Tuhinga 24: 159–204 Copyright © Te Papa Museum of New Zealand (2013) Population sizes of shearwaters (Puffinus spp.) breeding in New Zealand, with recommendations for monitoring Susan M. Waugh1, Alan J.D. Tennyson2*, Graeme A. Taylor 3 and Kerry-Jayne Wilson4 1 Museum of New Zealand Te Papa Tongarewa, PO Box 467, Wellington, New Zealand ([email protected]) 2 Museum of New Zealand Te Papa Tongarewa, PO Box 467, Wellington, New Zealand ([email protected]) 3 Department of Conservation, PO Box 10420, Wellington, New Zealand ([email protected]) 4 PO Box 70, Charleston, New Zealand ([email protected]) * Corresponding author ABSTRACT: We reviewed population data for the nine taxa of shearwaters Puffinus spp. that nest in the New Zealand region. Data for about 350 current breeding colonies were found, and each taxon nested at between three and about 180 localities. We reviewed the information to assess time-series of information for each population and, where possible, to determine trend and total population size. However, few of the species had robust enough information to allow those assessments to be made. We recommend high-priority sites for future monitoring, and encourage other researchers to publish or make available findings from previous work to assist in building a comprehensive picture of the status of shearwater populations. KEYWORDS: New Zealand, shearwaters, Puffinus, population sizes, monitoring, review. Introduction indicator of the richness and health of marine systems in the area managed by the Convention for the Conservation of Seabirds form an important part of the marine ecosystem, Antarctic Marine Living Resources. Species at high trophic and are responsible for the transfer of a large quantity of levels in marine systems can be powerful indicators of nutrients between trophic levels and between marine and change, and long-term datasets on their population changes terrestrial systems. New Zealand has a high diversity of petrel and individual behaviours have been used to indicate and albatross taxa (order Procellariiformes), which includes important changes in global systems such as ocean energy many threatened or rare species, e.g. Chatham Island taiko transfer, circulation and temperature rises. For example, the (Pterodroma magentae (Giglioli & Salvadori, 1869)), as well numbers of breeding emperor penguins (Aptenodytes forsteri as species that are hugely abundant, e.g. sooty shearwater G.R. Gray, 1844) were a key variable in analyses showing the (Puffinus griseus (Gmelin, 1789)) (Taylor 2000a,b). influence of climate change and sea-ice extent on the Marine policy analysts are increasingly turning to Antarctic marine ecosystem (Barbraud & Weimerskirch indicator species to help them define changes in the well- 2001, 2006; Jenouvrier et al. 2009). being of marine systems. For example, Antarctic krill Petrels and albatrosses are typically long-lived and many (Euphausia superba Dana, 1850) abundance is used as an have delayed maturity, breeding for the first time only at 160 Tuhinga, Number 24 (2013) 5–10 years of age (Schreiber & Burger 2002). They are knowledge about each species. However, except in a few superbly adapted to marine environments where resources cases, data are inadequate to allow these analyses. are sparse, and for using oceanographic features that assist 3 To recommend sites for future monitoring of shearwater in concentrating food into dense patches. For example, populations. foraging of shearwaters and albatrosses along upwellings, and 4 To encourage researchers to make available unpublished in relation to movements of top marine predators such as information through subsequent publication or data- whales and dolphins, is well documented (Evans 1982; Au sharing to enable an increasingly comprehensive picture & Pitman 1986). of shearwater population status. However, petrels and albatrosses are less well adapted at responding to rapid – often human-induced – changes in Shearwaters are one of the most abundant groups of seabirds their environment. Such influences may affect them at their in the New Zealand region, with populations numbering in breeding sites, for example through predation by introduced the millions of breeding pairs. Although they are not a mammals or habitat loss; or through interaction with highly threatened group of species (Croxall et al. 2012), industrial and artisanal fisheries. It is estimated that more there is very poor information on several taxa, and for some than 300,000 seabirds are killed annually in fisheries there is no recorded quantitative population estimate. globally (BirdLife International 2012). For New Zealand, Nineteen shearwater taxa are known to occur in the New docu mented mortality in commercial longline and trawl Zealand region, of which nine breed