Under the Resource Management Act 1991

Transcription

1 Before a Special Tribunal Under the Resource Management Act 1991 In the matter of an application for a Water Conservation Order for the Ngaruroro River and Clive River Statement of evidence of Rachel Katherine McClellan on behalf of the New Zealand Fish and Game Council; Hawke's Bay Fish and Game Council; Royal Forest and Bird Protection Society of New Zealand; Jet Boating New Zealand; Whitewater NZ Incorporated; and Operation Pātiki Ngāti Hori ki Kohupātiki 12 December 2018

2 Introduction 1 My name is Rachel McClellan. I am the principal avifauna ecologist with Wildland Consultants Ltd (Wildlands), based in Wellington. I have worked for Wildlands for nine years. I have undertaken avifauna work across New Zealand, including survey and monitoring, assessments of effects, threatened species monitoring and management, development of ecological significance criteria, and strategic and restoration plan development and implementation. 2 I have been engaged by Royal Forest and Bird Protection Society of New Zealand to provide expert evidence on birds in relation to the application of a Conservation Order for the Ngaruroro River, Hawke's Bay. 3 I visited sites along the length of the upper and lower Ngaruroro River on 3 October Qualifications and experience 4 I have the following qualifications and experience: (a) (b) (c) Degrees of Bachelor of Science in Zoology and Botany from Victoria University; Master of Conservation Science (with Distinction). My thesis was on the breeding biology of the Nationally Vulnerable flesh-footed shearwater (Puffinus carneipus) on Karewa Island (Victoria University, 1996); and PhD in Zoology. My thesis investigated the ecology and management of the Nationally Critical black-billed gull (Larus bulleri) (University of Otago, 2009). 5 I am a member of the New Zealand Ecological Society and Birds New Zealand (brand name of the Ornithological Society of New Zealand). 6 I have prepared expert evidence for 15 Council, Environment Court, and Tribunal hearings addressing issues such as river conservation orders, coastal subdivisions, mining applications, wind farms, hydropower proposals, and council plan changes. Hearings have included the provision of avifauna evidence for the Oreti River Conservation Order hearing (for Fish and Game New Zealand), and for Meridian Energy's North Bank Tunnel proposal on the braided Waitaki River (for the Lower Waitaki River Management Society). 7 I have considerable experience in river bird, seabird and shorebird ecology. I completed my PhD on the Nationally Critical black-billed gull, which examined population trends, the impacts of introduced and native predators, the impact of flows on productivity, and the species' relationship with agricultural ecosystems page 1

3 Since then, I have remained involved with the monitoring and management of threatened bird species on braided rivers, including providing expert advice for the Department of Conservation's braided rivers management plan, and the analysis of 50 years of black-billed gull monitoring data from South Island rivers. 8 Examples of other projects include: review of the Department of Conservation's Fiordland crested penguin (Eudyptes pachyrhynchus) monitoring programme; review of the Yellow-eyed Penguin Trust's work on yellow-eyed penguins (Megadyptes antipodes) on Rakiura (Stewart Island); avifauna (including seabird) restoration and management components of the Department of Conservation's Dusky Sound Restoration and Conservation plan, and the Project Janszoon restoration plan for Abel Tasman National Park; restoration plan for Long Point, Catlins, including reintroduction of seabird species including albatross; aerial surveys of Canterbury rivers for black-billed gulls; and provision of expert evidence on the effects of the Rena wreck on seabirds and shorebirds. 9 I presented evidence to this Special Tribunal regarding the bird habitat values of the upper Ngaruroro as part of the Stage 1 Hearing. 10 While this is not a hearing before the Environment Court, I confirm that I have read the code of conduct for expert witnesses contained in the Environment Court Consolidated Practice Note (2014). I have complied with it when preparing my written statement of evidence and I agree to comply with it when presenting evidence. I confirm that the evidence and the opinions I have expressed in my evidence are within my area of expertise. I have not omitted to consider material facts known to me that might alter or detract from the opinions that I express. Scope of evidence 11 For the purpose of the Stage 2 hearing of this Water Conservation Order application, I have been directed to provide evidence on bird habitat of the lower Ngaruroro River. The scope of this statement of evidence is as follows: (a) (b) (c) (d) (e) Overview of bird habitats of the Ngaruroro catchment; Overview of the birds of the Ngaruroro catchment; Relevant surveys and reports of Ngaruroro River avifauna; The ecological significance of the habitats and bird species of the lower Ngaruroro; Comparison with other braided rivers protected by Water Conservation Orders; page 2

4 (f) The potential effects of river modifications on the habitats and bird species of the lower Ngaruroro; and (g) The lower Ngaruroro as outstanding habitat for birds. Summary 12 The lower Ngaruroro is the second largest braided river in the North Island, a historically rare ecosystem in New Zealand, and rare internationally. 13 The bird habitats of the lower Ngaruroro are of an outstanding nature as they: (a) Support a high diversity of waterbirds, including South Island pied oystercatcher, which breeds on no other river in the North Island, and black-billed gull (Nationally Critical), which is rare in the North Island; (b) Support one of the largest known populations in New Zealand of each of banded dotterel (Nationally Vulnerable), black-fronted dotterel (At Risk- Naturally Uncommon), and pied stilt (Not Threatened); (c) Support greater than 5% of the national populations of banded dotterel and black-fronted dotterel, and more than 1% of pied stilt population; and (d) Are part of a system of wetlands in the lower Ngaruroro area, including Waitangi Wetland, that may support more than 1% of the Australasian bittern population (Nationally Critical). Overview of bird habitats of the Ngaruroro River and its tributaries 14 The Ngaruroro River is one of the North Island's largest braided rivers 1. The river can be divided into five main sections: (a) The upper reaches of the river above the gorge at Whanawhana (and its tributaries) which are mostly single channel. The upper reaches and tributaries flow through steep, rugged country which mostly comprises regenerating scrub and forest and some commercial pine plantations. The upper Ngaruroro and its many tributaries support a significant population of blue duck or whio, a specialist species of waterfowl dependent on high quality, fast flowing water; (b) The reaches between Whanawhana and the Fernhill Bridge which are extensively braided. Hundreds of hectares of bare gravels are available for New Zealand's specialist braided river bird species, all of which are 1 Wilson G. 2001: National distribution of braided rivers and the extent of vegetation colonisation. Landcare Research Contract Report LC0001/068. Prepared for the Department of Conservation, Twizel page 3

