The Giant Gladiator Frog (Boana boans) occurs along tropical rivers from Panama throughout lowland South America. When waters recede during the dry season, stretches of moist sand become the stage for impressive amphibian combat. Male B. boans descend from the trees to create and defend circular breeding pools. Wherever they occur, their sonorous "BWACK, BWACK, BWACK" calls are an integral part of the night. The large male in the image was photographed along Amazonian Peru's Momόn River.