A guide to New Zealand’s frogs
How much do you know about the six different native and exotic frog species found in Aotearoa?
Weird and wonderful facts about our native and introduced amphibians.
The New Zealand frog fauna includes three native species (Leiopelmatidae) and three introduced species (Hylidae). The native species all belong to the genus Leiopelma, an ancient lineage of primitive frogs found only in New Zealand. Their closest relatives are the North American tailed frogs in the genus Ascaphus (Ascaphidae).
The Ascaphus frogs (there are two species) share the primitive traits of Leiopelmatidae, distinguishing both families from all other species of frogs, including vestigial tailwagging muscles, amphicoelous vertebrae and nine presacral vertebrae (most frogs have eight).
Leiopelma frogs also lack tympana (eardrums), eustachian tubes and vocal sacs. This limits their ability to vocalise; most other frogs usually emit loud social calls during the mating period.
Instead, our native frogs probably communicate in a similar way to salamanders, using chemosignals that convey information about size and individuality.
Leiopelma frogs are all strictly nocturnal, and highly cryptic. They predominantly live in dense damp native forest or close to small streams. Two species – Hamilton’s ( L. hamiltoni) and Archey’s frogs ( L. archeyi)) – are primarily terrestrial but Hochstetter’s frog ( L. hochstetteri) is semi-aquatic, usually living in and on the edges of small, shaded stream tributaries (although also sometimes found away from streams on the forest floor).
The reproduction of the two terrestrial species is quite specialised – there is no free-living tadpole stage and development occurs entirely within the egg capsule. Eggs are unpigmented, about 5mm in size, and contain a large yolk. During spring, females lay the eggs in clusters of up to 19 eggs in dark, damp sites such as under logs and rocks. The male guards the eggs until they hatch. The tiny, tailed froglets then climb onto the back of the male, who guards them for several weeks while they complete their development.
The reproductive strategy of Hochstetter’s frog differs markedly, with strings of eggs (up to 22) laid in shallow depressions with trickling water. Eggs hatch at a relatively early development stage into larvae with partially developed limbs and well-developed tail fins that enable them to swim. They do not feed, and remain in the shallow water while they develop into small frogs.
All Leiopelma frogs persist in small fragmented populations on the North Island’s mainland or on islands in Cook Strait and the Marlborough Sounds. Two of our three native frogs (both of the terrestrial species, Hamilton’s and Archey’s frogs) are listed as threatened on the IUCN (International Union for Conservation of Nature) Red List. All three species are listed in the top 100 Evolutionarily Distinct and Globally Endangered (EDGE) amphibians, with Archey’s frog topping the list.
All three introduced species are from Australia. The two Ranoidea bell frogs – green and golden bell frog ( R. aurea) and southern bell frog ( R. raniformis) – were deliberately introduced by acclimatisation societies during the 1860s, and the brown (whistling) tree frog ( Litoria ewingii) by a private individual in 1875. These species have adapted well to New Zealand conditions, and are now widespread and common. The green and golden bell frog has become very rare in its native Australian range, to the degree that IUCN has listed it as vulnerable.
The introduced species are easily distinguished from the native frogs by the clearly visible tympanum, their loud mating calls and a large (60-100mm long) free-living tadpole stage. The spread of these species is of concern because of their potential to transmit pathogens (chytridiomycosis) to native frogs, and they are also known to prey upon native frogs and lizards.
Our native frogs belong to an ancient lineage of primitive frogs found only in New Zealand.
HOCHSTETTER’S FROG
DESCRIPTION Males up to 38mm; females, 47mm. Dorsal surface is mostly red-brown or green-brown, with or without dark bands. Lateral surfaces are brown or red-brown, often with sparse pale flecks. Ventral surface is yellow-brown. Skin is granular and covered with raised glandular tubercles.
Eye colour is olive-green, hazel or golden brown. It has short fingers and toes, and distinctive webbing on hind toes. WHERE North Island only, from south of Whangarei to Maungatautari and the Coromandel Peninsula, and on East Cape. Also on Great Barrier Island (Aotea Island).