5 Threatened or At Risk. At least one tributary of this reach, Big Hill Stream, supports a small population of whio. This section also includes the only significant freshwater swamp associated with a river in Hawke's Bay 2. Pigsty Swamp is an oxbow wetland caused by movement of the river away from the original channel, and is located approximately six kilometres downstream of the Whanawhana cableway, and drains to the river mainstem. A number of specialist wetland bird species such as Australasian bittern have been reported from this wetland; (c) The reach between Fernhill and the Chesterhope Bridge, which is less braided and mostly single channel, which also contains wide expanses of bare gravels that support braided river bird species; (d) The reach between the Chesterhope Bridge and the Waitangi Estuary and associated wetlands, which is largely channelised; and (e) The Waitangi Estuary and associated wetlands, including the gravel bars, and the Horseshoe Wetland. A diverse range of bird species are found at the estuary. Some bird species that roost or breed at this location will forage in the lower Ngaruroro, just as birds breeding in the lower Ngaruroro may feed in the estuary and wetlands. 15 This evidence addresses the bird values of the lower Ngaruroro River. Overview of the bird community of the Ngaruroro catchment 16 The bird community of the Ngaruroro catchment has been described by two authors, Dr Brent Stephenson 3 and Dr Richard Seaton 4, who both include terrestrial birds in their species lists. Dr Stephenson lists 83 bird species that inhabit the upper and lower riverbed, riparian habitats, freshwater wetlands, and the Waitangi Estuary and associated habitats. Dr Seaton lists 93 species that have been recorded from the Ngaruroro catchment since the early 1960s; his list includes some species that are now unlikely to be present (such as brown kiwi). Both authors include birds that are rare visitors to the river and estuary. I provide a combined list of all species in Appendix The combined list contains 58 bird species that are dependent on the river for some stage of their lifecycle. I have called these species 'waterbirds'. This list Parrish G.R. 1988: Wildlife and wildlife habitat of Hawke's Bay rivers. Science & Research Series 2. Department of Conservation, Wellington. Stephenson B.M 2010: Final report baseline study and assessment of effects on braided riverbed bird communities. Unpublished report, Eco-Vista Photography & Research Ltd. 59p Seaton R. 2014: Assessment of outstanding avifauna values on the Ngaruroro River. Report prepared for the New Zealand Forest and Bird Protection Society. The Catalyst Group. 13p page 4

6 includes, for example, seabirds that venture into estuarine habitats such as the Australasian gannet (Morus serrator), shags, herons, oystercatchers, gulls, terns, international migratory waders, and waterfowl. Most of these species are restricted to the estuarine and braided habitats of the lower Ngaruroro River. 18 In contrast, the upper Ngaruroro and its tributaries support significantly fewer species of waterbirds. The primary species of conservation importance known from the upper Ngaruroro is blue duck. The upper Ngaruroro was addressed in my evidence for the Stage 1 Hearing. Relevant surveys and reports of lower Ngaruroro avifauna 19 Six historical surveys of lower Ngaruroro River waterbirds have been undertaken in the years 1962, 1967, 1972, 1984, 1986, and Surveys in 1962, 1967, and 1972 were undertaken by the Ornithological Society of New Zealand (OSNZ; now Birds New Zealand); in 1984 and 1986 by the New Zealand Wildlife Service; and in 1993 by the Department of Conservation. The OSNZ surveys and Wildlife Service surveys are summarised in Parrish (1998) More recently, a section of the lower Ngaruroro between Otamauri Stream and Maraekakaho, a distance of some 17 kilometres, was surveyed in 2010 by Dr Brent Stephenson (approximately one third of the lower river) 6. Stephenson summarises all historical surveys in his report. 21 In 2016, Hawke's Bay Regional Council undertook an aerial survey of several of the main rivers, as well as the coast, for black-billed gulls. 22 Finally, a survey of the lower Ngaruroro from the Whanawhana cableway to State Highway 3 was undertaken in November 2018 by the Department of Conservation and Birds New Zealand. 23 In contrast to the intermittent surveys of the lower Ngaruroro, the birds of Waitangi Estuary and its associated wetlands have been regularly surveyed for decades. For example, annual winter and summer counts from Ahuriri Estuary, Westshore Lagoon, East Clive, Waitangi Estuary, and Tukituki Estuary between 1983 and 2003 have been analysed as part of two scientific publications assessing the stability of national wader populations 7, Parrish G.R. 1988: Wildlife and wildlife habitat of Hawke's Bay rivers. Science & Research Series 2. Department of Conservation, Wellington. Stephenson B.M 2010: Final report baseline study and assessment of effects on braided riverbed bird communities. Unpublished report, Eco-Vista Photography & Research Ltd. 59p. Sagar P.M., Shankar U. and Brown S. 1999: Distribution and numbers of waders in New Zealand, Notornis 46: page 5

