THE BIRDS OF PONU (CHAMBERLIN'SI ISLAND) , HAURAKI GULF … The... · 2013. 11. 3. · anticipated—the sighting of North Islan Kaka mad y be indicative of this. A further surve

T A N E 25, 1979

T H E BIRDS OF PONUI (CHAMBERLIN'S) ISLAND, HAURAKI GULF, AUGUST 1978

by P . J . Bellingham Department of Botany, University of Auckland. Private Bag, Auckland

S U M M A R Y

Thirty-three species of birds were sighted on or near Ponui Island during a visit in August, 1978. Of these, ten species are sea birds and twenty three species are land birds (one being domestic in origin). Five species previously recorded (McKenzie 1972, 1976) were not sighted.

I N T R O D U C T I O N

During the Auckland University Field Club scientific trip to Ponui Island in late August, 1978, a survey of bird life was undertaken.

Ponui Island is situated in the Hauraki Gulf and is the most eastern of the Inner Gulf islands (Brown 1979, Fig. 1). The island has been farmed since the 1850\s and about two thirds of the islands 1770 hectares is clothed in introduced grasses which form open pasture. A range of other habitats are also represented and these include teatree (Leptospermum) scrub, raupo marsh (Typha orientalis) and remnants of broadleaf and kauri (Agathis australis) forest. The kauri forest was milled in the early 1900's; the remain-ing forest is periodically grazed (during bad winters) but otherwise is undis-turbed. Most of the other areas have been continuously grazed and regeneration is limited, to the extend that breeding by land birds may be impeded. With the exception of rats, stoats and wild cats, there are no predators on Ponui Island.

The North Island Kiwi (Apteryx australis mantelli) has been introduced to the island (OSNZ 1970, E . Chamberlin pers. comm.) but was not seen during this survey, although one may have been heard at dusk near the Trig Station. There are indications that the kiwis may now be breeding (McKen-zie 1976).

M E T H O D S

A l l birds seen were noted, while an attempt was made to cover as much of the island as possible, and assess each of the various habitats. Bird numbers are recorded only for comparatively uncommon species, in other cases an estimate of relative abundance has been made. Identification follows Falla et al. 1966 and nomenclature is in accordance with the "Annotated Checklist" (OSNZ 1970).

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O B S E R V A T I O N S

Australian Gannet, Sulci bassana senator. One seen in the sea off Kauri Point.

Pied Shag, Phalacrocorax varius varius. Common around coast. A large colony of about 60 birds was seen in two large pohutukawa trees (Metrosideros excelsa) at Third Bay, on the east coast of the island.

Little Shag, Phalacrocorax melunoleucos brevirostris. A solitary bird seen at Scully Reef at the north-east end of the island, roosting on a rocky outcrop.

White-faced Heron, Ardea novaehollandiae. Occasional in shallow bays around the island.

Grey Duck, Anas superciliosa superciliosa. Two seen flying overhead at Green Bay.

Harrier, Circus approximans gouldi. Common over bush and farmland. Brown Quail, Synoicus ypsilophorus. Two seen in a field near the summit

of the island. Peafowl, Pavo cristatus. A few introduced by the Chamberlin family have

a free run of the homestead area. Variable Oystercatcher, Haematopus unicolor. Four birds seen, each of the

black form—one pair at Scully Reef, and two birds on mudflats at Oranga Bay.

New Zealand Dotterel, Charadrius obscurus. Three birds seen on a sandy beach east of Chamberlin's Bay at the north of the island, and a further three birds seen at stream mouth at Galatea Bay.

Pied Stilt, Himantopus himantopus leucocephalus. Occasional on mudflats around the island and in marshy farmland.

Black-backed Gul l , Larus dominicanus. Common around the coast. Red-Billed Gul l , Larus novaehollandiae scopulinus. Common around the

coast. Caspian Tern, Hydroprogne caspia. Two birds seen fishing off Scully Reef,

and three birds roosting on a rocky outcrop on the reef. White-fronted Tern, Sterna striata. Commonly seen fishing off the coast all

around the island, and nine birds seen roosting at First Bay, at the south of the island.

New Zealand Pigeon, Hemiphaga novaeseelandiae novaeseelandiae. Up to nine birds seen feeding daily in a large Japanese Elm at the homestead, Poroaki Bay. Otherwise, occasional through coastal and kauri forest.

Morepork, Ninox novaeseelandiae novaeseelandiae. One seen at dusk in coastal forest near Poroaki Bay.

New Zealand Kingfisher, Halycon sancta vagans. Common around the coast, fishing or roosting in pohutukawa trees.

Skylark, Alauda arvensis arvensis. Singly or in small flocks over farmland over the whole island.

Welcome Swallow, Hirundo tahitica neoxena. Several seen hawking insects

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over marshy areas and around the coast, and seen in small flocks over farmland throughout.

New Zealand Pipit, Anthus novaeseelandiae novaeseelandiae. Single birds throughout farmland and open scrub.

Grey Warbler, Gerygone igata igata. Common in teatree scrub east of the summit, and through kauri forest; less common in coastal forest.

North Island Fantail, Rhipidura fuliginosa placabilis. Common throughout all forest and scrub.

Blackbird, Turdus merula merula. Common through all forest and scrub and in all farmed areas.

Silvereye, Zosterops lateralis lateralis. Small flocks common throughout all scrub and forest.

