Hauturu – Searching for frogs

There are three species of native New Zealand frogs (Leiopelma), found nowhere else in the world. They come from an ancient lineage of primitive frogs with attributes not found in modern frogs: they don’t croak, they have no eardrums, their young hatch as froglets (not tadpoles), they are nocturnal and long-lived (30 years or more). All three species are endangered due to habitat loss and predators. They have been protected since 1922. The three species are much smaller than introduced frogs. They are between 30mm and 50mm long compared with the introduced Southern Bell frog, which is between 65mm and 95mm. The colouring and markings of native frogs make for good camouflage.

Archey’s frog is now confined to the Coromandel Ranges and a forest west of Te Kuiti. It is the smallest of the three species and lives in moist native forest and mist-shrouded ridges. It doesn’t need streams and lives under stones and logs, emerging at night to feed on insects.

Hamilton’s frog is found on several islands in the Marlborough Sounds and is the largest of the three species.

Hochstetter’s frog is found between Whangarei and the Bay of Plenty. It is known to be present on Great Barrier Island and Coromandel. It tends to live in shaded creek edges within the native forest up to about 800m above sea level. It is semi- aquatic and nocturnal. Its daytime habitat is likely to be under stones at the stream edges.

In January this year, Dick Veitch, an ex-wildlife officer, led an extensive frog search on Hauturu. It was thought possible that either Archey’s frog or Hochstetter’s might be present on the island, although they had never been recorded there in the past. Both species are notoriously hard to find. With the removal of kiore (Polynesian rat) in 2004 it was thought that sufficient time had elapsed for a small population to grow to a size where some might be found if they were present.

Dick was ably assisted by a group of searchers, all of whom had had some experience with native New Zealand frogs. The outcome was that two thirds of the island streams were searched, either in part or in full. Some certainly showed good habitat for our native frogs, but sadly ,no frogs were found. It was, however, an opportunity to visit some areas of the island that are rarely visited. Banded kokopu and longfin eels were found in several of the streams. There were also several sightings of the rare forest ringlet butterfly. The Hauturu Supporters’ Trust and the Auckland Museum helped fund the research.

Lyn Wade, Little Barrier Island Supporters Trust
www.littlebarrierisland.org.nz