The frogs are members of the class Amphibia, a group of cold-blooded vertebrate animals whose larval young live in water and breathe by means of internal or external gills, and later metamorphose into an adult form which breathes air by means of lungs. The class includes the frogs, toads, newts, salamanders, and some limbless, wormlike, burrowing forms. New Zealand has a sparse amphibian fauna, limited to three species of native frogs and three frog species introduced from Australia in European times.

The native frogs belong to a genus (Leiopelma) restricted to New Zealand, which shows some of the most primitive skeletal and anatomical features of any known frog or toad.

Leiopelma archeyi occurs only on the Coromandel Peninsula, overlapping sometimes with Leiopelma hochstetteri which are also found in the coastal areas south of the Peninsula and at Warkworth and in the Waitakere Ranges. Leiopelma hamiltoni, the “Stephens Island Frog”, found on Stephens Island in Cook Strait, is now known to occur also on Maud Island in Pelorus Sound. The breeding of these frogs is of particular interest, for the few heavily yolked eggs laid are surrounded by a gelatinous capsule. The frogs undergo most of their development within this capsule and they hatch as well-developed froglets with a tail. At least two of the species are known to lack the free-living tadpole stage usually occurring in frogs. The native frogs are perhaps unique in that they are protected by law.

The introduced Australian frogs all belong to a single genus, Hyla, of a widespread family of tree frogs. The earliest successful introductions took place in 1867 and at least one of the species, the “Golden Bell Frog” (Hyla aurea), has become the most commonly encountered frog in both Islands. A second species, the “Brown Tree Frog” or “Whistling Frog” (Hyla ewingii), is found in Westland and in southern areas of the North Island. This frog produces a distinctive shrill piping call by means of vocal sacs on the throat.

The third species, the “Great Green Tree Frog” (Hyla caerulea), has rarely been found and possibly it is no longer present in New Zealand.

by Richard Essex Barwick, M.SC.(N.Z.), Lecturer, Zoology Department, School of General Studies, Australian National University, Canberra, A.C.T.

• Reptiles, Bellairs, A. d'A. (1957)
• Living Reptiles of the World, Schmidt, K. P., and Inger, R. F. (1957)
• Transactions of the Royal Society of New Zealand, Vol. 86 (1959), “The Life History of the Common New Zealand Skink Leiolopisma zelandica (Gray, 1843)”, Barwick, R. E.
• Dominion Museum Bulletin No. 17 (1955), “The Lizards of New Zealand”, McCann, C
• Tuatara, Vol. VI (1956), “Keys to the Lizards of New Zealand”, McCann, C.
• “Living Amphibians of the World”, Cochran, D. M. (1961)
• Tuatara, Vol. VIII (1961), “Illustrations of the New Zealand Frog Fauna”, Barwick, R. E.
• lb. Vol. VIII (1961), “The Introduced Frogs of New Zealand”, McCann, C.
• Ib. Vol. VIII (1961), “New Zealand Native Frogs”, Stephenson, E. M. (Lists Leiopelma Literature)
• Transactions of the Royal Society of New Zealand, Vol. 84 (1957), “Field Observations on the New Zealand Frog, Leiopelma Fitzinger”, Stephenson, E. M. and N. G.