Our fascinating frogs

Last updated 15:04 09/10/2012

New Zealand is home to four species of native frogs or pepeketua - but most people won't have seen these unusual amphibians. So, today I thought I'd take you on a visual tour.

Maud Island frog2

This beautiful little creature is a Maud Island frog. (Picture: DOC)

As kids, we harboured a real fascination for frogs - when I first learned of their life cycle I was blown away.  My brother and I had tadpoles as pets, until one morning we got up and there were tiny frogs hopping all over the kitchen bench (I think one even ended up in the sugar bowl!). The whole transformation aspect of frogs is an incredible thing to witness. 

The tiny frogs bouncing on the kitchen bench were whistling tree frogs, an Aussie import. They're the ones some of you will be able to hear at night, as the male belts out what I suppose he thinks is an impressive tune. Tree frogs arrived here at Greymouth in 1875. 

We had one that lived in the trees next door to our old house, and we loved hearing him singing before we went to sleep. My Dad and his wife had a pet tree frog called Froggy that lived to the ripe old age of 21! He was a very spoilt frog (his humans caught him flies to feed him well into his dotage) and is still sadly missed.

Whistling tree frog2

Many of us are familiar with the tree frog or whistling frog.

The other froggy imports to New Zealand are Southern (fairly widespread) and green and golden (found north of Gisborne) bell frogs. They're the brightly coloured larger ones that hang around ponds and are sometimes sold in pet shops. The Southern bell frogs are now endangered in Australia due to a worldwide frog disease, the chytrid (pronounced "kit-rid") fungus.  Sadly, chytrid was discovered here in New Zealand about 10 years ago (thought to have arrived with pet frogs).

Green and golden bell frog2

The green and golden bell frogs are beautifully coloured, and are in trouble in their native Australia.

When it comes to the ecology of our native frogs, take everything you thought you knew about frogs and throw it away. Our frogs are extremely ancient, the dinosaurs of the frog world, and have remained relatively unchanged for 70 million years. Our frogs don't croak, don't have an eardrum, have large round pupils in their eyes, and don't have an aquatic tadpole stage to their life cycle! 

Hamilton's frog

This Hamilton's frog is one of the rarest species in the world. There are thought to be only about 300 frogs remaining (on Stephens Island in Cook Strait).

That's right, the defining characteristic of frogs (having a tadpole stage) doesn't occur in our native frogs. Instead the tiny frog embryos develop within their eggs and then hatch out as tiny "froglets". At that point they climb on to their father's back and hitch-hike with him until they are a bit bigger and more able to fend for themselves.

Our native frogs are also fascinating because they don't live in or near the water (except for the semi-aquatic Hochstetter's frog). 

Hochstetter's frog2

The Hochstetter's frog is the only native frog that lives near water.

Instead our frogs prefer to live up in the bush, in dark and moist habitats. They are all nocturnal, so hunt for invertebrates during the evening, and they don't have a long tongue like some frogs; instead they gulp down their prey with a big bite. They also don't move much.The folk at Zealandia can keep tabs on their native frogs simply by returning to the same rocks every year and finding the same frog still underneath - they often don't move more than a few centimetres away from their home.

Having such a sedentary lifestyle has also been the downfall of our amazing native frogs. Predation most likely contributed to the extinction of the three larger native frog species that we used to have in New Zealand. We also know that predators can eat the native frogs we have left (rats eat frogs, but leave their heads untouched - due to glands that secrete something potentially bitter or poisonous). 

Archey

Remains of the Archey's frogs have been found in the Waitakeres after being mostly eaten by rats.

Habitat destruction has had a huge impact - especially in fragmenting frog populations, but also activities like vast deforestation and other large developments that exploit their habitat. The Government's proposal to open up mining in the Coromandel Schedule Four protected areas would have wrecked the tiny native frog populations there, according to national and international frog experts. 

Chytrid fungus has almost been the final nail in the coffin for our native frogs, but there are plenty of scientists, zoos and other frog-lovers working hard to give our frogs a chance.

From a purely anthropocentric perspective, if you don't think our frogs are worth protecting because they're ancient, beautiful, amazing and fascinating, you might like to think about protecting them to save your own skin. Frogs have long been thought to be the "canaries in the coalmine" when it comes to our environment. Frogs have such sensitive skin (a membrane through which they can gain water and nutrients) that any pollutants that affect them might well affect us too. For me, though, I think we're so lucky to have these living fossils in New Zealand, I reckon we should just look after them because they're incredible.

You can see for yourself how cool they are (they might be sedentary, but they can certainly jump - check out the one that leaps off my hand in this video!).

What do you think? Have you ever been lucky enough to see our native frogs? Did you keep pet frogs as a kid? I'd love to hear your froggy tales.

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