Herpetofaunal category
Authority
Lisson, 1830
Previous scientific names
Litoria raniformis
Common names
Southern bell frog
Growling grass frog
Litoria raniformis
Image attribution
Chris Wedding

The southern bell frog was introduced from Tasmania to New Zealand by the Canterbury Acclimatisation Society in the late 1860’s. It is important that any frogs that are held in captivity are not released into the wild as they may pose a threat to our native frogs through transmission of disease, competition, and direct predation.

Description

The largest frog in New Zealand, with some individuals reaching sizes of over 100mm. Similar in colouration to the green and golden bell frog, but with more warts/ridges and less golden colouration. Dorsal (upper) surfaces are bright to dark green with brown spots of thin longitudinal stripes and a paler green stripe running the length of the spine. Occasional individuals are brown. A thin white/cream line runs from the nostril to the eye, above the eye and towards the groin; this stripe is often broken up towards the groin and has a thin black underline. Individuals often have a second stripe running from the upper lip toward the base of the forelimbs. The ventral (lower) surfaces are white/cream, with breeding males having a dark olive brown throat. Armpits and groin can be bright blue. The thighs sport bright blue flash markings; some individuals in the upper North Island have white spots within the blue markings. The species possess the ability to change the colour tone of its skin to aid in camouflage.

Southern bell frog are sexually dimorphic with females being larger than males (females <70-90mm, males <55-65mm), though some individuals grown significantly larger.

Tadpoles are a dark olive green with a white/cream belly; dorsal surface colour lightens as tadpoles grow. The tympanum (external ear structure) is very obvious. Tadpoles typically reach sizes of 70-100mm in length.

Call

Deep and gruff, a fragmented croak with each syllable reducing in duration.

Distribution

Common throughout New Zealand, however, there have been dramatic population declines in southern Canterbury as a result of disease and drought.

Ecology and habitat

Southern bell frog can be found in swamps, ponds and lakes, woodland, shrubland, open and coastal areas. Adult southern bell frog live around breeding sites, are semi aquatic and are active for periods of time during both day and night. Southern bell fogs are nocturnal, although are avid sun baskers. They are agile climbers.

Breeding biology

Breeding takes place in summer with eggs laid in clumps which float for some time before sinking. Breeding grounds include swamps, dams, and permanent lakes.

Diet

The species is voracious and carnivorous, consuming invertebrates such as crickets, flies, grasshoppers; freshwater crayfish and slugs; other frogs (including cannibalisation of con-specifics) and lizards.

References

  • Gill, B.J., & Whitaker, A.H. (2007). New Zealand frogs and reptiles. Auckland: David Bateman Limited.
  • Jewell, T. (2011). A photographic guide to reptiles and amphibians of New Zealand. Auckland: New Holland Publishing.
  • Pyke, G. (2002). A review of the biology of the Southern Bell Frog Litoria raniformis (Anura: Hylidae). Australian Zoologist, 32, 1, 32-48.