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

by Susan M . Fogarty* and M . E . Douglasf

P A R T 1: A B U N D A N C E OF L A N D B I R D S

S U M M A R Y

A species list and abundance of the birds of Red Mercury Island was com-piled in August, 1971, along with observations on foraging in saddlebacks.

36 species are recorded, of which 17 are landbirds. Of these, fantails, grey-warblers, bellbirds and saddlebacks are the most abundant.

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

From August 21-28 a survey of abundance of landbirds on Red Mercury Island was made. Previous surveys have been made in 1961 (Edgar, 1962) and 1962 (Skegg, 1963). Adams (1969) and Blackburn (1970) have made brief visits to the island to establish the success of North Island saddleback, released there in 1966.

M E T H O D

For convenience the island was divided into four more or less equal areas. Area 1 lay north west of a straight line drawn from the camp (grid reference 418878) to 155 metre spot height (510 ft.). Area 2 was bounded by a line from grid reference 423884 to 155 metre spot height to the north east, and grid reference 423884 to V o n Luckner's Cove to the south east. Area 3 covered the promontory in the south east. Area 4 was the remainder of the island north of the southern coast.

The area around Rolypoly Bay and Lunch Bay was covered adequately, but due to a lack of time, the northern and eastern sectors were less fully covered.

When making abundance counts the observer walked slowly more or less directly through the area. Stops were made for intervals of approximately three minutes after every ten minutes of walking. Individual birds seen and heard were recorded.

R E S U L T S

The results of the survey are presented in Table 1. The figures represent counts over every ten minutes walking and for each three minute stop. Average and maximum numbers are given for each area and for the island as a whole.

•Department of Geography, University of Auckland

f Department of Zoology, University of Auckland

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Table I: Counts of birds seen and heard for each 13 minute walk/stop interval on Red Mercury Island.

A R E A 1 A R E A 2 A R E A 3 A R E A 4 T O T A L

No. of Surveys 2 2 1 2

Av Mx Av Mx Av Mx Av Mx Av M \ Harrier 1.5 3 1.5 3

Red-crowned 12.5 13 5.0 6 2.0 2 5.0 6 24.5 2 7 parakeet

Morepork 1.0 1 0.5 1 1.5 2

Skylark 0.5 1 0.5 1

Grey warbler 34.5 35 13.0 17 12.0 12 15.5 19 75.0 83

Fantail 37.5 40 17.0 22 12.0 12 10.0 11 76.5 85

Blackbird 5.0 8 3.5 5 3.0 3 1.0 2 12.5 13

Silvereye 6.0 7 3.5 7 9.0 11 18.5 25

Bellbird 29.0 33 11 5 12 12.0 12 17.5 20 60.0 77

Chaffinch 2.0 3 1.0 1 3.0 4

Saddleback 11.5 13 6.5 9 8.0 8 17.0 24 41.0 54

DISCUSSION

Undercounting for some species was inevitable due to a number of reasons: The noise created when moving through thick scrub tends to make

secretive species more wary and they may not be counted; on the other hand, birds such as saddlebacks and blackbirds may give alarm calls due to disturbance while fantails are attracted by disturbance. The canopy usually prevented birds in flight being seen. On some surveys, probably because of the wind and rain, the number of birds recorded were considerably lower than expected. The maximum figures would therefore tend to be the most realistic, although less so for the flocking and calling species.

Possible duplication in counts of individual birds was mainly avoided by the more or less direct route taken. Different routes through the same area were considered as separate surveys.

Species such as starling and kingfisher have not been included in the abundance count due to their frequenting coastal cliffs which were often inaccessible. Mention has however, been made of them in the species list.

A l l twenty-nine saddlebacks liberated by the Wildlife Service on 30 January, 1966 had been banded. The number recorded during our 1971 visit (a maximum of 54) indicates that breeding by the species has been successful. Only one banded bird was seen, suggesting the other birds seen had been reared on the island, since saddlebacks are unable to fly more than 50 metres at a time.