7 24 In addition to the surveys, several assessments of the biodiversity values and, in particular, the bird values of the Ngaruroro have been completed. The first of these was the New Zealand Wildlife Service's report in 1998 that, in addition to summarising survey results of the Tukituki, Tutaekuri, Ngaruroro and Mohaka, also assessed the values of those rivers using the Sites of Special Wildlife Interest (SSWI) criteria. 25 The second assessment was done as part of the Protected Natural Areas Programme in 1993, involving the survey of remaining natural areas within the Heretaunga Ecological District. 26 A further assessment was undertaken in 2012 using the River Values Assessment System (RiVAS), which applied criteria to assess existing value and potential value of every river in the Hawke's Bay for birds. The SSWI and RiVAS assessments are discussed in greater detail in paragraphs As previously mentioned, two unpublished reports by Stephenson (2010) 9 and Seaton (2014) 10, specifically discuss the bird values of the upper and lower Ngaruroro River. 28 Lastly, Hawke's Bay Regional Council has published or commissioned several reports which summarise habitat and fauna values, condition, and management of the Ngaruroro River and its estuary. These include publications relating to the management of water within the Tutaekuri, Ahuriri, Ngaruroro and Karamu catchments (or TANK) 11, a biodiversity inventory for the region 12, and the Ecological Management and Enhancement plan for the Ngaruroro River flood protection and drainage scheme Southey I. 2009: Numbers of waders in New Zealand DOC Research & Development Series 308. Department of Conservation, Wellington. 70 p. Stephenson B.M 2010: Final report baseline study and assessment of effects on braided riverbed bird communities. Unpublished report, Eco-Vista Photography & Research Ltd. 59p. Seaton R. 2014: Assessment of outstanding avifauna values on the Ngaruroro River. Report prepared for the New Zealand Forest and Bird Protection Society. The Catalyst Group. 13p. For example, Madaraz-Smith A., Wade O., Wade H. and A. Hicks 2016: The estuaries of the TANK catchments: Ahuriri and Waitangi estuaries. HBRC Report No. RM Hawke's Bay Regional Council, Napier. Hashiba K., Wade O. and W. Hesketh 2016: Hawke's Bay biodiversity inventory: current state of knowledge. HBRC Report No. RM 13/ Hawke's Bay Regional Council, Napier. MWH 2011: Ngaruroro River flood protection and drainage scheme Ecological management and enhancement plan. HBRC Report No. AM Prepared for Hawke's Bay Regional Council, Napier page 6

8 The Ngaruroro in the context of New Zealand's braided rivers 29 Braided riverbeds are considered a historically rare ecosystem in New Zealand 14. Braided rivers like the lower Ngaruroro are mostly found in erosion-prone areas around the world, being most common in parts of North America, the Himalayas, the Artic, and New Zealand 15. Globally, the lower reaches of braided rivers are often extensively modified by impounding of water, modification of margins, and the taking of surface and ground waters 16. New Zealand is no exception to this, and there are extremely few braided river systems in New Zealand that retain indigenous riparian vegetation, have limited invasive weed issues, and are free from water abstraction. 30 One hundred and sixty-three rivers have been identified as having one or more areas of braided habitat along their length; almost 80% of these rivers are located in the Canterbury and West Coast regions 17. In contrast, the North Island has only 31 rivers with braided habitat, or 19% of the national total. Ten of these rivers are in the Gisborne and Hawke's Bay regions. The majority of these North Island rivers have a relatively small amount of braided habitat, generally less than c.500 hectares. The total area of North Island braided rivers is estimated to be 2.2% of the total national area 18. The table below lists the details of the five North Island rivers with the greatest amount of habitat and compares those to the five largest braided rivers in New Zealand, including the iconic Rakaia River Williams, P.A., Wiser, S., Clarkson, B. and Stanley, M.C., New Zealand's historically rare terrestrial ecosystems set in a physical and physiognomic framework. New Zealand Journal of Ecology, pp O'Donnell C.F.J., Sanders M., Woolmore C. and Maloney R.F. 2016: Management and research priorities for conserving biodiversity on New Zealand's braided rivers. Department of Conservation, Wellington, New Zealand. 46 p. Gray D. and Harding J.S. 2009: Braided river benthic diversity at multiple spatial scales: a hierarchical analysis of β diversity in complex floodplain systems. Journal of the North American Benthological Society, 28: Wilson G. 2001: National distribution of braided rivers and the extent of vegetation colonisation. Landcare Research Contract Report LC0001/068. Prepared for the Department of Conservation, Twizel. O'Donnell C.F.J., Sanders M., Woolmore C. and Maloney R.F. 2016: Management and research priorities for conserving biodiversity on New Zealand's braided rivers. Department of Conservation, Wellington, New Zealand. 46 p page 7

