Tone (1970) 16:97-103. 97 NOTES ON THE NORTH ISLAND BREEDING COLONIES OF SPOTTED SHAGS Stictocarbo punctatus punctatus, Sparrman (1786) by P. R. Millener* ABSTRACT The present distribution of the spotted shag in the North Island is outlined from data collected during March April, 1970. These data are compared to those of Stead (1932) and Turbott (1956). INTRODUCTION The spotted shag, Stictocarbo punctatus, is most closely related to the red-footed cormorant S. gaimardi Lesson (1828), of South America (Murphy, 1936). The species has an entirely coastal distribution and breeding colonies are characteristically situated on coastal cliffs with ledges and often overhanging rock faces, or in caves. The spotted shag breeds in the Auckland area (Hauraki Gulf and West Coast), Cook Strait, south-west Nelson, Banks Peninsula, Otago Peninsula and probably on islands off south Westland. The breeding season is relatively long and the breeding peak variable from colony to colony. Generally the Hauraki Gulf colonies are autumn breeding but eggs have been noted at the David Rocks (Noises Islands) in July, August and October as well as in March and April. West Coast birds normally breed in the spring although young chicks have been noted in April at Girdwood Point. The plumage sequences suggested by Murphy (1936) have been adopted in this paper. (Table 1: after Turbott (1956)). TABLE I: Spotted Shag: Adult Plumage. Season Decorative Plumes Crests White Head and Neck Line Plumage is Termed Fig. Pre-nuptial Present Maximum Present PRE-NUPTIAL 2 Egg-laying Rearing of young Usually absent Abraded and partially moulted Present NUPTIAL 3 Absent Lost Obscured POST-NUPTIAL! The most recent account of the distribution and size of the North Island colonies is given by Turbott (1956). Department of Zoology, University of Auckland
FIG. 1: Distribution of Stictocarbo punctatus colonies in the Hauraki Gulf. 1. Otata Island, 2. David Rocks, 3. Te Whau Pt, 4. Anita Bay, 5. Tarakihi Island.
99 THE DISTRIBUTION AND STATE OF COLONIES I. ttauraki Gulf Colonies In 1910 according to Falla (1932) the spotted shag had an extensive distribution in the Hauraki Gulf, but until measures to halt extermination by shooting parties were taken in 1931 all the colonies suffered severely. By 1932 colonies existed only at the David Rocks and Eastern Waiheke Island. Colonies can now be recorded for five areas: (/) Otata (Noises Islands) On the north-eastern coast of the main island of the Noises group a colony comprising one hundred birds was present on 21.3.70. Twenty-four nests were seen, at least sixteen of which contained eggs (including some freshly laid clutches, both complete and incomplete). On a later visit (12.4.70) four nests were seen to contain chicks, ranging in age from perhaps two to ten days. The greatest number of birds previously recorded at this locality was "forty, some on nests" Davenport 2.4.50 (1951). It is of interest that no birds were present on the last recorded visit Turbott, 24.3.56 (1956). (2) David Rocks (Noises Islands) Falla (1932) notes that the tunnel-dwelling colony on the most southerly of the David Rocks "has been for some years past breeding in mid-winter." In late May, 1932, twenty new nests were seen but no eggs were present. Turbott (1956) counted some two hundred birds on 3.3.56 but nesting had not begun, although many birds were assuming pre-nuptial plumage. Twenty-five birds were counted on 22.3.70 and an examination of the interior of the tunnel on 12.4.70 showed seven nests in occupation. Five contained eggs (one of which was just pipping) and another was occupied by two chicks approximately five weeks old. The earliest previous breeding record for the David Rocks was on II. 5.35 as noted by Turbott (1956). There were on this date "three chicks in sparse down" (i.e. less than ten days old). (3) Te Whau Point (Waiheke Island) On the northern coast of Waiheke Island just east of Onetangi, a flourishing colony was noted on 1.3.70. A small island in the bay had on it twenty-five birds, and four nests, all occupied. On the western side of the bay, fifty yards away, one hundred and sixty birds and thirty-nine nests were noted, mostly on the landward side of a large rock. This colony has not been previously recorded.
100 (4) Anita Bay (Eastern Waiheke Island) Throughout the period of Stein's observations, from 1914 until at least the 1950's, a colony was present between Hooks Bay and Anita Bay. The most northerly portion of this colony was noted on 1.3.70 to consist of four groups totalling at least one hundred and fifty birds. Only the southernmost group, occupying an exposed cliff terrace, had nests. There were twelve, all occupied. Some birds may have been nesting in a cave to the north of this terrace but conditions made closer examination impossible. Round the point to the south (almost into Anita Bay) a flourishing colony of one hundred and fifty birds, many in pre-nuptial or nuptial plumage, was noted. There were sixty nests, ten with eggs (including newly laid complete and incomplete clutches). The greatest number of nests recorded previously was fifty-five by T. M. Roberts on 28.12.46 (McKenzie 1948). (5) Tarakihi (Shag Rock) The largest of the early colonies was on Shag Rock which lies a little over two miles to the south-east of the eastern tip of Waiheke Island. According to Stein's observations it consisted, in August, 1914, of four separate groups on the north-east corner of the island and a further group on the north-west corner. An attack in 1919 almost annihilated the colony and by 1930 the island was completely deserted. Intermittent breeding attempts occurred from the mid- 1940's on, but were doubtfully successful until December 1955, when Stein observed about forty nests. On 28.2.70 at least five hundred birds, most in pre-nuptial or nuptial plumage, and some hundred nests were spread over the whole north-east face of the island. Owing to rough seas only a very small area was closely examined. Fifteen nests, five with eggs (some newly laid) were seen. Ponui Island, on which Stein saw ninety birds in nuptial plumage in August, 1949, is reported to be no longer used except as a roost (J. Gaunt pers. comm.). The colony reported by Turbott (1956) to be on Motutakapu Island (off the Coromandel coast, south of Colville), has not been investigated recently.