The abundance of saddleback was greatest in areas 1 and 2. Although Adams (1969) suggested that their distribution was governed by stands of large pohutukawa (Metrosideros excelsa),v/e found that birds were distributed through-out the regenerating vegetation including low lying flax, bracken, tea-tree and

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dense coastal Coprosma. Blackburn (1970) also found them in similar scrub conditions.

Fantails, grey warblers, bellbirds and saddlebacks are the most numerous and widely distributed birds. Red-crowned parakeets and silvereyes are locally abundant. The other species are relatively uncommon.

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

P A R T II: SPECIES LIST

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

A list of species recorded from 21-28 August, 1971, on Red Mercury Island and at sea between Red Mercury and Whitianga (21,28 August) is presented. Previous recordings have also been included in some cases.

Nineteen of the 36 species recorded are seabirds; the remainder are landbirds.

A N N O T A T E D SPECIES LIST

Eudyptula minor (little blue penguin) One at sea between Whitianga and Red Mercury on 21 August. Eight dead

along Rolypoly Bay. Burrows found at Rolypoly Bay and birds seen coming ashore at night. Edgar (1962) records them as breeding also at Lunch Bay.

Macronectes giganteus (giant petrel) Ten at sea between Whitianga and Red Mercury on 21 August. Small numbers

observed off the coast.

Daption capensis (cape pigeon) Edgar (1962) records one bird off Red Mercury.

Pterodroma macroptera (grey-faced petrel) Large numbers at sea between Red Mercury and Opito Point on 28 August.

Burrows found on slopes and ridge tops around the perimeter of the island, including some containing eggs or chicks up to one week old. Two birds were banded as adults in September 1961 by Skegg and Bell (Banding records Wild-life Service).

Pterodroma inexpectata (mottled petrel) Specimen picked up dead on the beach in the 1920's (Falla, 1934).

Pterodroma pycrofti (PycrofVs petrel) Skegg (1963) records breeding at Rolypoly Bay and Lunch Bay.

Puffinus carneipes (flesh-footed shearwater) Two at sea between Whitianga and Red Mercury on 21 August.

Falla (1934) records them as breeding on Red Mercury.

Puffinus bulleri (Buller's shearwater) Three at sea between Whitianga and Red Mercury on 21 August.

1 ! 1

Puffinus gavia (fluttering shearwater) Nineteen at sea between Whitianga and Red Mercury on 21 August. Small

numbers of birds came ashore at Rolypoly Bay. One specimen picked up dead from Rolypoly Bay.

Puffinus assimilis (allied shearwater) Small numbers seen at Rolypoly Bay.Skegg (1963) reports them breeding

there.

Pelagodroma marina (white-faced storm petrel) None seen on either crossing, but Edgar (1962) noted up to 100 birds.

Pelecanoides urinatrix (northern diving petrel) At dusk on 21 August, 160 seen between one and two miles offshore.

Possibly breeding in small numbers on Red Mercury.

Sula bassana (Australian gannet) Small numbers seen offshore all around the island. Thirteen off Rolypoly

Bay on 22 August.

Phalacrocorax carbo (black shag) One seen between Whitianga and Red Mercury on 21 August.

Phalacrocorax varius (pied shag) Three between Whitianga and Red Mercury on 21 August. Eight occupied

nests and 24 birds in a pohutukawa at northern Rolypoly Bay.

Circus approximans (harrier) Three individuals seen. The courtship display of one pair was observed. Skegg

(1963) reported movement of this species from island to island. May breed.

Larus dominicanus (black-backed gull) Forty at sea between Whitianga and Red Mercury on 21 August. Fifty roosting

on rock stack southwest of Red Mercury. Thirty-three off Rolypoly Bay on 22 August. Edgar (1962) recorded up to 200 offshore.

Larus novaehollandiae(red-billed gull) Large numbers at sea between Whitianga and Red Mercury.

Sterna striata (white-fronted tern) Ninety at sea between Whitianga and Red Mercury on 21 August.

Cyanoramphus novaezelandiae (red-crowned parakeet) Found mainly in coastal pohutukawa groves. Breeding.