there (Gill et al. 2010). fisheries comprised 2520–4412 individuals in 2008–09 The taxa we discuss fall into three main groups based on (Abraham & Thompson 2011) of more than 30 species of geographic spread: Procellariiformes (Waugh et al. 2008). Climate change and 1 Those with subtropical breeding distributions (two taxa) sea water-warming may also affect some seabird populations – wedge-tailed shearwater (Puffinus pacificus pacificus (e.g. Newman et al. 2009). (Gmelin, 1789)) and Kermadec little shearwater (Puffinus New Zealand is known for its diversity and abundance of assimilis kermadecensis Murphy, 1927). The later taxon Procellariiformes. This has been explained by the ecological breeds only at the Kermadec Islands. richness of the New Zealand Exclusive Economic Zone. 2 Those breeding in temperate areas (five taxa) – Another explanation has been the large extent of the New Buller’s shearwater (Puffinus bulleri Salvin, 1888), flesh- Zealand continental shelf, providing a high degree of footed shear water (Puffinus carneipes Gould, 1844), both ocean productivity and potential niche segregation. fluttering shear water (Puffinus gavia (J.R. Forster, 1844)), The many small islands forming the New Zealand archi - Hutton’s shearwater (Puffinus huttoni Mathews, 1912), pelago may be another driver because of the tendency for and North Island little shearwater (Puffinus assimilis Procellariiformes to nest near their natal site, with more haurakiensis C.A. Fleming & Serventy, 1943). These taxa restricted dispersal to alternative breeding sites than for are endemic to New Zealand, except for the flesh-footed some other bird groups. New Zealand is one of the nations shearwater, which also breeds elsewhere in the Pacific and with the highest number of nesting species and is the Indian oceans. country with the greatest number of endemic and 3 Species found mainly in cool temperate waters and sub- threatened taxa (Croxall et al. 2012). Antarctic waters (two taxa) – sooty shearwater and sub- We conducted an extensive review of both published antarctic little shearwater (Puffinus elegans Giglioli & and unpublished literature to bring together records of Salvadori, 1869). The sooty shearwater also occurs in breeding seabirds throughout the New Zealand region, and smaller numbers in warm temperate waters and has a here present data for the shearwaters (Puffinus spp.). southern oceanic distribution, breeding in Chile, the The objectives of this paper are: Falkland Islands, Australia and New Zealand. Subantarctic 1 To summarise the data available on breeding distribution little shearwaters are known to breed only on the and abundance at each breeding site for the nine shear- Chatham Islands (Aikman & Miskelly 2004) and the sub- water taxa nesting in New Zealand. Antarctic Antipodes Islands within the New Zealand 2 To interpret data to provide information on species trends region, and elsewhere only on a small number of islands and changes in range, and to better define the state of our in the South Atlantic and Indian oceans (Gill et al. 2010). Population sizes of shearwaters (Puffinus spp.) breeding in New Zealand, with recommendations for monitoring 161 Methods and conventions figures, were given (but even ‘counts’ are mostly estimates rather than exact numbers); observed from a distance, where A literature review was conducted using published scientific counts or observations were made from offshore, e.g. from studies, some unpublished reports, and the authors’ own boats or nearby islands. field diaries. These data were compiled in a database with the We assessed possible trends in population numbers only aim of making them available to the research community where two high-quality, recent (post-1990) surveys from through this paper and online resources. Our review builds major breeding sites were available for comparison. Where considerably on other recent reviews of shearwater colonies possible, we estimated the total numbers of breeding pairs (Marchant & Higgins 1990; Hamilton et al. 1997; Taylor for each taxon. 2000a,b; Newman et al. 2009; Baker et al. 2010; Gill et We followed the guidance of the New Zealand gazetteer of al. 2010) but we acknowledge that we have not made an official geographic names in describing sites (Land Information exhaustive review of the literature. New Zealand 2012). Accepted names followed by alternative We followed the taxonomy, nomenclature and sequence names in parentheses are used. Dual names are separated of species as in Gill et al. (2010), with species presented in by a forward slash. The name of island group is listed first, that order in the text and tables. separated from the island name, or further subdivision, by Only breeding records were collated, and included commas. The singular noun