9 Table 1: Largest braided rivers in the North and South Islands by area (data from Wilson 2001) 19 Region Total Habitat (ha) Amount of River Unvegetated or Open Habitat (ha) North Island Tukituki Hawke's Bay 5,589 2,367 Ngaruroro Hawke's Bay 3,500 1,597 Waiapu Gisborne 2,511 2,163 Rangitikei Wanganui-Manawatu 2, Tutaekuri Hawke's Bay South Island Rakaia Canterbury 32,102 21,853 Rangitata Canterbury 18,091 11,249 Waimakariri Canterbury 14,349 10,487 Waitaki Canterbury 8,104 3,509 Waiau Canterbury 7,413 5, The Ngaruroro is the second largest braided river in the North Island by area, and the seventeenth largest braided river in the country of a total of 163 braided rivers. 32 The lower Ngaruroro provides a variety of habitats that are used by different groups or guilds of bird species 20. The shag species are open water divers, taking fish or invertebrates from deep channels. Deep water waders, such as oystercatchers, stilts and herons, have long legs and can take advantage of deeper waters in the river. Short-legged waders like dotterels are restricted to shallower water along the edges of channels and backwaters. Swans, geese and most duck species dabble while floating in slower moving waters of rivers, or graze vegetation including pasture. Terns and black-billed gull can take invertebrates on the wing or from the surface of the water, though both will also wade. 33 Braided rivers also provide a variety of breeding habitats for the above species. Shags will often nest and roost alongside rivers in tall trees such as willow, but also in shrubs, and sometimes on the ground in wetlands or on cliffs. Riparian vegetation is mostly used by waterfowl. The open, bare gravel of braided riverbeds is used for nesting by species such as dotterels, oystercatchers, terns and gulls Gisborne's Waiapu River has the highest suspended sediment yield of any river in New Zealand, and one of the highest in the world, due to forest clearance in the catchment and excessive erosion rates. Canterbury's Waitaki River flow is entirely managed via a system of hydrodams. O'Donnell C. 2004: River bird communities. In: Harding J., Mosely P., Pearson C. and Sorrell B. Freshwaters of New Zealand. New Zealand Hydrological Society and the New Zealand Limnological Society page 8

10 34 The lower Ngaruroro, and other braided rivers of the North Island, share some differences from South Island braided rivers in that they do not support breeding populations of some braided river specialists such as the Nationally Critical black stilt and the Nationally Endangered black-fronted tern, and hold very small numbers of the Nationally Critical black-billed gull. 35 However, the lower Ngaruroro stands out from the crowd as the only North Island river with a breeding population of South Island pied oystercatcher (At Risk- Declining), one of very few North Island rivers that regularly support black-billed gull, one of the first known locations of breeding black-fronted dotterel (At Risk- Naturally Uncommon) which has now developed into one of New Zealand's most important populations, and one of the largest populations of banded dotterel (Threatened-Nationally Vulnerable) and pied stilt (Not Threatened) in New Zealand. I will discuss these in detail in subsequent sections. The bird community of the lower Ngaruroro River 36 As noted above, the bird community of the entire Ngaruroro River has been described by two authors. Stephenson lists 83 bird species that inhabit the riverbed, riparian habitats, freshwater wetlands, and the Waitangi Estuary and associated habitats. Seaton lists 93 species that have been recorded from the catchment since the early 1960s, and includes some species that are now unlikely to be present (such as brown kiwi). Both authors include birds that are rare visitors to the river and estuary. I provide a combined list of all species in Appendix I have addressed the national significance of the upper Ngaruroro and its tributaries in detail in my evidence for the first hearing. I will briefly discuss the significance of other habitats and bird species of the wider Ngaruroro area in paragraph 79. I realise that this hearing is not concerned with the Ngaruroro below the inland limit of the coastal marine area. However, I consider it important to at least briefly address the avifauna values of the estuary and associated wetlands, as some bird species present in the lower Ngaruroro are likely to use these habitats, and water management in the upper and lower Ngaruroro has the potential to affect these values. 38 The lower Ngaruroro River supports regular populations of 14 waterbird species, 12 of which are indigenous. Of those, five to six species are ecologically significant: black-billed gull (Nationally Critical), banded dotterel (Nationally Vulnerable), South Island pied oystercatcher (At Risk-Declining), black-fronted dotterel (At Risk-Naturally Uncommon), pied stilt (Not Threatened), and Australasian bittern (Nationally Critical). I will discuss each in turn in the following sections page 9

11 39 I use 1% and 5% national population thresholds for determining ecological significance in the following paragraphs. The 1% threshold derives from one of the criteria developed to identify Wetlands of International Importance (the "Ramsar List"; see paragraphs 97-99). The threshold has also been adopted by BirdLife International in its programme to identify globally Important Bird or Biodiversity Areas (or IBAs), where a site is known or thought to hold congregations of 1% of the global population of one or more species on a regular or predictable basis. Over 12,000 IBAs have now been identified around the world including New Zealand. 40 The 5% level is a threshold that has been used in several applications for Water Conservation Orders in New Zealand as representing an outstanding habitat page 10

12 Table 2: Counts of waterbird species in the lower Ngaruroro River: Species Threat Classification Black-billed gull Threatened-Nationally Critical Grey duck Threatened-Nationally Critical Banded dotterel Threatened-Nationally Vulnerable ,101 Wrybill Threatened-Nationally Vulnerable South Island pied oystercatcher At Risk-Declining Black-fronted dotterel At Risk-Naturally Uncommon Black shag At Risk-Naturally Uncommon Little black shag At Risk-Naturally Uncommon * 0 0 Australasian shoveler Not Threatened Grey teal Not Threatened Little shag Not Threatened present Paradise shelduck Not Threatened Pied stilt Not Threatened Southern black-backed gull Not Threatened 2,125 5,032+ 1,600 2,056 2,134 1, ,320 Spur-winged plover Not Threatened White-faced heron Not Threatened Canada goose Introduced * 0 20 Mallard Introduced NOTES: Approximately 49 kilometres surveyed in all years except 2010 when c.12 kilometres surveyed survey used 2-3 observers per reach following best practise guidelines for wide braided rivers; previous surveys appear to have used a single observer. Empty cells signify no data available. '+' sign indicates observers were not confident all individuals had been sighted page 11

