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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.
Hochstetter’s Frog grows up to 48 mm long. It has partially webbed feet, more warts than the other frogs, and is generally dark brown.
Breeding and Lifecycle
Hochstetter's frog lays large unpigmented eggs in damp situations on the ground, which undergo direct development without a larval stage and the male frogs do not care for their young.
Habitat and Distribution
The most widespread native frog, Hochstetter’s has been sighted around the upper half of the North Island, including at Waipu, Great Barrier Island, the Coromandel, central North Island, and the Raukumara Ranges. This species is semi-aquatic, living on stream edges rather than on land in shady, moist forested areas where the other three species are found. In December 2004 eleven Hochstetter's frogs were found in a fragile, rocky area on Maungatautari Mountain. Subsequent survey work has indicated that there is a small sparse population (including juveniles) in at least two catchments totalling 120 ha on the mountain.
Diet
When mature they feed on insects and spiders.
Threats to Survival
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 sparse species.
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