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Photo: Pady Ryan, Ryan Photographic |
As giant meat-eating lizards began to stomp through the jungles, frightening the life out of their prey, small species of frog already inhabited the planet. New Zealand was then just floating away from Gondwanaland and the frogs, not needing to evolve, didn't. So they sat there with their unique features:
- round rather than slit eyes,
- hatching straight into an almost fully-formed frog instead of tadpoles,
- no external ear drums, and
- not croaking regularly like most other frogs.
Scientists believe that these frogs evolved about 200 million years ago, making them as unique as the tuatara, and the most ancient frog species in the world. They are small, nocturnal, and camouflage themselves well making them very hard to see.
These frogs are generally brown with a pale patch on the snout, and the upper part of the iris is bright gold. The hind limbs are fairly short, and the feet are not webbed. They can reach 50 mm in length. Females tend to be larger than males, but the sexes are otherwise indistinguishable.
Breeding and Lifecycle
Females lay up to 20 large, yolk-filled eggs in cool, damp depressions under cover on the ground. The whitish larvae undergo development within the egg capsule and hatch when fully metamorphosed. The male attends the eggs and froglets, which clamber onto his back and legs.
Habitat and Distribution
Only found on Maud Island in the Marlborough Sounds. Boulders, logs, and rocks toward the lower, damper, less steeply sloping part of the forest, with no permanent streams or seepages are where the frogs are most abundant. In 1997 three hundred Maud Island frogs were transferred to Motuara Island - establishing a second population of the frog in another location is insurance against a disaster, such as fire, wiping out a sole surviving population.
Diet
The diet consists of terrestrial insects.
Threats to Survival
New Zealand native frogs were once spread throughout both the North and South Islands. The four remaining species have declined significantly in range and in numbers, as land has been cleared of forest and predators have been introduced. Frogs are vulnerable to many introduced predators such as rats and cats.
Forestry and agriculture also take a major toll on frog populations and roads and agricultural fields are significant barriers to amphibian’s movement. The apparently safe herbicide "Roundup" is extremely toxic to tadpoles and adult frogs and can cause developmental abnormalities or fatalities. This herbicide is widely used by farmers, foresters and gardeners in New Zealand.
Chytrid fungus was first detected in Canterbury in November 1999, by September 2001 it was detected in frogs in the Coromandel region. The spread of this fungus poses a serious threat to this nationally endangered species.
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