13 Black-billed gull (Threatened-Nationally Critical) 41 Black-billed gull (Larus bulleri) is one of New Zealand's most threatened bird species. Unlike most Nationally Critical bird taxa, it still has a large population that numbers in the tens of thousands, but has undergone a rapid decline. Recent modelling of South Island data across 52 years ( ) from 30 South Island rivers predicts a continuing decline of approximately 75% over the next 30 years Despite undergoing widespread decline in the South Island, black-billed gull have increased their range in the North Island in recent decades: black-billed gulls were first observed breeding in the North Island in 1932 with red-billed gulls in Lake Rotorua; in 1954 colonies were found at Gisborne Harbour and the Ngaruroro River mouth; a colony was observed on Matakana Island in Tauranga Harbour in 1967; breeding was confirmed on the Manawatu River by 1972; and nesting was not observed around the Auckland area until However, the increasing distribution does not appear to be associated with increasing abundance in the North Island Most recently, a national census of black-billed gulls in recorded a national total of 60,256 nests, of which 992 nests, or 1.6%, were in the North Island 24. Only 19 nests were found in the Hawke's Bay region (main rivers and coastline were surveyed). 44 However, previous records in the Hawke's Bay have recorded some of the largest colonies in the North Island, such as the Ngaruroro River (1980, 270 birds; 2009, 150 birds), the Waitangi Estuary (1997, 250 birds), and Napier Wharf (2015, 150 birds). 45 The November 2018 survey of the lower Ngaruroro recorded a colony of 263 birds in the section between Pigsty Swamp and Whakamarumaru. This is one of the largest colonies ever recorded in the Hawke's Bay. The Ngaruroro and the Waitangi estuary are often used by black-billed gulls, although not every year. At Waitangi Estuary, black-billed gulls nest on the raised gravel beach near the river mouth. When nesting on the lower Ngaruroro itself, colonies have generally been Wildland Consultants (McClellan R.K. and Smith D.V.S) 2015: Population trends of black-billed gulls (Larus bulleri) on South Island rivers ). Wildland Consultants Report No Prepared for Department of Conservation, Christchurch. 21 pp. Southey I. 2007: Black-billed gulls: another threatened species in the Firth of Thames. Miranda News. McClellan, R.K.; Habraken, A [updated 2017]. Black-billed gull. In Miskelly, C.M. (ed.) New Zealand Birds Online. Mischler C. 2017: Estimating the breeding population of black-billed gulls Larus bulleri in New Zealand, and methods for future count surveys. Notornis 65: page 12

14 located several kilometres up river, often near the Mangatahi Stream confluence. In some years, such as 2018, the numbers of black-billed gulls present on the river or at the river mouth would comprise a significant proportion of the total North Island population. 46 The unpredictable presence of black-billed gulls is characteristic of the species. The species does not necessarily re-use colony sites. Individuals can move between rivers both within seasons and between years; rivers can have no gulls in some years, and gulls in others 25. For example, two important Canterbury rivers for black-billed gulls are the Waiau and Ashburton. The Waiau supported no gulls in 2014, 1,181 nests in a single colony in 2015, and 511 nests in three colonies in The Ashburton supported 727 nests in 2015, and 4,686 nests in 2016 (no survey was conducted in 2014) No location in the North Island meets the 1% threshold for black-billed gulls, and it is possible that such a threshold may never be met anywhere within the North Island. However, in my opinion, regularly used sites which support larger colonies within the North Island, such as the lower Ngaruroro, should be regarded as nationally important as the success of larger colonies may help maintain the species' population in the North Island. This is because larger colonies may have higher productivity than smaller colonies; a finding from my PhD research on black-billed gulls in Southland 27, and recently supported by research on blackfronted terns The regular presence of black-billed gull colonies on the river adds considerably to the outstanding bird habitats of the lower Ngaruroro. Banded dotterel (Threatened-Nationally Vulnerable) 49 Banded dotterel (Charadrius bicinctus bicinctus) is an endemic species that breeds throughout New Zealand, from coastal beaches, to inland rivers, to terrestrial habitats such as the Central Plateau. On rivers, the solitary nests of banded dotterels tend to be on sparsely vegetated gravels. An unusual feature of the species is that birds from different areas have different post-breeding McClellan R.K. 2008: Ecology and management of the black-billed gull in Southland. PhD thesis. Otago University. Mischler C. 2017: Estimating the breeding population of black-billed gulls Larus bulleri in New Zealand, and methods for future count surveys. Notornis 65: McClellan R.K. 2008: Ecology and management of the black-billed gull in Southland. PhD thesis. Otago University. Schlesselmann A-K.V., O'Donnell C.F.J., Monks J.M. and Robertson B.C. 2018: Clearing islands as refugia for black-fronted tern (Chlidonias albostriatus) breeding colonies in braided rivers. New Zealand Journal of Ecology page 13