Chalcites lucidus (shining cuckoo) Skegg (1963) records this species calling in November.

Ninox novaeseelandiae (morepork) Heard calling at night. One sighted at 1330 hours sitting on a branch in bush

above V o n Luckner's Cove.

Halycon sancta (kingfisher) Present in small numbers around the coastline, generally sitting on logs among

the boulders.

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Alauda arvensis (skylark) One seen hovering above the grassy flat between Lunch Bay and Rolypoly

Bay. Not previously recorded.

Anthus novaeseelandiae (New Zealand pipit) Skegg (1962) records one from Lunch Bay.

Prunella modularis (hedge sparrow) Edgar (1961) and Skegg (1962) record this species from Red Mercury.

Gerygone igata (grey warbler) Abundant in all habitats throughout the island.

Rhipidura fuliginosa (fantail) Probably the most common bird on the island in all habitats.

Tardus merula (blackbird) Found in small numbers in more open bush.

Zosterops lateralis (silvereye) Small (locks found in inland scrub and among Coprosma repens (Taupata)

along the shore. One flock was observed feeding on green Taupata drupes.

Anthornis melanura (bellbird) The third most common bird on the island especially abundant in coastal

pohutukawa.

Prosthemadera novaeseelandiae (tui) Edgar (1962) suggests these birds probably visit the island when pohutukawa

is in bloom.

Fringilla coelebs (chaffinch) Present in small numbers.

Sturnus vulgaris (starling) Small flocks seen flying around northern cliff faces. Skegg (1963) reports

much inter-island movement.

Philesturnus carunculatus rufusater (North Island saddleback) Released in January 1966. At least 54 were recorded. There are probably

more birds along the northern and eastern coasts than were recorded due to wet and windy weather on the days these areas were covered. The central eastern area was also poorly covered.

C O N C L U S I O N

Thirty-six species were recorded from Red Mercury. Of the 19 species of seabirds, five were found to definitely breed on the island, and another three possibly do so. Twelve of the 17 species of landbirds almost certainly breed, and another three possibly do so. Two species are visitors.

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

PART III: SADDLEBACK FEEDING STATIONS IN AUGUST

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

The North Island saddleback (Philesturnus carunculatus rufusater) was re-leased on Red Mercury Island in 1966. The large number of birds successfully reared on (his island since the original liberation, appears to support the con-tention of D.S.I.R., Wildlife Service and O.S.N.Z. , that suitable feeding sites may be the most important single factor determining the success of liberation. Twenty-nine banded birds were liberated, and only one of these originals was seen in our 1971 visit out of a maximum total of 54 birds recorded. At least 30 of the birds seen had no bands, indicating that they had been reared on the island. It was impossible to determine whether the remaining 23 birds were banded, as they were not seen clearly, or were only heard.

M E T H O D

Short studies mainly about Rolypoly camp were carried out using a modified form of the methods outlined by Atkinson (1964, 1966), Blackburn (1967), and Merton (1966). Birds were followed, and, at regular intervals of about one minute, the specific foraging station was noted. Reference to vegetation material, height above ground, food material, and feeding method was made in concise notes taken in the field. Because of the rapid foraging movements of the saddleback, a light tape recorder was found useful for note taking in one instance.

The forest was divisible into four storeys: canopy, upper understorey, lower understorey, and ground storey (Atkinson, 1966).

1. Canopy: The uppermost storey of tree crowns unshaded by other crowns.

2. Upper understorey: A storey of plant crowns greater than 2 metres(6ft) and shaded by ttie canopy.

3. Lower understorey: A storey of shrubs, tree ferns etc. from 0.3-2 metres (l-6ft.) in height.

4. Ground storey: The lowermost storey consisting of plants with growing points situated less than 0.3 metres ( l f t . ) above the ground together with the litter.

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R E S U L T S

The results of the feeding stations observations are given in the following tables 1,2 and 3.

T A B L E : 1: N.I. saddleback:- Comparison of feeding stations.

