T A N E 28, 1982

O F F S H O R E I S L A N D S R E S E A R C H G R O U P T R I P TO R A K I T U (ARID) I S L A N D , N O R T H - E A S T N E W Z E A L A N D ,

N E W Y E A R 1980-1981 Introduction and Acknowledgements

by Bruce W. Hayward N . Z . Geological Survey, P .O. B o x 30368, Lower H u t t

INTRODUCTION

Rakitu (or Arid) Island (latitude 36°06'S, 175°30'E) lies off the east coast of Great Barrier Island, north-east New Zealand (Fig. 1). It is situated 5.5 km due east of Whangapoua Beach, although the nearest point on Great Barrier Island (Whangawahia Bay) is only 2.5 km to the south.

Rakitu is roughly oval in o u t l i n e , 2.75 km long and 1.75 km wide and covers approximately 350 hectares. It is surrounded almost completely by steep, rocky, partly vegetated cliffs that rise up to heights of nearly 180 m in places (Fig. 2). These cliffs are breached in the north-west by a narrow embayment (200 m wide, 400 m long) known as Arid Cove (Fig. 3). The Cove provides a sheltered anchorage except in stormy weather from the north-west, and is also the only really suitable landing spot.

Apart from a small beach on the north side of Ora Point, the only sandy beach on the island is a 200 m long strip at the head of Ar id Cove (Fig. 3). Boulder beaches are present at the foot of cliffs around other parts of the island but are unsuitable for landing except in calm conditions.

Rakitu Island is divided into two high-standing blocks by the central valley of Abbott's Stream (Fig. 1). Both blocks are roughly equal in size, rising to about 200 m A.S.L. , and have numerous rocky bluffs around their summit ridges (north-east block) or plateau (south-west block). Each block is drained by tributaries of Abbott's Stream on the landward side, and is bounded by steep coastal cliffs on the seaward side.

Open grassland covers approximately half the island, particularly the floor and lower slopes of Abbott's Stream valley and hills above Ar id Cove (Fig. 4). Kanuka and mixed coastal forest in the central part of the island is mostly confined to the incised valleys of Reserve, Maori and Bush Creeks. Further pockets of coastal forest occur around the steep, seaward-facing slopes and cliffs (Fig. 2). Stock freely graze through most of the forest areas, eating out the young regenerating plants. In areas inaccessible to stock, such as on Te Akau Point, in a fenced off area in Reserve Creek, and in several places on the cliffs, vigorous regeneration is occurring.

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Tokawhero Pt.

Weka Bay

Te pa o Rehua Pt

Kauauennga Pt. Gannet Rock 0

Black and White Rock

Pinnacle Hill

Puketoitoi Pt

<C^y Close Island

Te Akau Pt

F i g . 1. U p p e r Location of R a k i t u (Arid) Is land off the east coast of Great Barr ier Is land, north-east New Zealand. L o w e r M a p of R a k i t u Is land. Names i n ital ics are unoff icial place names taken from old maps, used by the present owner, or coined by our party .

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History It is not known who gave Rakitu its European name of Arid Island,

but presumably it resulted from the barren appearance of its cliffs when viewed by an early visitor. The earliest written description of the island is that of Hutton and Kirk (1868), who spent several hours there in December 1867. They briefly described the geology and botany, and noted that the vegetation (of the open land) had been burnt off only a few days earlier by a party of Maori mutton-birders from Great Barrier Island. The Barrier Maoris reportedly told them that the mutton-birds "used to be very numerous, but that latterly they had become scarce, having been killed off by rats." Ship rats (Rattus rattus) still occur on Rakitu Island.

Hutton and Kirk noted that the rocks were volcanic but erroneously concluded that the central valley system was a former crater. They stated that the name Arid Island was not deserved as "the high, rugged desolate-looking cliffs that encircle the greater part of the island, hide within them beautifully-sheltered valleys, covered with luxuriant fern and bush..."

Rakitu Island was surveyed by the Crown in 1870 and granted to its Maori owners Hone Pama and others in 1871. The map produced shows that even then the areas of forest were limited to only two large patches - around Reserve and Maori Creeks, and around Bush Creek, with a few smaller patches on the cliffs, especially at the south-western end of the island.

Rakitu was sold to Europeans in 1883 and after several changes of ownership was purchased by the Alison family in 1896. When the whaling station at Whangaparapara was operating in the 1940s and early 1950s, men were stationed in two lookout huts on Rakitu (near the trig and above Kauaueringa Point) to watch for migrating whales. In 1951, North Island wekas were introduced and quickly established a thriving population. When the island was purchased from the Alisons in 1956 by the present owner, M r D.B. Rope, it was overrun by 200 wild cattle and had no fences.