They live in coastal, lowland and montane/subalpine areas. Semi-aquatic, they are usually found in or near small streams and tributaries, within shaded native forest. Occasionally found long distances away from streams in damp native forest as they are able to survive in some modified habitats (shaded streams in farmland and exotic plantation forests). They also take refuge in damp crevices, and under stones, rock piles or logs, and thick leaf litter. NATURAL HISTORY Nocturnal, with very limited daily movements. It can squeak or chirp when disturbed and relies on camouflage to avoid predators. It will jump into streams or swim to escape. It feeds on spiders, beetles and mites.
Females lay eggs from late September-May; these hatch after 40-60 days. Larvae have partially developed limbs and well-developed tail fins for swimming. They remain in shallow water for 4-8 weeks while developing into froglets. They reach maturity at 3-4 years, with adult longevity of more than 30 years. Of the 13 genetically distinct populations, Otawa forest frogs (Bay of Plenty) are the most isolated, with the smallest area of occupancy, and most genetically distinct.
HAMILTON’S FROG
DESCRIPTION Males up to 43mm; females up to 52mm. Dorsal surface is variable in colour, ranging from uniform dark blackish brown to light brown with irregular darker patches, blotches or mottling.
A dark band extends from the tip of its snout to nostril, continuing through eye and over shoulder, below dorsolateral ridge. Some light-coloured individuals have a dark, backwards-pointing triangular marking between their eyes. Hind legs may be marked with oblique dark bands. Eyes are mostly black with a lighter golden arch in upper surface. Unwebbed feet; digits are slender, without enlarged distal pads. WHERE Restricted to islands in the Marlborough Sounds and Cook Strait. A small population was translocated to a sanctuary in Wellington. It thrives in coastal, lowland areas, occupying vegetated boulder banks beneath the forest canopy. It shelters in damp crevices and beneath rocks during the day, emerging at night to feed. NATURAL HISTORY Nocturnal and terrestrial, it is relatively sedentary and generally ranges over just a few metres. Primarily insectivorous but will consume other invertebrates.
Frogs mate between October and December. The male occupies oviposition sites and fertilises 1-19 unpigmented eggs as they are laid in damp ground. The males guard these eggs for 14-21 weeks. Froglets, which hatch out with a small tail, are carried on his back. Presumably this keeps the young moist, protected from predators, and reduces fungal or microbial infections. Froglets mature in 3-4 years; adults are long-lived (over 40 years).
ARCHEY’S FROG
DESCRIPTION Males up to 31mm; females up to 37mm. They are considered New Zealand’s smallest and most beautifully marked frog. Dorsal surface is light to dark brown, green-brown or green (uncommon); most with scattered dark blotches.
They have some black stripes or markings on the dorsal surface of fore- and hind limbs, black markings under each eye and black upper lip. Eyes are mostly black with a lighter golden arch in upper surface. Feet are unwebbed; digits slender, lacking enlarged distal pads. WHERE Coromandel Peninsula and Whareorino Forest, west of Te Kuiti. It lives in lowland and montane/ subalpine areas, occupying damp native (cloud) forest, often on ridges away from creeks. It takes refuge under rocks or rock piles and beneath logs during the day, emerging at night, moving over the ground, short stature vegetation and logs to feed. NATURAL HISTORY Nocturnal and terrestrial, but it may climb up trees or shrubs. It is unable to call but can squeak or chirp. A poor jumper, it may assume a rigid stance – raised body and extended legs – when disturbed or threatened. It relies on body colouration for camouflage.
Mating occurs from September to November. Females lay 4-15 large unpigmented eggs (8-11mm) per clutch over summer in damp soil beneath rocks or logs, or in hollow ponga trunks. Eggs are guarded by the male and hatch as froglets (with tails) that climb on to his back. They stay with him for several weeks until metamorphosis is complete. Froglets mature in 3-4 years; these frogs can live for more than 35 years.
All three exotic species of frog found in New Zealand are from Australia. They have adapted well to conditions here, and are now widespread.
GREEN & GOLDEN BELL FROG
DESCRIPTION Males measuring up to 60mm; females, 80mm. Dorsal surface relatively smooth and emerald and/or golden brown, with irregular and variable golden bronze blotches.