FIG. 3: Stictocarbo punctatus at Tarakihi Island (28.2.70). NupUal plumage.
102 2. West Coast Colonies (1) Ihumoana Cliff (Bethell's Beach) This colony at the northern end of Bethell's Beach was first mentioned by Falla (1932) and has since been observed by Petersen (1952-55). During a visit on 8.3.70 one hundred and forty birds was seen, most in post-nuptial plumage. Close observation was not possible but it is highly probably that more birds were present in caves and further round the point. On 14.4.70 a similar number of birds were seen, including some in almost complete pre-nuptial plumage. They lacked only the full brightness of the blue-green eye surround. A number of others had small crests and the white head and neck line of pre-nuptial plumage but possessed only a dull greyish-yellow eye surround and no white nape or rump plumes. No evidence of nesting was seen on either occasion. Petersen notes that nest-building does not normally begin at this colony until July (Turbott 1956). (2) Girdwood Point (Nine miles south of Waikato Heads) Colonies are located on a large basalt stack and on two smaller islands a short distance south, fifty and one hundred yards offshore. On 15.3.70 fifty birds were seen on the two islands and upwards of two hundred on the large stack. Many were in pre-nuptial plumage and some nesting was possibly in progress. In this regard it is interesting to note that E. S. Richardson observed small chicks on 20.4.46 (Turbott 1947). Sibson (1952) gives an account of a visit on 19.10.51 when the colony consisted of at least one hundred and seventy-five breeding pairs, most of which had nests with eggs. (3) Oaia Island This small island, one mile offshore at the south end of Muriwai Beach and three and a half miles north of Bethell's has been recorded as supporting a spotted shag colony. G. and A. T. Wightman (1953, 1956) found nests with eggs on 11.11.51, and, on 29.11.53, a nest with well grown chicks. No recent investigations have been carried out as yet. S U M M A R Y The colonies of Stictocarbo punctatus at Otata, Anita Bay and Tarakihi have increased in numbers since 1956. The data from March April 1970 suggest that the David Rocks colony has decreased in numbers, but since the breeding peak may not be until mid-winter, too much should not be concluded from these observations.
103 The Te Whau Point colony appears to be a new record. Breeding at Ponui Island has not been reported for a number of years (J. Gaunt pers. comm.). ACKNOWLEDGEMENTS I am greatly indebted to Mr. Joe Gaunt (Department of Internal Affairs) for trips to the Noises, Waiheke and Tarakihi, and also for information and advice. I am also grateful to Mr. Roger Gould (Department of Internal Affairs) and Miss Lois Jemmett for assistance in the field. Request for Information Five species of shag have been reported to breed in the Auckland area. They are the Pied (Phalacrocorax varius), Black (P. carbo), Little Black (P. sulcirostris), Little Pied or White throated (P. melanoleucos brevirostris) and Spotted (S. punctatus). Any information concerning locations of, and numbers in, colonies would be much appreciated as would any sightings or recoveries of banded shags. BULLER, W. L., 1888 DAVENPORT, J. C. 1951 FALLA, R. A. 1932 FALLA R. A., 1966 SIBSON, R. B., TURBOTT, E. G. REFERENCES "A History of the Birds of New Zealand". Whitcombe and Tombs, Christchurch, 1961. Summarised Classified Notes. Notornis 4 (3):41. New Zealand Cormorants in the Collection of the Auckland Museum, with notes on field observations. Rec. Auck. Inst. Mus.l (3): 139-154. "A Field Guide to the Birds of New Zealand". Collins. MCKENZIE, H. R. 1948 MURPHY, R. C. 1936 SIBSON, R. B. 1952 STEAD, E. F. 1932 Summarised Classified Notes. New Zealand Notes. 2 (7): 158. "Oceanic Birds of South America". American Museum of Natural History, New York. A North Island Colony of Spotted Shags. Notornis 4 (8): 214. "The Life Histories of New Zealand Birds". Search Publ. Coy., London. Bird TURBOTT, E. G. 1947 Summarised Classified Notes. New Bird Notes 2 (3): 40. Zealand TURBOTT, E. G. 1956 WIGHTMAN, A.T. 1956 WIGHTMAN, G. A. 1953 Notes on the Plumages and Breeding Cycle of the Spotted Shag. Rec. Auck. Inst. Mus. 4 (6): 343-363. Notornis 7 (2). Birds on Oaia 1953-54. Short Notes. Nortonis 7 (2) : 57-60-