15 movements. Those that breed at coastal locations tend to be sedentary, and remain in much the same location throughout the year. In contrast, those breeding on rivers or at other inland locations are mostly migratory. For example, banding results show that birds from Hawke's Bay rivers mostly move to northern New Zealand, to estuaries and harbours from the Bay of Plenty through to Auckland and Northland; and birds breeding in the Mackenzie Basin mostly migrate to Tasmania and southeast Australia Banded dotterel is a threatened species, considered to be in decline due to the ongoing impacts of terrestrial predators such as cats, mustelids, rats and hedgehogs. It is listed as Nationally Vulnerable as it is considered to meet the criterion of a population of 5,000-20,000 mature individuals with a predicted decline of 30-70% in three generations. The 'Waterbird Population Estimates' (WPE) online database 30 provides a considerably higher estimate for the species, at 50,000 birds, but is estimated from papers published in The banded dotterel population on the lower Ngaruroro has been surveyed on six occasions between 1962 and 1993, and most recently in The number of banded dotterels varied between 246+ and 570 birds during the early surveys (see Table 2). Stephenson surveyed a 12-kilometre section of the river in 2010, and counted a similar number of dotterel within the same section compared to the 1984 and 1993 surveys 32. However, the 2018 survey found 1,101 banded dotterels, twice the number of birds as any previous count. 52 The 2018 count was undertaken by two to three observers where river sections were particularly wide, which is the recommended method for surveying wide braided rivers 33, such as the Ngaruroro. It appears that only single observers were used in the historical surveys, which is likely to be largely responsible for the large increase in banded dotterel counts which are very hard to see from a significant distance. The 2018 count is therefore a much more accurate account of the waterbird population of the lower Ngaruroro River Pierce R. 1999: Regional patterns of migration in the banded dotterel (Charadrius bicinctus bicinctus). Notornis 46: This database provides current and historic estimates, trends and 1% thresholds for over 800 waterbird species and 2,300 biogeographic populations worldwide, in part to support the work of the Ramsar Convention. Wetlands International (2017). "Waterbird Population Estimates". Retrieved from wpe.wetlands.org on Friday 22 Sep 2017 Stephenson B.M 2010: Final report baseline study and assessment of effects on braided riverbed bird communities. Unpublished report, Eco-Vista Photography & Research Ltd. 59p. O'Donnell C.F.J. and Moore S.G.M. 1983: The wildlife and conservation of braided river systems in Canterbury. Fauna Survey Unit Report No. 33, NZ Wildlife Service, Department of Internal Affairs page 14

16 53 Using the more recent estimate of a maximum of 20,000 mature individuals, and the most recent count of 1,101 birds, the lower Ngaruroro holds approximately 5.6% of the national population. Using the WPE estimate, the river's population is approximately 2.2%. Table 3: Summary of selected banded dotterel counts from Hawke's Bay and other New Zealand rivers River Years of Survey Hawke's Bay Ngaruroro 1962, 1984, 2018 Survey Length (km) Mean Count of Banded Dotterel (standard deviation) Mean Number of Banded Dotterel per Kilometre (standard deviation) (362.8) 14.0 (7.4) 2018 only 49 1, Tutaekuri 1962, 1967, (84.8) 6.6 (2.1) 1972, 1984 Tukituki 1967, 1972, (335.9) 4.1 (2.3) 1984 Wairarapa Wairarapa rivers (11 rivers) 2017 only Range Overall mean 34.4 (53.9) Overall mean 1.8 (2.6) Wellington/Kapiti Otaki , 2014 Canterbury Upper Rangitata 2008, 2010, (14.0) 2.9 (1.2) (116.5) 14.1 (5.8) Lower Rangitata 2007, (3.5) 1.4 (0.1) Lower Waimakariri 2007, 2008, 2009 Lower Rakaia 2006, 2007, 2009 Lower Hurunui 2008, 2009, 2010 Upper Waitaki Range Range of Basin (11 rivers) minimum counts (131.9) 9.6 (3.3) (80.3) 5.9 (1.9) (22.1) 3.0 (0.3) 14.4 (10.5) based on minimum counts 54 Table 3 provides some context with which to assess the relative importance of the Ngaruroro River for banded dotterel. The table summarises count data from a number of rivers throughout New Zealand for more than one year where possible (as counts can vary markedly between years) 34. I have attempted to include 34 Hawke's Bay counts are from Parrish (1998) and include all raw data available within the report, and unpublished Department of Conservation data from Canterbury counts are unpublished Department of Conservation data; years included are those held by myself for previous research. Wairarapa and Otaki counts are from McArthur N. and Burgin D 2017: Wairarapa river bird surveys project Regional summary report. Client report prepared for Great Wellington Regional Council, Wildlife Management International Ltd, Blenheim, and McArthur N., Small D. and Govella S. 2015: Baseline monitoring of the birds of the Ōtaki, Waikanae and Hutt Rivers, Greater Wellington Regional Council, Publication No. GW/ESCI-T-15/42, Wellington. Waitaki Basin data taken from Maloney R.F., Rebergen A.L., Nilsson R.J. and Wells N.J., 1997: Bird density and diversity, in braided river beds in the Upper Waitaki Basin, South Island, New Zealand. Notornis 44: page 15

