New Zealand Frogs: Leiopelmatidae

Most people, including the native people who have lived near them for thousands of years, are completely unaware of these quiet little frogs. New Zealand frogs make almost no noise. They may offer a soft squeak if they are roughly handled or some faint squealing sounds during the mating season. Otherwise, they remain silent and even stop moving if a person or some other possible predator comes close. These behaviors, combined with the frogs' camouflage colors and patterns, hide them from all but the most careful observers. In addition, these frogs are mostly nocturnal (nahk-TER-nuhl), which means that they are active at night. The darkness also helps to hide the frogs from sight.

Sometimes, however, predators are still able to find them. If the frogs have the chance to escape by jumping into the water, they will. They swim by kicking one leg at a time instead of kicking both hind legs together, as other frogs do. If they cannot escape a predator, three of the four species defend themselves by raising up on their four legs so they are as tall as possible and turning their bodies to face the predator. This puts forward their largest poison glands, those located in long bumps or ridges behind each eye, so that the attacker's first chomp is a mouthful of bad-tasting poison. Hochstetter's frog does not raise up its body as a line of defense, because its poison glands are on its belly not on its back.

During mating season, most species of frogs find one another by either making loud calls, in the case of the males, or responding to those calls, as the females do. Since New Zealand frogs do not call and even lack a real voice box, scientists think that they find each other by their smells instead. The female lays five to 20 eggs, depending on the species. The developing frog is visible inside the see-through egg capsule. Hochstetter's frog lays its eggs at streamside, and the animals go through a short tadpole stage before becoming frogs. The other three species—Archey's, Hamilton's, and Maud Island frogs—all lay their eggs on land, but under rotting logs or in other moist spots. These frogs go through their tadpole stage while still inside the eggs, so the eggs hatch right into tiny frogs. The male in all three of these species stays with the eggs until they hatch, often covering them with his body. He continues to protect newly hatched young by letting them climb onto his back and legs. Male Hochstetter's frogs do not care for their young.