New Zealand’s loranthaceous mistletoes Proceedings of a workshop hosted by Threatened Species Unit, Department of Conservation, Cass, 17 – 20 July 1995 Edited by Peter J. de Lange and David A. Norton Published by Department of Conservation P.O. Box 10-420 Wellington, New Zealand 3 ã June 1997, Department of Conservation ISBN 0-478-01906-8 Cataloguing-in-Publication data New Zealand’s loranthaceous mistletoes : proceedings of a workshop hosted by Threatened Species Unit, Department of Conservation, Cass, 17 –20 July 1995 / edited by Peter J. de Lange and David A. Norton. Wellington, N.Z. : Dept. of Conservation, 1997. 1 v. ; 30 cm. Includes bibliographical references. ISBN 0478019068 1. Mistletoes- -New Zealand. 2. Loranthaceae. I. De Lange, Peter James. II. Norton, David A. (David Andrew), 1958– III. New Zealand. Threatened Species Unit. 583.940993 20 zbn97-052606 4 Contents INTRODUCTION 7 1. PAST AND PRESENT DISTRIBUTION OF NEW ZEALAND MISTLETOES 9 Historical distribution of New Zealand loranthaceous mistletoes 11 Status of loranthaceous mistletoes in the Northland Conservancy 23 Status of loranthaceous mistletoes in the Auckland Conservancy 27 Status of loranthaceous mistletoes in the Waikato Conservancy 31 Status of loranthaceous mistletoes in the Bay of Plenty Conservancy 35 Status of loranthaceous mistletoes in the Tongariro-Taupo Conservancy 39 Status of loranthaceous mistletoes in the East Coast Conservancy 43 Status of loranthaceous mistletoes in the Wanganui Conservancy 47 Status of loranthaceous mistletoes in the Hawke’s Bay Conservancy 51 Status of loranthaceous mistletoes in the Wellington Conservancy 55 Status of loranthaceous mistletoes in the Nelson-Marlborough Conservancy 59 Past and present distribution of mistletoes on the West Coast 67 Status of loranthaceous mistletoes in the Canterbury Conservancy 71 Mistletoes in Otago 75 Status of loranthaceous mistletoes in the Southland Conservancy 79 2. ECOLOGY OF NEW ZEALAND MISTLETOES 81 An annotated checklist of New Zealand mistletoe (Loranthaceae) hosts 83 Host specificity and spatial distribution patterns of mistletoes 105 Reproductive ecology of the loranthaceous mistletoes of New Zealand 111 Some aspects of reproduction and possum control of five loranthaceous mistletoes in the central North Island and comparisons with South Island studies 115 Mistletoe moths 125 Population biology of Australian mistletoes 133 3. THREATS TO NEW ZEALAND MISTLETOES 139 Evidence for the impacts of possums on mistletoes 141 An assessment of possum (Trichosurus vulpecula) impacts on loranthaceous mistletoes 149 Decline of New Zealand loranthaceous mistletoes — a review of non-possum (Trichosurus vulpecula) threats 155 Discussion of threats to mistletoes 165 5 4. CURRENT STATUS AND MANAGEMENT SOLUTIONS 169 Conservation status of New Zealand loranthaceous mistletoes: a comment on the application of IUCN Threatened Plant Committee Red Data Book Categories 171 Discussion on status of mistletoes 179 5. CURRENT MANAGEMENT 181 Mistletoe management, Tongariro-Taupo Conservancy 183 Mistletoe protection and monitoring strategies on the West Coast 187 Monitoring a population of Ileostylus micranthus near Wanganui 193 Propagation of mistletoes in the central North Island 197 Discussion on management techniques 201 6. DEVELOPMENT OF A MISTLETOE STRATEGY 203 Discussion on the development of a mistletoe strategy 205 7. BIBLIOGRAPHY OF NEW ZEALAND MISTLETOES 209 Annotated bibliography for New Zealand viscaceous and loranthaceous mistletoes 211 8. APPENDICIES Appendix 1: Mistletoe workshop programme 223 Appendix 2: Mistletoe workshop attendants 225 6 Introduction The loranthaceous mistletoes of New Zealand have long been recognised as attractive, unusual and valued components of our forest flora. Few people will forget the sight of a beech (Nothofagus) forest at the height of summer when the beech mistletoes Alepis and Peraxilla are in full bloom. So spectacular are these flowers, that a small sprig of one of these species, the scarlet mistletoe (Peraxilla colensoi), was selected to grace the front of our former $2 note. This act is the only instance where a nationally listed threatened plant species has been depicted on New Zealand currency. Unfortunately, the reasons behind the choice of flower had little to do with raising public awareness of the need to conserve mistletoes, but rather was a recognition of the flower’s beauty. So it is perhaps today a matter of some irony that at the time of the change to decimal currency, this mistletoe, along with our other Loranthaceae, was a common species, and that now scarlet mistletoe, like the $2 note it once graced, is fast becoming a curiosity of the past. During the 1980s, the decline of our more visible loranthaceous mistletoes became a matter for public concern, culminating in 1985 with the publication of a review article in the popular Forest & Bird journal by Colin Ogle and Peter Wilson entitled “Where have all the mistletoes gone?”