17 known and potentially important braided rivers for avifauna from around New Zealand, including rivers with Water Conservation Orders such as the Rakaia and Rangitata. I could not find any data for the Rangitikei River, the fourth largest of the North Island's braided rivers (despite communications with several knowledgeable people). The table shows the mean count and the mean number of banded dotterel per kilometre. This latter measure does not take into account the width of the rivers which can vary significantly. 55 The data above show that the Ngaruroro supports a very large population of banded dotterel, possibly larger than many of the major braided river systems in Canterbury, including the Rakaia and Rangitata, both of which have Water Conservation Orders which recognise outstanding bird habitat values. A survey of the Tukituki/Waipawa River in 1984 recorded 963 banded dotterel; this river clearly also supports a very large population, possibly comparable to the Ngaruroro. 56 Rivers in the Waitaki Basin support particularly dense populations of banded dotterels. Maloney et al. (1997) showed that the largest population was the Tasman River (minimum count of 599 banded dotterel over three years), a river that reaches four kilometres wide in parts. The authors estimated the survey area to be 3,820 hectares in size (including water and vegetated areas), giving a minimum density of 0.16 banded dotterels per hectare. Wilson (2001) estimated the area of the lower Ngaruroro to be 3,501 hectares, giving a density of 0.31 banded dotterels per hectare (based on the data in Table 3), suggesting the Ngaruroro may support higher densities of banded dotterels (acknowledging different methods of analysis and different years of survey). 57 The reasons for the extraordinary size of the lower Ngaruroro banded dotterel population are worthy of investigation. It is likely to be the result of a combination of factors that could include: the availability of extensive breeding habitat, an extended breeding season in the north of New Zealand, different flood regimes (i.e. less floods during the breeding season), long term clearance of weeds using root raking leading to greater habitat availability and less cover for terrestrial predators, and abundant food sources such as invertebrates and fish. 58 In summary, the numbers of banded dotterel counted in 2018 (1,101 birds) may be one of the largest populations ever recorded on a river in New Zealand in recent years. Further, the population on the lower Ngaruroro represents more than 5% of the national population. These findings clearly demonstrate the outstanding bird habitats of the lower Ngaruroro for banded dotterel. South Island pied oystercatcher (At Risk-Declining) 59 South Island pied oystercatcher (Haematopus finschi) is an endemic species that breeds in the South Island. Birds mostly breed on inland riverbeds or pasture, but page 16

18 also nest in coastal areas, usually close to estuaries or lagoons. After breeding, South Island pied oystercatchers migrate to coastal areas throughout the North and South Islands. Population trends have changed markedly over the decades. The species was hunted by people until it was protected from shooting in 1940, at which point it probably numbered less than 10,000 birds. What happened next was described as a "spectacular irruption" of numbers. By , the population numbered 49,000 birds, and by , it had further increased to 112,000 birds, estimated from national wader counts. However, it then appears to have declined back to 1980s levels, and is still considered to be in decline The Ngaruroro River stands out in the North Island as being one of two locations where South Island pied oystercatcher have been recorded breeding since the 1980s. It is not known whether the second location, Lake Onoke, Wairarapa, is still used by pied oystercatchers. In contrast, the Ngaruroro supports a regular breeding population. The 2018 survey indicates that the population may have increased substantially from previous years (the species is a much larger bird than the banded dotterel, and counts will not be as adversely affected by a single observer undertaking surveys). 61 Clearly, the Ngaruroro River does not meet the 1% of 5% thresholds for this relatively numerous species. However, the river is very unusual in that it supports the only known population of breeding South Island pied oystercatcher in the North Island. In my opinion, this adds to the outstanding nature of the bird habitats of the lower Ngaruroro. Black-fronted dotterel (At Risk-Naturally Uncommon) 62 Black-fronted dotterel (Elseyornis melanops) is a relatively recent coloniser from Australia. In Australia, it is widespread, normally inhabiting non-tidal freshwater wetlands, but often migrating to the coast during inland dry periods. A recent analysis of 30 years of Australian shorebird monitoring data indicates that the species is in decline around coastal Australia, thought to be due to degradation of wetlands in Australia's interior (in particular, lower water levels) Black-fronted dotterel was first observed in New Zealand in 1954 at the Ahuriri Estuary in Napier. Several more sightings were recorded over the following years. In 1961, breeding was recorded for the first time a few years later with a total of 13 adults and nine juveniles observed on the Tutaekuri and Ngaruroro Rivers Sagar, P. & Veitch, D Conservation assessment of the South Island oystercatcher Haematopus finschi. International Wader Studies 20: Clemens R., Rogers D.I., Hansen B.D., Gosbell K., Minton C.D., Straw P., Bamford M., Woehler E.J., Milton D.A., Weston M.A. and Venables B., 2016: Continental-scale decreases in shorebird populations in Australia. Emu-Austral Ornithology, 116: page 17

19 Hawke's Bay riverbeds were formally searched during the breeding season of 1962, and 109 birds were located 37. Since then, the breeding distribution has extended to the southern North Island, north-east South Island, Canterbury, Otago and Southland 38. The national population appears to be increasing slowly. 64 On the Ngaruroro, counts demonstrate the establishment of the black-fronted dotterel; birds, birds, birds, birds, birds. In November 2018, 217 birds were counted (200 were counted within the length of river surveyed in previous years). It is not clear whether this is an actual increase, or due to the more intensive survey method, or a combination of the two. 65 The population size as provided in the international Waterbird Population Estimates database is 1,700 birds 39. Heather and Robertson (2005) describe the regional breakdown of this total as follows: Hawke's Bay 800, Wairarapa 300, Manawatu 300, Marlborough 50, Canterbury 150, Otago 50, and Southland In comparison, a recent survey of 11 Wairarapa rivers recorded a total of 514 black-fronted dotterel, considerably more than the previous estimate of 300 birds in the Wairarapa. This suggests that the total population estimate of 1,700 birds may now be out of date. Most recently, Armitage states that the New Zealand population numbers fewer than 3,000 birds 41. Using the estimate of 1,700 birds, the Ngaruroro population supports 11.8% of the national population. Using a maximum number of 3,000 birds, the river holds an estimated 6.7% of the national population. 67 The largest population of black-fronted dotterel in New Zealand may be on the Tukituki, where 368 birds were recorded in 1984 (c.f birds on the Ngaruroro at the same period), but there are no recent counts. Much more recently, the 2017 Wairarapa river surveys reported a population of 192 birds over 82 kilometres of the Ruamahanga River, suggesting this river also supports a nationally significant population. No other significant North Island populations were identified, though the lack of survey of the Rangitikei, one of the largest Habraken T. 1996: Black-fronted dotterel breeding near Rotorua. New Zealand Wader Study Group. Newsletter 7: p5. Gill B., Bell B.D., Chambers G.K., Medway D.G., Palma R.L., Scofield R.P., Tennyson A.J.D. and Worthy T.H. 2010: Checklist of the birds of New Zealand. Ornithological Society of New Zealand. Wetlands International (2018). "Waterbird Population Estimates". Retrieved from wpe.wetlands.org on 27 Nov Heather B. and Robertson H. 2005: The field guide to the birds of New Zealand. Revised Edition. Armitage I [updated 2017]: Black-fronted dotterel. In Miskelly C.M. (ed.) New Zealand Birds Online page 18

