NOTORNIS Journal of the Ornithological Society of New Zealand Volume 34 Part 4 December 1987 OFFICERS 1986-87 President - B. BROWN, 20 Redmount Place, Red Hill, Papakura Vice-president - D. E. CROCKETT, 21 McMillan Ave., Kamo, Whangarei Editor - B. D. HEATHER, 10 Jocelyn Crescent, Silverstream Treasurer - W. L. ORMOND, PO. Box 6006, WeIlesley St PO., Auckland 1 Secretary - SUE TRIGGS, PO. Box 12397, Wellington Council Members: BEN D. BELL, Zoology Dept., Victoria University, Private Bag, Wellington BRIAN D. BELL, 9 Ferry Road, Seatoun, Wellington B. J. GILL, Auckland Institute & Museum, Private Bag, Auckland J. HAWKINS, 772 Atawhai Drive, Nelson D. J. ONLEY, Little Totara Farm, Private Bag, Westport H. A. ROBERTSON, Ecology Division, DSIR, Lower Hutt P. M. SAGAR, 38A Yardley Street, Christchurch 4 Conveners and Organisers: Rare Birds Committee: Secretary, Dr M. J. IMBER, P.O. Box 12397, Wellington Beach Patrol: R. G. POWLESLAND, P.0. Box 12397, Rllington Librarian: K. R. BARROW, 67A Taylor Road, Mangere Bridge, Auckland Nest Records: H. A. ROBERTSON, Ecology Division, DSIR, Private Bag, Lower Hutt Banding Liaison Offcer: I;. GURR, 84 Marne Street, Palmerston North Reviews Editor: D. G. MEDWAY, 25A Norman Street, New Plymouth Classified Summarised Notes - North Island: B. R. KEELEY, 4 De Vere Crescent, Hamilton South Island: P. D. GAZE, Ecology Division, DSIR, Private Bag, Nelson S.W. Pacific Island Records: J. L. MOORE, 32 Brook St., Lower Hutt Editor of OSNZ news: I? SAGAR, 38A Yardley St., Christchurch 4 SUBSCRIPTIONS AND MEMBERSHIP Annual Subscripion: Ordinary Member $30; Husband & Wife members $45; Junior Member (under 20) $1 5; Life Member $600; Family member (one Notornis per household); being other Eamily of a member in the same household as a member, $15; Institution $60; Overseas member and overseas institytion $6.00 extra (postage). Subscriptions are for the calendar year of first joining and are renewed by invoice each January. Please pay promptly to ensure receiving Notomis and OSNZ news. Applications for membership, changes of address, resignations and advice on non-delivery of Notornis and OSNZ news should be sent to:- Membership Secretary, The Ornithological Society of N.Z. Inc., PO. Box 6006, Ellesley St. PO., Auckland 1. Exchanges and library subscriptions should be sent to the Treasurer. Editorial matters ONLY should be sent to the Editor. [Registered with the GPO Gisborne as a publication] ISSN 0029-4470 CONTENTS BARTLE, J. A., SAGAR, P.M. Intraspecific variation in the New Zealand Bellbird. ............................................................25 3 READ, A. F., (YDONNELL, C. F. J. Abundance of Yellowheads in the Hawdon River valley, Arthur's Pass National Park, in 1983 and 1984 .......................................................................307 BEAUCHAMP, A. J. The social structure of the Weka (GaIlitallus azrstralis) at Double Cove, Marlborough Sounds.................. 317 POWLESLAND, ,R.G., ROBERTSON H. A. Changes in Gull numbers and notes on other birds of the Otaki-Ohau coast . 327 Short Notes BROUWER, P. and S., BINNING, B. Skuas mobbing Black-backed Gulls ............................... .... .................................... 306 MORRISON, K. Cattle Egrets in Fiordland National Park 1973-1987 3 15 DOWDING, J. E. A beach-wrecked White-naped Petrel............. 325 Obituary - Count K. A. Wodzicki OBE,'PLD, DSc, FRSNZ .... 339 Notice ...................................................................................342 Letter ...................................................................................343 1st International Conference on Penguins 16-19 August 1988 - Dunedin, N.Z. Curmat resend sad antdevelopments For furtber information please write te: 1st International Conference on Penguins University Extension University of Otago P.O. Box 56 Dunedin, New Zealand. Printed by TE RAU PRESS LTD, Peel St-. GLbomc REGIONAL REPRJSENTATIVES FAR NORTH: Vacant. NORTHLAND: D. E. Crockett, 21 McMillan Ave., Kamo, Whangarei. Ph. 50-954. AUCKLAND: M. J. Xylor, 28 Awarua Crescent, Orakei, Auckland 5. Ph. 549-234. SOUTH AUCKLAND: Anthea Goodwin, RD1, Clwedon. WAIKATO: Stella Me, 1 Corrin St., Hamilton. Ph. 435-199 BAY OF PLENTY: F! C. M. Latham, 72 Simpson Road, Papamoa Beach, Ph. 420-406 Tauranga. VOLCANIC PLATEAU: J. G. Innes, Loop Road, Okareka, Rotorua. Ph. 28-107. GISBORNEIWAIROA: J. C. Henley, 61456 Aberdeen Rd.. Gisborne. Ph. 81-581. TARANAKI: D. G. Medway, 25A Norman Street, New Plymouth. MANAWATU: L. J. Davies, Stace's had, RD1, Falmerston North. WANGANUI: ) Ph. 70-159. HAWKES BAY: K. V. Todd, 21416 E. Heretaunga Street, Hastings. Ph. 82-172. WAIRARAPA: Vacant. WELLINGTON. R. N. Thomas, 6 Satara Crescent, Khandallah, Wellington 4. Ph. 791-165. NELSON: J. Hawkins, 772 Atawhai Drive, Nelson. Ph. 520-151. MARLBOROUGH: Beverley North, PO. Box 341, ~leheirn.9. 