry season, frogs move to retreat sites in mature forest, such as palm bracts and tree holes. The frogs are less active and consume fewer prey items in the dry season, and they consume fewer wasps and insect larvae, but more termites. Ants are the most common prey items during both the wet and dry seasons. We discuss the effects of shifts in seasonal habitat use on the territorial behavior of dendrobatid frogs.