. This article prompted widespread national interest in the perceived loss of these showy flowers from the beech forests, and also drew attention to the fact that in many parts of New Zealand the presence of any mistletoe was in itself unusual. The article also prompted a return to researching the biology, anatomy, ecology and physiology of these species, while renewing interest in the possible cause(s) of mistletoe decline, or indeed whether such a decline was really occurring. In 1993 the growing level of interest in the indigenous loranthaceous mistletoes was resulting in problems over the manner in which conservation efforts should be directed, what the research priorities were, and whether they were truly as threatened as the IUCN listings given them by the New Zealand Threatened Plant committee implied. Following on from these wider issues was the need to bring together the wealth of information being gathered on our indigenous mistletoes. The Threatened Species Unit (TSU) of the Department of Conservation was approached to facilitate a workshop to address mistletoe conservation. What resulted was a four day workshop held at the University of Canterbury field station at Cass in July 1995. Invited speakers gave lectures on aspects of mistletoe biology and management, while a breakdown of mistletoe distribution and status was given for each of the Department of Conservation’s 14 conservancies. Discussions followed each session and a plan for a national mistletoe strategy developed. As a result of this gathering it was agreed that the papers presented and accounts given should be published in a proceedings. This publication is the product of this agreement. Both David and I would like to acknowledge the considerable efforts of Suzanne Clegg (formerly of TSU) in helping facilitate the workshop, and Lynette Clelland (S&R editing) for undertaking the final formatting and editing of the following publication. Ian Mackenzie (S&R editing) designed the frontispiece. Peter J. de Lange & David A. Norton (editors) 16 May 1996 7 Part 1 Past and present distribution of New Zealand mistletoes 8 Historical distribution of New Zealand loranthaceous mistletoes Peter J. de Lange Science & Research Division, Department of Conservation, Private Bag 68908, Newton, Auckland David A. Norton Conservation Research Group, School of Forestry, University of Canterbury, Private Bag 4800, Christchurch Brian P.J. Molloy Research Associate, Manaaki Whenua – Landcare Research, Private Bag 69, Lincoln SUMMARY Seven species of loranthaceous mistletoes have been recorded from New Zealand since 1769. These belong to the endemic genera (numbers of accepted species in brackets): Alepis (1), Peraxilla (2), Trilepidea (1) and Tupeia (1). Two other genera, Ileostylus (1) and Muellerina (1) are indigenous to New Zealand, with Ileostylus a near-endemic known elsewhere only from Norfolk Island, while Muellerina celastroides is a possible vagrant from eastern Australia where it is common. 1. INTRODUCTION To determine the historical distribution of all seven indigenous loranthaceous taxa we conducted an extensive search of all New Zealand herbaria (and several overseas institutions). The result is a comprehensive database and associated atlas showing the distribution and extent of loranthaceous decline in New Zealand since 1769 (P.J. de Lange, D.A. Norton & B.P.J. Molloy, unpubl. data). In this paper we summarise some of the main points obtained from our research for this atlas. For convenience we follow the vernaculars suggested by Molloy (1990) e.g., those mistletoes which primarily parasitise beech (Nothofagus) are referred to collectively as “beech mistletoes”, namely Alepis, Peraxilla; while those which are usually associated with seral vegetation and lowland or coastal forest are treated here as “leafy mistletoes”, namely Ileostylus, Muellerina, Trilepidea and Tupeia. de Lange, P.J., Norton, D.A., Molloy, B.P.J. Historical distribution of New Zealand loranthaceous mistletoes. Pp. 11–22 in de Lange, P.J. and Norton, D.A. (Eds) 1997. New Zealand’s loranthaceous mistletoes. Proceedings of a workshop hosted by Threatened Species Unit, Department of Conservation, Cass, 17–20 July 1995. The following notes summarise our understanding of the historical distribution of each of the loranthaceous mistletoe species. Maps showing the distributions derived from herbarium records are appended. 10 2. THE BEECH MISTLETOES Alepis flavida (yellow mistletoe; Fig. 1) This species has been collected from the North and South Islands. In the North Island, it appears to have