T A N E 23, 1977

T H E BIRDS O F T H E M O T U R O A I S L A N D S

by G.P. Farley Clarks Beach Road, Waiau Pa

S U M M A R Y

Thirty species of birds were sighted on or near the islands in the Moturoa Group during a visit in May, 1976. Two species previously recorded (Adams 1968) were not sighted, while eight new records were made. A total of thirty-two species of birds are recorded for the Moturoa Island Group.

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

The Moturoa Island Group consists of four small islands and several rocky stacks centred on latitude 3 4 ° 4 7 ' S and longitude 173°22 'E . For a full description of the islands, see Wright (1977a).

During the Auckland University Field Club scientific trip to the islands (8-16 May, 1976) the largest island in the group, Whale Island, was surveyed extensively while shorter visits were made to Green, Sugarloaf and Moturoa islands and the nearby mainland. The birds recorded were identified by their song or by sight (with the aid of binoculars). During night surveys (made to identify incoming pelagic species) voice and capture were used for identification. The ordering and nomenclature used follows Falla et al. (1970). Distribution and abundance o f the birds is shown in Table 1.

SPECIES LIST

Blue penguin Eudyptula minor This species was very numerous on the outer three islands where the petrel

scrub (Wright 1977b) was easily penetrated by the birds. Whale Island, with its modified vegetation, supported smaller numbers which stayed near the coast.

Diving petrel Pelecanoides urinative Although it was their non-breeding season, small numbers (3-6) came ashore

nightly at Commodore Bay, Whale Island. Larger numbers were recorded on the outer three islands (where the diving petrel is recorded as an abundant breeder -Adams 1968).

Fluttering shearwater Puffinus gavia Flocks of twenty or more birds passed within one kilometre of the islands.

None were present ashore as this was their non-breeding season.

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Grey faced petrel Pterodroma macroptera Moderate numbers (about 20) were found on Whale Island. However, larger

populations occurred on the outer three islands. Much courtship and burrow cleaning was in progress although no eggs were found.

All ied (little) shearwater Puffinus assimilis haurakiensis This bird was scarce on all the islands, especially Whale Island where only one

or two birds were heard arriving.

Giant petrel Macronectes giganteus A lone bird was sighted off Whale Island, 1.5km towards Cape Karikari .

Red billed gull Larus scopulinus Although only three to six visited the islands, large flocks were seen feeding

1 km out to sea.

Southern black backed gull Lams domenicanus Several birds were seen around all the islands.

Reef heron Egretta sacra A pair, which were based on Moturoa Island, visited all the islands regularly in

the course of feeding.

White fronted tern Sterna striata Flocks in excess o f 200 birds were seen feeding about 1km out to sea. Large

numbers were seen roosting on rocks off Cape Karikari .

Gannet Sula senator Several birds were seen passing daily.

Pied shag Phalacrocorax varius Single birds were frequently seen fishing in the vicinity o f the islands. They

came from a colony of about 50 birds based on the mainland. Up to 15 were seen resting on rocks off Cape Karikari .

Little shag Phalacrocorax melanoleuros brevirostris A lone bird was seen off Cape Karikari .

Caspian tern Hydroprogne caspia Three to six were seen about 1km out to sea.

Kingfisher Halcyon sancta Four or five birds were seen on all islands. On Whale Island, a family of three

operated from the only sizeable tree on the island, a lone stunted pohutukawa (Metrosideros excelsa) on a rock stack.

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Welcome swallow Hirundo neoxena Several were seen to pass over all islands.

Harrier Circus approximans gouldi A pair regularly hunted over the islands.

Silvereye Zosterops lateralis Small flocks o f no more than six birds were seen on each island.

Australian brown quail Synoicus ypsilophorus Small numbers were sighted on a grassy portion o f Whale Island and on an

adjoining rock stack.

Pipit Anthus novaeseelandiae Two were seen on Whale Island. (On the mainland, skylarks far outnumbered

pipits despite the area being rough pasture land.)

Fantail Rhipidura fuliginosa A lone bird was seen during a short visit to Moturoa Island. Other members of

the party reported 3 or 4 birds in the Hymenanthera scrub on the summit of Moturoa Island.

Starling Sturnus vulgaris Large numbers (in excess of 100) roosted on all the islands. On Whale Island,

it was noted that all areas of petrel scrub were utilised. Only a few birds remained during the hours of daylight.

Hedge sparrow Prunella modularis This species was abundant on the outer three islands where it showed a

marked preference for petrel scrub. Few were sighted on Whale Island.

Myna Acridotheres tristis Large numbers visited the islands daily during fine weather with approxi­

mately 1 5 birds stopping at each island.

Blackbird Turdus merula Small numbers (4-5) were present on the outer islands but they were more

common on Whale Island.

Greenfinch Chloris chloris About six birds were present on Whale Island. Only one or two were seen on

the other 3 islands.