Feeding Stations No. of Observations. Percentage

of Total

Canopy foliage 3 6

Understorey foliage 6 11

Dead foliage 3 6

Flowers, fruit 2 4

Branches, limbs, twigs 23 44

Branch axils, holes, dead branches 7 13

Trunks 3 6

Ground 5 10

52

T A B L E 2: N.I. saddleback:- Time spent in three groups of feeding stations.

Feeding Stations Observations Time in Minutes % of time

Among upper foliage, fruit & flowers

26 37.25 47

Among lower foliage & bark of branches limbs etc. 21 27.00 34

Ground 5 15.50 19

52 79.75

The observations suggest that most of the food collected by saddlebacks probably consists of insect material found in the bark. Larger materials such as Oeceticus omnivorus (bagworm moth) pupae and caterpillars (species unidenti-fied) were also eaten. However birds were also seen extracting nectar or water from the flowers of rangiora (Brachyglottis repanda) and puriri (Vitex lucens), and feeding on fruits of rangiora and karamu (Coprosma robusta.

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T A B L E 3: N.I . saddleback:- Trees and shrubs visited.

No. of Percentage Observations of Total

Metrosideros excelsa (pohutukawa 14 27

Melicytus ramiflorus (mahoe) 1 1 21

Myrsine australis (red matipo) 7 13

Brachyglottis repanda (rangiora) 6 11

Coprosma repens (taupata) 2 4

Coprosma robusta (karamu) 1 2

Vitex lucens (puriri) 2 4

Phormium tenax (N.Z. flax)* 1 2

Solatium sp. 1 2

Leptospermum scoparium (manuka) 2 4

Pteridium esculentum (bracken)* 1 2

(Ground) 4 8

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'Saddleback feeding around bases only.

DISCUSSION

Time did not allow the feeding stations of the saddleback to be studied in great detail. However, whenever a bird was observed, details of feeding methods, levels and stations were recorded.

Saddlebacks generally feed in pairs, and maintain relatively close contact with each other when foraging. On two occasions fantails were seen feeding close-by, probably catching insects disturbed as the saddlebacks probed under bark and moved through the foliage.

Most of the data given in Tables 1-3 was compiled from morning surveys; consequently it could not be ascertained whether different feeding stations were utilized at other times of the day.

Two-thirds of the total ground feeding time was recorded on a single morning following overnight rain. Blackburn (1%7) states that "the abundance of litter is probably a factor contributing to the complete success of transfer on Red Mercury and Whatupuke islands".

Overall an emphasis on branch, limb and twig feeding in the understorey forest can be seen. The data are however inadequate to give more than a general idea of the divison of feeding time in storeys and stations.

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

The authors wish to thank the Wildlife Branch, Department of Internal

Affairs, for making available their unpublished records; all Field Club members

who contributed observations, Mr P.R. Millener for his assistance and Mr P.E.

Jenkins for critically reading the manuscript.

R E F E R E N C E S

Adams. C P . 1969 Unpublished report on saddlebacks from Red Mercury. Wild-life Branch file 12.5.4.

Atkinson, I .A.E. 1964 "feeding Stations and Food of North Island saddleback in August." Notornis 11 (2): 93-7.

1966 "Identification of feeding Stations of Forest Birds in New Zealand." Notornis 13 (1): 12-17.

Blackburn, A . 1967 "Feeding Stations and F'ood of North Island saddleback in November". Notornis 14 (2): 67-70

1970 "Birds of Little Ohena Island". Notornis 17 (4): 297-9. Edgar .A.T. 1962 " A Visit to the Red Mercury Islands" Notornis 10( 1): 1-15.

Falla, R . A . 1934 "Petrels of Northern New Zealand". Rec. Auck. Mus. Inst. 1. (5): 245-59.

Merton, D .V . 1966 'Some observations of Feeding Stations, Food and Behaviour of the N.I . saddleback on Hen Island in January". Notornis 13 ay. 3-6.

Skegg, P .D.G. 1963 "Birds of the Mercury Island Group". Notornis 10 (4): 153-68.