Cuvier—An Island Restored

Forest and Bird, Issue 184, 1 May 1972, Page 7

Cuvier—An Island Restored

CUVIER ISLAND, lying in the outer Hauraki Gulf 25 miles east of Cape Colville, the northern extremity of the Coromandel. Peninsula, has a history which would make it excellent material for a "before and after" advertisement.

By

D. V. Merton

Wildlife Service, Department of Internal Affairs

WHEN officers of the New Zealand Wildlife Service, Department of Internal Affairs, first visited the “old” Cuvier in August 1953, overgrazing by heavy populations of feral goats in addition to domestic sheep and cattle, had seriously affected the vegetation. The North Island saddleback had disappeared — presumed exterminated by the large numbers of feral cats — and other birdlife was poor.

Today, however, the “new” Cuvier tells a vastly different story. After a decade of management this island reserve is now well on the way toward complete rehabilitation; the goats and cats are gone, which has allowed vigorous regeneration of vegetation, and the saddlebacks, which were reintroduced in 1968, are flourishing with other birdlife. Little History Recorded Little is recorded about the history of Cuvier Island. Though it was certainly inhabited by

Maoris in 1824, when it was discovered by d’Urville and named after a famous French naturalist of that period, Maori lore supported by archaeological findings suggests that.it could possibly have been inhabited discontinuously from an early date even before the fleet period migration of 1300 A.D. The area of the island — Repanga to the natives — is 481 acres, of which 58 acres are lighthouse and radar beacon reserves and the remaining 423 acres are a flora and fauna reserve. The terrain is hilly, rising to 755 ft above sea level, and most of the coastline is cliff bound. Mixed coastal forest covers about 250 acres of the land, and several giant specimens of pohutukawa and puriri have managed to survive in spite of indications of widespread burning in pre-European times.

Though Maori activity undoubtedly had some effect on the island’s flora and fauna (areas of forest and scrub were burnt to accommodate cultivations and pas, and the Polynesian rat or kiore was introduced), there was little permanent damage done. It was left to the Europeans who followed them to disrupt the ecological balance seriously.

The introduction of goats dealt a major blow to the whole structure of vegetation cover, and some previously recorded plant species (1896) disappeared and more palatable varieties ceased to regenerate. The understorey, too, was destroyed, which enabled wind to damage the larger trees. Dense, luxuriant scrub covering steep coastal faces was transformed into eroding grasslands. Depredations of Cats As if this was not sufficient, the island was to suffer further when a manned lighthouse station was established in 1889. Domestic stock contributed to the depletion of vegetation, and cats, destined soon to become wild, made their mark on bird populations. The North Island saddleback, plentiful in 1878, soon vanished, the tui, tit, and parakeet, recorded earlier this century, are now absent, and the number of

grey-faced petrels breeding on the island has declined.

Nevertheless, despite these depredations, Cuvier retained some of its more distinctive features. It has remained mercifully free from European rats, tuatara are present, rare native trees such as tawapou, parapara or birdcatching tree, and broad-leaved maire are plentiful, and Maori cucumber is also to be found. There is, in addition, an interesting invertebrate fauna which includes endemic snails. After a visit by L. C. Bell, of the Wildlife Branch, in 1953, the island was purchased by the Crown with a grant from the Departments of Lands and Survey and Internal Affairs in 1956. In 1957 it was declared a reserve for the preservation of flora and fauna, and today it is administered by the newly formed Hauraki Gulf Maritime Park Board. Once it had been established that Cuvier Island was not beyond redemption and in fact was ideally suited as a site for testing management techniques before applying them to larger islands, and where rare or threatened fauna might be introduced for conservation and study purposes, then came the task of planning its rehabilitation.

Goats Exterminated The far-reaching consequences attached to the deterioration of vegetation made the removal of the worst offenders — the goats — an immediate priority. After a preliminary survey in 1959 during which 160 goats were destroyed, a team of four hunters spent a month on the island in June 1960 and shot a further 333 animals. A year later the extermination was complete when three which had managed to evade the hunters were destroyed together with their four kids.

The next logical step was to control the domestic stock from the lighthouse station, as the lighthouse reserve boundary fence had long fallen into disrepair. Two wildlife officers were sent to the island for a month in June 1963 and a new fence was erected across an isthmus. Surplus sheep and cattle were disposed of, and there have been no domestic animals on the reserve since then. As a result, bush species are regenerating spectacularly, and though regrowth on the exposed coastal faces is understandably slower, the menace of erosion has been almost completely halted.

Controlling feral cats on important bird islands has always been a problem for both ecologists and management staff, and the situation on Cuvier Island was no exception.

Four visits were made between 1960 and 1964 during which time the entire population of 12 animals was trapped and destroyed; subsequent searches by wildlife officers have failed to find any evidence of wild cats on the island.

Allied to the problem of feral cat removal was similar control of the domestic cats. Keepers were reluctant to part with their pets, and the last domestic cat was not removed until 1970. Instructions have now been issued by the Marine Department prohibiting the taking of these animals to the island.

With cats no longer a problem and forest regeneration progressing satisfactorily, the way was clear to reintroduce the rare North Island saddleback, recently confined to Hen Island in the Hen and Chickens Group. On 25 January 1968, 29 birds were released on Cuvier Island and these have thrived to the extent that the species is now plentiful in wooded areas.

Cuvier Island is a single example of what can be, and is being, accomplished in New Zealand in conserving or re-establishing native plants and animals. It represents the type of Cinderella story which could be repeated on a great and growing number of other islands urgently needing attention, if it were not for the restrictions imposed by limitations of staff numbers and finance.