20 braided rivers in the North Island, is a significant information gap. Numbers of black-fronted dotterels in the South Island remain very low. 68 In summary, the lower Ngaruroro supports the largest known population of blackfronted dotterel in New Zealand, although it is likely that the Tukituki supports a greater number. Numbers exceed 5% of the national population, further demonstrating the outstanding bird habitats of the lower Ngaruroro. Australasian bittern (Threatened-Nationally Critical) 69 Australasian bittern (Botaurus poiciloptilus) is one of New Zealand's rarest and most threatened bird species, recently upgraded to Nationally Critical. Australasian bittern is a wetland specialist, and its decline is most likely tied in to the massive loss of wetlands throughout New Zealand over the last century, but also possibly introduced predators. Recent research suggests winter starvation may be a significant issue facing the species 42. The species is also found in Australia and New Caledonia, where it is equally threatened. The population size as provided in the international Waterbird Population Estimates database is 1,000-1,500 birds, with a 1% threshold of 10 birds (even lower in Australia) 43. This is supported by the species' most recent threat classification which assumes the species to have a maximum population size of 1,000 mature individuals. 70 On the Ngaruroro River, bittern have been recorded several times from Pigsty Wetland, a tributary of the lower Ngaruroro, and are regularly observed at Waitangi Estuary, as well as other adjacent wetlands such as Lake Runanga. Tracking studies have shown that bittern use networks of wetlands many kilometres apart; birds using the Ngaruroro River are likely to also use other wetlands in the area. Stephenson undertook a helicopter survey of the river in 2009 and considered the river section between Whanawhana to Mangatahi to support considerable potential bittern habitat; he recorded an observation of a probable bittern in the river's riparian margins at Ohiti at much the same time. 71 An extraordinary photograph was taken by a local bird watcher of three Australasian bittern, a white heron (Nationally Critical; 1% threshold = 1 bird), and a white-faced heron (Not Threatened) at Waitangi Estuary in Williams E [updated 2018]: Australasian bittern. In Miskelly, C.M. (ed.) New Zealand Birds Online. Wetlands International (2018). "Waterbird Population Estimates". Retrieved from wpe.wetlands.org on 27 Nov The photograph can be found associated with this text: page 19

21 72 John Cheyne, who has undertaken and assisted with bittern research in the North Island, including Hawke's Bay, has observed up to five bittern on a single occasion within the Horseshoe Wetland at the estuary, and considers the population in the Ngaruroro catchment to number 6-8 booming males, mostly on Lakes Runanga and Oingo on the northern side of the lower Ngaruroro (J. Cheyne pers. comm. December 2018). 73 It is possible that the wider wetland network of the lower Ngaruroro, combined with the lower Ngaruroro River itself and its estuary, support 10 or more bittern (the 1% threshold); few locations in New Zealand appear to support such numbers 45. In my opinion, the presence of a breeding population of bittern in the wider Ngaruroro area that uses the lower river significantly raises the national importance of the Ngaruroro, whether or not it meets the 1% threshold. I strongly recommend that intensive survey of the river and adjacent wetlands is undertaken to better understand the population size and habitat use of bittern in the area, and to allow management actions to be determined to secure the population's survival in the region. Pied stilt (Not Threatened) 74 Pied stilt (or black-winged stilt as it is known overseas) is found throughout much of the world. The New Zealand subspecies, Himantopus himantopus leucocephalus is also found in Australia and the Philippines. It is thought be a relatively recent arrival to New Zealand. The species was listed as At Risk- Declining in the 2012 iteration of threat classifications for birds 46, but was downgraded to Not Threatened in The population was estimated at a minimum of 30,000 birds in 1996 using nationwide non-breeding counts 47. The international Waterbird Population Estimates database still uses this estimate. 75 The 2018 survey on the lower Ngaruroro detected 559 pied stilt, or 1.9% of the national population, making the river nationally significant for this species. 76 In comparison, the 2017 surveys of the 11 Wairarapa rivers found a total of 317 pied stilt over all the rivers. In Canterbury, the maximum number recorded on the lower Rangitata over four surveys from was 247; the maximum number recorded on the upper Rangitata over three surveys from was 39; the maximum number recorded on the lower Rakaia over three surveys from O'Donnell C.F.J. and Robertson H.A. 2016: Changes in the status and distribution of Australasian bittern (Botaurus poiciloptilus) in New Zealand, 1800s Notornis 63: Robertson, H.A.; Dowding, J.E.; Elliott, G.P.; Hitchmough, R.A.; Miskelly, C.M.; O'Donnell, C.F.J.; Powlesland, R.G.; Sagar, P.M.; Scofeld, R.P.; Taylor, G.A. 2013: Conservation status of New Zealand birds, New Zealand Threat Classification Series 4. Department of Conservation, Wellington. 22 p. Sagar et al page 20