The Ropes have greatly improved the quality of the pasture, divided the island into numerous paddocks, cleared some of the second growth bush and fenced off part of the native forest areas. In the late 1950s an attempt was made to build an airstrip on the flat at the head of Abbott's Stream, but this was found to be unsuitable until further work was undertaken early in 1981, after our visit.

Today the island has a resident farm manager and supports 300 cattle and 1 000 sheep.

There has been very little previous work on the natural history of Rakitu Island. After an eighty-five year gap since the observations of Hutton and Kirk (1868), the next recorded visits were in the 1950s and

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Fig. 2. Oblique aerial photograph of the steep, partly vegetated cliffs on the north side of Rakitu Island. "Green Point" is in the foreground, "Reserve Creek" runs down the forested valley in the upper right and "Close Island" lies off the south of Rakitu (upper right corner). Photo: Lloyd Homer, NZ Geological Survey.

Fig. 3. Arid Cove on the north-west corner of Rakitu Island has the only substantial sandy beach on the island and provides a sheltered anchorage and easy landing. Photo: Lloyd Homer.

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1960s by various ornithologists who reported on the birdlife (Bell 1953, Bell and Brathwaite 1964). The most recent work was a three-day survey of the vegetation carried out by Cameron (1980).

The Trip Rakitu Island was chosen for the New Year 1980-1981 expedition by

the Offshore Islands Research Group because little was known of its natural history, and because of its ideal location midway between two groups of better-studied islands - those off eastern Coromandel Peninsula and those off eastern Northland. The island was particularly suited for comparison with Motukawanui (Cavalli Islands) and Urupukapuka (Bay of Islands), two islands of similar size and grazing histories, which were studied by O.I.R.G. in 1979 and 1980 respectively (Fig. 1).

The party of sixteen consisted of Peter Bellingham, Fred Brook, Vivienne Bull , Ewen Cameron, Anne Grace, Roger Grace, Rod Hay, Bruce Hayward, Rod Hitchmough, John McCallum, Peter Matthews, Phil Moore, Murray Potter, L in Roberts, Clare Ward and Anthony Wright. We departed from Leigh and landed in Arid Cove on 30 December 1980. Camp was set up in the stockyards on a small flat knoll 250 metres up the main valley from the beach. A tent where scientific

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Fig. 4. View north across the forested headwaters of Bush Creek to Arid Cove and the distinctive Ladds Knob behind. Most of the lower slopes of the main valley and slopes above Arid Cove are now in pasture.

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work, especially on marine samples, could be carried out during the heat of the day, was pitched at the back of the beach.

The trip was blessed by a remarkable succession of hot, cloudless days, with not a drop of rain, much to the dislike of those with fairer skins. Among the many memorable occasions on the trip were the celebrations, on consecutive evenings, of New Year's Eve and the birthdays of our oldest and youngest members; Rod's organisation of the great weka survey, charades and word games; the inability of botanists to recognise Agathis australis (kauri); and Roger's automatic, hot water shower.

Studies were carried out on the island's rocks, archaeology, vascular plants, lichens, birds, rats, lizards, insects, land snails, spiders and freshwater fauna, as well as the fish, sediments and marine benthic biota in the area of sea around the island, and the results of some of these follow.

The trip concluded with a rather rough but exciting passage back to Leigh on 8 January 1981 and a toast to future O.I.R.G. trips in the local tavern.

A C K N O W L E D G E M E N T S

Our party is extremely grateful to a number of people whose assistance ensured the success of our tr ip . In particular, we would l ike to thank M r B r y c e Rope, his family and farm manager, for permission to stay on his land and carry out work on the natural history of the island. Their friendly hospitality and the use of their freezer made our stay a memorable one. W e are also grateful to M r Bruce M c G h i e for the use of his boat as a bunkhouse at L e i g h on the night before we left and for transport ing us to and from R a k i t u .

W e also thank the A u c k l a n d Univers i ty F ie ld Club , A . H . I . Minera l s L t d , Entomology D iv i s i on - D S I R , and M a d o Underwater Club for the loan of camping equipment. M r B u l l k indly donated several geese and some lamb which was heartily devoured and M r s W r i g h t cooked and froze much of the other meat.

R E F E R E N C E S

Be l l , L . C . 1953: A r i d Island. Unpubl ished Report, Department of Internal Af fa i rs , Wel l ington.

B e l l , B . D . & Brathwaite , D . H . 1964: The birds of Great Barr ier and A r i d Islands. Notornis 10:363-382.

Cameron, E . K . 1980: P lant life of R a k i t u (Arid) Island. Unpubl i shed Report , Department of Lands and Survey, A u c k l a n d .

H u t t o n , F . W . & K i r k , T. 1868: Description of A r i d Island, H a u r a k i Gul f . Transactions and Proceedings of the New Zealand Institute 1:108-112.

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