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To view this as a map and many more go to: www.nabis.govt.nz web mapping tool Type the map name into: Search for a map layer or place Lineage – Scientific methodology Breeding distribution of White tern lineage 1. A “breeding colony” for New Zealand seabirds is defined as “any location where breeding has been reported and is considered by the expert compiling the species account to have occurred at that location at least until 2002”. 2. An “occasional breeding colony” for New Zealand seabirds is defined as “any location where breeding has been reported, but not necessarily continuously nor during consecutive breeding seasons, and is considered by the expert compiling the species account to have occurred at that location during the last 30 years”. 3. Literature sources were searched for breeding distribution information. a. Scientific papers, published texts, unpublished reports and university theses available to the expert who prepared the distributional layers. b. Aquatic Sciences and Fisheries Abstracts for 1960-2009. c. OSNZ News and Southern Bird for 1977–2009. 4. Other sources. a. Nil. 5. The mapping of the White tern breeding sites at the Norfolk, Lord Howe and the Kermadec Islands is based on a written description of their location in Higgins & Davies (1996) and Veitch et al. (2004). The sites have not been surveyed for mapping purposes, and the mapping presented is based on the written descriptions of its location. 6. Summary a. An expert scientist integrated information from the literature and expert opinion, and produced hand-drawn distributional zones on a template map. These maps were then digitised and imported into a GIS software package as layers. The areas of the zones were calculated, and the layers were linked to attribute and metadata files. b. The primary sources of breeding distribution data for White tern were papers published in refereed journals. c. The White tern is indigenous in New Zealand, with breeding colonies on Norfolk Island, Lord Howe Island and Raoul Island, in the Kermadec Islands, being the only known nesting sites (Higgins & Davies 1996; Veitch et al. 2004). Elsewhere, it breeds widely on tropical and subtropical islands in the Indian Ocean, Melanesia, central tropical Pacific Ocean, and Hawaii (Higgins & Davies 1993; del Hoyo et al. 1996). d. Breeding populations were estimated at 2000-2500 pairs on Norfolk Island in the mid 1980s and 60-100 pairs on Lord Howe Island in 1990 (Higgins & Davies 1996); at Raoul Island less than 10 pairs bred in 1993-94 (Veitch et al. 2004). More recently, none has been recorded breeding on Raoul Island, although they have been seen prospecting for nest sites, and may already nest on steep cliff faces, since 2004 (Baird 2006). The population is estimated at more than 100,000 pairs worldwide (del Hoyo et al. 1996). e. At Raoul Island, the population has probably declined over the past 100 years as a result of predation. White terns nest on relatively low, near-horizontal branches (Higgins & Davies 1993) and this habit makes the adults, eggs and chicks vulnerable to predation. For example, Bell (1912) found as many as eight pairs, eaten by cats, beneath one tree. In 1913, Iredale reported that the species bred sparingly around the coast of Raoul Island, but Sorensen (1964) reported that he found many pairs in the forest behind Denham Bay during 1944. However, during 1993-94, only three pairs were seen frequenting the Norfolk Pines near the Meteorological Station and Low Flat. The maximum numbers of White terns reported in recent years were up to 20 in flight in March-May 1973, 16 in October 1974, and 10 flying around the canopy of Low Flat Gully on 24 March 1994 (Veitch et al. 2004). If the attempted eradication of cats and rats on Raoul Island during 2002 (Veitch et al. 2004) has been successful, then the population of White terns should increase. f. Numbers of breeding pairs on Norfolk Island may not have changed recently (Higgins & Davies 1996). Breeding was first recorded on Lord Howe Island in 1943, when 4-5 birds were observed; there were about 50 birds present 3 years later and numbers have fluctuated subsequently (Higgins & Davies 1996). 7. References The following sources provided useful information on the breeding distribution of this species. This is not an exhaustive list of all references to the species. Baird, K. (2006). Kermadec Island seabirds. Pp. 13-15 in The state of New Zealand’s birds 2006. Special report New Zealand’s seabirds. Ornithological Society of New Zealand, Wellington. 16p. Bell, R.S. (1912). Breeding habits of white tern (Gygis alba) on Kermadec Group. Emu 12: 26-30. del Hoyo, J.; Elliot, A.; Sargatal, J. (1996). Handbook of the birds of the world. Volume 3, Lynx Edicions, Barcelona. 752p. Higgins, P.J.; Davies, S.J.J.F. (1993). Handbook of Australian, New Zealand and Antarctic birds. Volume 3, Oxford University Press, Melbourne. 1028p. Iredale, T. (1913). Concerning the Kermadec Islands avifauna. Transactions and Proceedings of the New Zealand Institute 45: 78-92. Sorensen, J.H. (1964). Birds of the Kermadec Islands. Notornis 11: 69-81. Taylor, G.A. (2000). Action plan for seabird conservation in New Zealand. Part B: Non-threatened seabirds. Threatened species occasional publication No. 17, Department of Conservation, Wellington. 200p. Veitch, C.R.; Miskelly, C.M.; Harper, G.A.; Taylor, G.A.; Tennyson, A.J.D. (2004). Birds of the Kermadec Islands, south-west Pacific. Notornis 51: 61-90.