A cream-coloured dorsolateral stripe, edged below by a narrower black line, extend from nostril to eye and over tympanum towards the groin. Another cream-coloured stripe runs over the upper lip to the base of the forelimb. Tympanum is distinct and clearly visible. Limbs are green or bronze with golden blotches. Breeding males may have dark olive throat. Armpits and groin are bright blue; flash markings on thighs also blue. Its front feet lack webbing but the hind feet are almost fully webbed; finger and toe discs are expanded but only slightly wider than digits. WHERE Northland to East Cape and south Taranaki, and small isolated populations in Southland. It lives in coastal, lowland and montane/subalpine areas, and is also found in farmland and other settled areas close to swamps, lakes, ponds and slow-flowing streams. NATURAL HISTORY Primarily active at night but frequently active by day, it is terrestrial, arboreal and semi-aquatic.
The frog spawns in spring to early summer, with females depositing eggs in a floating gelatinous mat in still water. These sink after 6-10 hours.
Tadpoles hatch in two days and froglets appear after two months.
Tadpoles feed on bacteria, algae and organic detritus. Adults forage at night, especially in warm damp evenings, feeding on almost anything, from insects to other frogs and lizards.
SOUTHERN BELL FROG
DESCRIPTION Males up to 65mm; females, 95mm. Dorsal surface is green or brown, with varying degrees of brown spots, blotches or streaks. Usually seen with a pale green mid-dorsal stripe. Numerous large tubercles, warts and skin folds on dorsal and lateral surfaces.
A dorsolateral cream-coloured stripe (often fragmented), bordered below by a thin black line, extends from nostril to eye and over tympanum towards groin. A cream stripe also runs over the upper lip to the base of the forelimb. Tympana is clearly visible. Limbs are blotched with green or brown. Breeding males may have dark olive throat. Armpits and groin are bright blue; flash markings on thighs also blue (may be overlaid with white spots in some North Island populations). Front feet lack webbing but hind feet almost fully webbed; finger and toe discs generally not wider than digits. WHERE Distributed widely across the North and South Islands, in alpine, montane/subalpine, coastal and lowland areas; associated with bodies of still water (dams, ponds, swamps, marshes) and terrestrial vegetation on the edges of bushland, farmland or residential areas. NATURAL HISTORY Primarily active at night but frequently active by day, it is an avid sun-basker.
Spawning occurs in spring to early summer, with egg masses sinking in water after floating for a few hours. Tadpoles hatch in 2-4 days; froglets appear after 2-3 months. Tadpoles feed on bacteria, algae and organic detritus. Adults are opportunistic predators, feeding on invertebrates, other frogs and lizards.
BROWN (WHISTLING) TREE FROG
DESCRIPTION Males up to 37mm; females, 49mm. This small brown tree frog has a loud, harsh call. Dorsal surface varies from pale fawn to brown or olive-green. Light brown or golden triangular marking sit on the anterior region of its head, and a dark brown stripe runs from nostril through eye and tympanum to axilla, with a pale cream or white stripe below extending over upper lip towards forelimb.
Flash markings on the thighs are bright orange. Armpits and groin are yellow-green. Fingers and toes with expanded distal pads are partially webbed. WHERE Distributed widely across the South Island and patchily distributed across the North Island. Also present on the Chatham Islands.
Living in coastal, lowland, montane/subalpine and alpine areas, it can be found in temporary and permanent water in urban areas, farmland, vegetated sand dunes, tussock grasslands, alpine herbfields and pavement. Adults are mostly found in low, dense vegetation, rocks or logs. They may live around breeding ponds or up to 1km away. NATURAL HISTORY These frogs are capable of surviving after being frozen. Though nocturnal, they also commonly sun-bask. Terrestrial and arboreal, they can breed at any time of the year though calling may occur throughout the year (not just during breeding season). Most water bodies (except fast-moving streams) can be used for breeding. Eggs are laid in clumps on submerged vegetation, and hatch in 7-29 days, depending on temperature. Adults feed on small invertebrates including snails.