Tui , Prosthemadera novaeseelandiae novaeseelandiae. Up to seven birds feeding on puriri flowers (Vitex lucens) in a large tree at Poroaki Bay. Otherwise occasional through coastal and kauri forest.

Yellow-hammer, Emberiza citrine/la sylvestris. Occasional small flocks over farmland and Leptospermum scrub.

Chaffinch, Fringilla coelebs gengleri. Common over all farmland. Greenfinch, Carduelis chloris chloris. Occasional over farmland, and a few

seen in Leptospermum scrub. House Sparrow, Passer domesticus domesticus. A few seen around the

Poroaki Bay homestead, and at Motunau Bay at the south of the island. Starling, Sturnus vulgaris vulgaris. Occasional small flocks over farmland. Indian Myna, Acridotheres tristis. Common over farmland, scrub and

coastal forest. White-backed Magpie, Gymnorhina tibicen hypoleuca. Occasional

throughout farmed areas.

DISCUSSION

The terrestrial bird life of Ponui Island is dominated by introduced species, as might be anticipated in view of the modified nature of the greater proportion of the island. Apart from welcome swallow, pipit and harrier, the birds of open farmland were all exotic.

The teatree scrub provides an overlap habitat between the farmland, favoured by exotic species, and the forest habitats, favoured by native species. Consequently this habitat provides an even mixture of both native and exotic species. The native species typically include those that adjust most readily to disturbed habitats (fantail, grey warbler, morepork and kingfisher), while many of the exotic birds are also found on open farmland, e.g. finch species.

With the exception of blackbird and myna, introduced birds were not recorded in forest habitats. The coastal and kauri forests both support sizeable numbers of tui and native pigeon, while the smaller bush birds were confined almost exclusively to the kauri forest. The lack of smaller bush

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birds in coastal forest is probably due to the browsing by stock which has seriously modified the understorey (Brown 1979a). North Island Kaka (Nestor meridionalis septentrionalis) has been reported from the kauri forest (McKenzie 1972), but no sign was seen in this survey. Shining Cuckoo (Chalcites lucidus lucidus) has also been reported (McKenzie 1972), but was not recorded in this survey. This absence is the result of migrational pat-terns and probably does not represent a 'real' absence. The introduced Kiwis may favour the forested areas.

Freshwater habitats are noticeably lacking; the few streams are not large enough to support permanent populations of ducks. The main freshwater habitats are stretches of marsh and swamp. In these were recorded Pied Stilt, and Welcome Swallow were observed hawking insects above. A long stretch of swamp extends from the centre of the north end of the island to its outlet at Galatea Bay, north of Oranga Bay; an area which would perhaps be suitable for waterfowl to breed. This swamp was investigated for Spotless Crake (Porzana tabuensis plumbed), reported from Ponui Island from a 'long narrow swamp' (McKenzie 1972), but the bird was neither seen nor heard. Another swamp that emerges at Motunau Bay in the south was not thoroughly investigated.

Many of the common coastal birds of the inner Gulf area e.g. Gannet, Caspian and White-fronted terns, Pied Shag, Black-backed and Red-billed Gulls, were all seen flying close to the island. Scully Reef at the north-east corner of the island provides a roost for many species, including two sightings of both New Zealand Dotterel—on shellbanks—and of Variable Oystercatcher. Presumably the list of species would be augmented in sum-mer months by internal migrants and trans-equatorial migrants, as there is no apparent shortage of suitable mudflats, especially on the more sheltered southern and western coasts.

Although there are no opossums (Trichosurus vulpecula Kerr) on Ponui Island there are rats (Rattus sp.), stoats (Mustela erminea Linn.) and a few wild cats (Felis catus Linn.). No estimates of numbers were made but these introduced predators probably have an adverse effect on bird numbers.

Assessment of bird populations at this stage of the year would probably tend toward underestimation due to relatively less activity by many birds during the winter months. In summer months there may, therefore, be fur-ther additions to this species list, as well as the addition of migratory species. A summer survey may also relocate the Spotless Crake. Should the present regeneration of kauri forest be allowed to continue without disturb-ance, an increase in both numbers and species of bush birds might be anticipated—the sighting of North Island Kaka may be indicative of this. A further survey would be useful to assess the present status of the introduced Kiwi population.

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

I wish to thank the Chamberlin family of Poroaki Bay for making this study possible and for accommodation for the duration of the study; Miss E. Brown and Mr C. Turnbull who assisted in field observations; and Miss E. Brown for reading this manuscript and suggesting improvements.

REFERENCES

Brown, E .A . 1979: Auckland University Field Club Scientific Camp to Ponui Island, August 1978. Introduction and Acknowledgements. Tune 25: (this issue).

Brown, E.A. 1979a: Flora and vegetation of Ponui Island, Hauraki Gulf, New Zealand. Tane 25: (this issue).

Falla. R.A., Sibson, R.B. & Turbott, E .G. 1966: A field guide to the birds of New Zealand and Outlying Islands. 2nd Edn. Collins, London. 254p.

McKenzie, H.R. 1972: In search of birds in New Zealand. Reed, Wellington. 256p. McKenzie, H.R. 1976: Brown kiwi (Apteryx australis), p.247 In: Edgar, A .T . 1977: Classified

summarized notes. Notornis 24: 246-279. OSNZ 1970: Annotated checklist of the birds of New Zealand. Ornithological Society of New

Zealand Incorporated. A . H . & A.W. Reed, Wellington. 99p.

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