88-585. CANTERBURY: B. R. Armstrong (acting), 60 Frankleigh Street, Christchurch 2. Ph. 324-784. WEST COAST C. S. Lauder, 9 Winnie Street, Greymouth. Ph. 6349. OTAGO: I? Schweigman, 121 Maryhill Terrace, Maryhill, Dunedin. Ph. 52-790. SOUTHLAND: W. J. Cooper, 218 Chelmsford Street, Invercargill. Ph. 75-281. LITERATURE AVAILABLE From all bookshops: Collins guide to the birds of New Zealand by R. A. Falla, R. B. Sibson and E. G. Turbott $30.25 From M. Bishop, Maungakura Road, R.D.3, Helensville: Back numbers of 'Notornis': Fdrts of Vo1. 1-25, $3.OO per art: Vols. 26-29, $5.00 per part; Vpls. 30-34 $6.00 per part; dplus 10% for postage and pack m Nk). Re rts and bulletms (1938-?4$) 0%~Library catalogue (1976 ed) 17 pp. Bandin re orts, Nos. 8-14 554 each Kermadiec hqxdition 19d, b A. T. Edgar. Amendments & ~ddifionsto 1570 ChecM~st. NOTORNIS is the journal of the Ornithological Society of New Zealand (Inc.) Editor B. D. Heather, 10 Jocelyn Crescent, SILVERSTREAM VOLUME 34 PART 4 DECEMBER 1987 INTRASPECIFIC VARIATION IN THE NEW ZEALAND BELLBIRD Anthornis melanura By J. A. BARTLE and P. M. SAGAR ABSTRACT Intraspecific variation in morphometrics, plumage colouration, moult and breeding is described and its taxonomic significance assessed. There is a latitudinal cline in morphometrics and colouration among mainland, nearshore island, and Auckland Is populations. Southern bellbirds are larger and more brightly coloured, but they have shorter bills. Intensity and hue of the iridescent head and olive-green plumage colouration are determined by the degree of melanism, which increases southward and on all isolated islands but the Three Kings. Age and sex differences in plumage colouration are also caused by the different degrees of melanism. The degree of melanism may be reduced by the dryness of the environment, particularly in the period before moult. Overlain on this cline are insular trends in morphometrics, colouration, moult, and breeding pattern. Bellbirds, particularly males, from isolated islands are larger than those on the mainland, whereas clutches are fewer and smaller, and breeding seasons and adult moult earlier. The sue increase occurs whether other species of honeyeater are present or not and may result from high densities and the increased tendency of males and females to use different feeding niches. The relative body proportions of island populations vary and wing length does not increase as rapidly as body size. A new subspecies is described from the Poor Knights Is. It is characterised by a distinctly blue rather than violet iridescent head in males, an immature plumage phase, and other differences in sue, relative proportions, breeding, and time of moult. The nomenclature and taxonomic status of other island subspecies and of the extinct Northland bellbird A. dumerilii are reviewed. A. dumerilii and A. incoronara are regarded as synonyms of A.m. melanura. CONTENTS INTRODUCTION MATERIAL AND METHODS NOMENCLATURE Cenhia melanura Sparrman, 1786 Philedon dumerilii Lesson & Garnot, 1828 Anthornis melanocephala G. R. Gray, 1843 Anthornis incoronata Bangs, 191 1 Anthornis melanura obscura Falla, 1948 NOTORNIS 34: 253-306 (1987) 254 BARTLE AND SAGAR BREEDING Three Kings Islands Poor Knights Islands Mainland New Zealand Chatham Islands Conclusion PLUMAGES AND MOULT CYCLES IN BELLBIRDS Poor Knights Islands Mainland New Zealand Auckland Islands Chatham Islands Three Kings Islands Conclusion PLUMAGE COLOURATION IN BELLBIRDS Plumage colouration and the role of melanin Variation with age and sex Patterns of clinal and insular variation Discussion MORPHOMETRIC VARIATION IN BELLBIRDS Variation with sex and age Clinal variation Variation in island populations CAUSES OF CLINAL AND INSULAR VARIATION Expansion of niche width on islands Changes in size and colour Summary TAXONOMIC SIGNIFICANCE OF BELLBIRD VARIATION Criteria used for subspecific recognition The extinct bellbird of Northland: Philedon dumerilii Lesson & Garnot, 1828 Current status of Anthornis incoronata Bangs, 1911 Current status of A. melanocephala G.R. Gray, 1843 Current status of A. melanura obscura Falla, 1948 Anthornis melanura oneho n. subsp. Proposed subspecific arrangement INTRODUCTION Of the 19 indigenous passerine bird species still living in New Zealand, three are honeyeaters (Meliphagidae). Each of these honeyeaters represents a different endemic genus. They eat somewhat different foods obtained by different foraging habits (Craig et al. 1981a). All three are sympatric, but the Stitchbird (Notiomystis cincta) is now confined to Hen, Cuvier, and Little Barrier Islands. Bellbirds (Anthornis melanura) are widespread in New Zealand, from the subtropical Three Kings