Goldfinch Carduelis carduelis Birds were occasionally heard overhead. On Whale Island, a flock of about 20

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Table 1: The Distribution and Abundance of avian species recorded on the Moturoa Islands, 8-16 May, 1977. A = abundant (>20); C = common (3 - 20); S = scarce (<3); *= new record for the Moturoa Island Group.

Species Whale Sugarloaf Green Moturoa At Sea Island Island Island Island Island

Blue penguin C A A A A Diving petrel s c C c c Muttering shearwater - - - - A Grey faced petrel c A A A -Allied shearwater s S S S S Giant petrel* - - - - s Red billed gull c c C c A Southern black backed gull c (' C c -Reef heron c (' C c -White fronted tern - - - - A Gannet - - - - c Pied shag - - - - c Little shag* - - - - s Caspian tern - - - - s Kingfisher* c c c c -Welcome swallow (' c c c -Harrier c c c c -Silvereye c c c c -Australian brown quail c - - - -Pipit s - - - -Fantail - - - s -Starling ( A A A -Hedge sparrow* s A A A -Myna* c C (' c -Blackbird c (' c C -Greenfinch c s s s -Goldfinch c s s s -House sparrow - s s s -Skylark* c - s - -

Thrush* - - - s -

birds was sighted. When disturbed they flew to the mainland.

House sparrow Passer domesticus None were sighted on Whale Island and only one or two were seen on the

outer islands.

Skylark Alauda arvensis Although common on the mainland, only three birds were seen on Whale

Island while a lone bird was recorded on Green Island.

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Thrush Turdus philomelos One bird was seen on Moturoa Island.

Two birds previously recorded for the islands were not sighted during the present survey. The white-faced storm petrel (Pelagodroma marina maoriana), a summer breeder, migrates from the New Zealand region during winter so sightings could not be expected. The variable oystercatcher (Haematopus reischeki) is a largely sedentary bird and the previous records may have been visitors from the mainland.

Only rough estimates of numbers of the pelagic species present on the islands can be made. Burrows were extremely numerous on the outer islands and there was evidence of considerable amounts of activity. It is estimated that there could have been as many as 600 grey-faced petrels returning to Moturoa Island at dusk.

DISCUSSION

Pelagic species apart, the Moturoa Island Group has a very sparse resident avifauna. Pelagic species such as the petrels were more common on the outer islands (Green, Sugarloaf and Moturoa) where avian burrows were extremely frequent. Species such as the red billed gull, southern black backed gull and reef heron, which possibly nest in the group, were common on all the islands. Other birds such as the white fronted tern, pied shag and little shag which would find the limited habitats available unsuitable for breeding were not sighted on any of the islands. Many individuals sighted were probably visitors from the mainland, e.g. silvereyes appeared to be part o f a winter feeding flock. Of the introduced species present, the more aggressive offshore island colonisers such as the hedge sparrow, starling and blackbird were abundant on many of the islands. Other introduced species, e.g. myna, greenfinch and goldfinch appeared to be daily visitors to the islands.

The relatively low bird population found on the islands was largely due to natural factors such as their ruggedness and restricted vegetation. The steep rocky faces and stony beaches provided unsuitable breeding grounds for most species. Whale Island apart, the islands were devoid of any freshwater, even seepages. The vegetation on the outer islands was mainly dense petrel scrub -dominated by taupata (Coprosma repens) and Hymenanthera novae-zelandiae. Together with the disturbance made by breeding pelagic birds the low canopy makes the habitat unsuitable or marginal for many species e.g. the thrush, fantail and pipit.

The season probably also affected bird numbers obtained, especially those o f summer breeding pelagic species.

Whale Island has been extensively modified by cultivation (Wright 1977b). Except for pockets, all petrel scrub has been destroyed leaving a more open covering o f flax (Phormium tenax), cabbage trees (Cordyline australis) and grasses (Zoysia, Poa and Stenotaphrum spp.) wi th patches of mingimingi (Cyathodes fasciculata), manuka (Leptospermum scoparium) and bracken

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(Pteridium aquilinium var. esculentum). This has reduced the numbers of pelagic birds breeding and roosting on the island.

The islands are extremely important as breeding grounds for the pelagic species recorded, not only because of their remoteness, but also because of their inaccessibility which has meant the islands have remained free of vermin, particularly rats {Rattus spp.).

Since the last survey, introduced birds appear to have extended their ranges to include the islands. The introduced bird population may well continue to increase in the next few years.

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

The author would like to thank all Field Club members who contributed observations and Dr P .F . Jenkins for critically reading the manuscript.

R E F E R E N C E S

Adams, G .P . 1971: Wildlife Survey of the Moturoa Islands. Notornis 18: 43-49. Falla, R . A . ; Sibson, R . B . & Turbott, E . G . 1970: A Fie ld Guide to the Birds of New Zealand.

2nd Edit ion. Collins. Wright, A . E . 1977a: Auckland University Fie ld Club scientific trip to Moturoa Island Group

- Introduction and Acknowledgements. Tane 23 (this issue). Wright, A . E . 1977b: Flora and Vegetation of the Moturoa Island Group, Northland. Tane

23 (this issue).

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