Tane 37: 69-89 (1999)

HISTORY, F A U N A AND F L O R A O F T E H A U P A (SADDLE) ISLAND, H A U R A K I G U L F

Alan J.D. Tennyson1 and Graeme A. Taylor 2

' M u s e u m o f N e w Zealand Te Papa Tongarewa, P O B o x 467, Wel l ing ton : 5 0 Kinghorne Street, Strathmore, Wel l ing ton (current addresses)

S U M M A R Y

Te Haupa Island was surveyed for plants and animals 11 times between 1987 and 1997. The island has been highly modified by clearance o f the vegetation, including by fire. Twenty native species of bird, including a small colony o f grey-faced petrels (Pterodroma macroptera), and five introduced species were recorded. Norway rats (Rattus norvegicus) were present, but were eradicated in 1989. M i c e (Mus musculus) were present in 1997 and should be removed. A rare land snail (Succinea archeyi) was recorded. The island's vegetation was rapidly regenerating, with pohutukawa (Metrosideros excelsa) forming a near complete canopy over the whole island. The vascular flora consisted o f 124 taxa, 58 % native. N o serious weed species are well-established. The regenerating vegetation remains at risk from fire. Te Haupa is beyond the normal swimming range of rodents. In the future it could be used as a site for transferring rare invertebrates and lizards.

Keywords: Hauraki G u l f island; grey-faced petrel; bird list; plant list; regeneration o f vegetation; rodent eradication; restoration of islands.

I N T R O D U C T I O N

Te Haupa or Saddle Island, is a small (6.0 ha, Taylor 1989) island in the inner Hauraki G u l f ( 3 6 ° 3 1 ' S 174°47 'E) . It lies 950 m off Mahurangi Heads (750 m via an offshore reef)- Te Haupa is 650 m long, but only 50-150 m wide, with its long axis lying north-south. The southern and northern ends o f the island are 33-35 m above sea level and there is a low central saddle (Fig. 1). On the western shore there is a large, sandy beach and above this sand dunes that are largely covered by vegetation (Fig. 2). Steep cliffs surround the remainder of the island, particularly on the more exposed eastern side, and beyond this, an intertidal rock platform extends about 100 m out to sea (Figs. 3 & 4). To the north there is a section of wave platform which is separated from the main reef by 100 m. We refer to this as the northern reef. There is no source of permanent

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freshwater. Te Haupa is composed of early Miocene mudstone, being part of the Waitemata formation, which also composes the adjacent mainland ( B . W . Hayward in litt. to E . K . Cameron, 1998). The well-bedded layers dip about 10° to the south-west. Vis i tors regularly camp on the low saddle under large pohutukawa {Metrosideros excelsa) trees and there are several (illegal) fires sites (Fig. 5).

Eleven visits were made to Te Haupa between 1987 and 1997, primarily to survey the island's petrels and vascular plants and to clarify the status o f introduced mammals. Trip times, dates and personnel were: 1245-1545 hrs on 19 August 1987 (Tim Lovegrove, G T ) ; 1100-1400 hrs on 23 August 1987 (John Dowding , T i m Lovegrove, Sandy Taylor, G T ) ; 1300 hrs on 2 June to the morning o f 3 June 1988 (Ian McFadden, G T ) ; 45 minutes near midday on 31 July 1988 (Sandy Taylor, G T , A T ) ; 0900-0940 hrs on 16 October 1988 (Sandy Taylor, A T , G T ) ; briefly on the afternoon o f 25 February 1989 (Phil Battley, Paul Scofield, A T , G T ) ; 45 minutes in the afternoon on 1 March 1989 (GT, A T ) ; 1050-1250 hrs on 28 June 1989 (GT, A T ) ; 1700 hrs on 7 M a y to 1100 hrs on 8 M a y 1990 (Geordie Murman, Paul Scofield, Gwenda Pulham, A T ) ; 1730 hrs on 24 August to 0945 hrs on 25 August 1990 (Gwenda Pulham, Graeme Saunders, A T ) ; 1030 hrs on 30 August to 1645 hrs on 31 August 1997 (Gwenda Pulham, Andrea Booth, A T ) . A l l times are New Zealand standard time.

Bi rd species only seen flying wel l offshore or washed up on beaches are not included in this article, but all beached bird records were submitted to the Ornithological Society's Beach Patrol Scheme. B r i e f notes on archaeological sites, lower plants and invertebrates are also presented.

HISTORY

Files on Te Haupa (NP35, V o l s 1 & 2) in the Auck land Department o f Conservation (DoC) office and the Conservation Management Strategy (DoC 1995) provided some information on the island's history. Mar ie A lpe helped clarify some o f this and Robert Brassey supplemented it by providing some pre-20th century information via Ewen Cameron (pers. comm., 1998).

Te Haupa is named after an important Nga t i Paoa chief, who slew Tarahawaiki o f Te Taou because of an insult. A feud followed with many decades o f battles involving tribes from the Bay o f Islands to Cook Strait. A n 1834 map, drawn during the HMS Buffalo visit, shows the island as Motou Whora, an 1836 chart has it as Whora Is., and an 1891 naval chart shows it as Horora. These three names are presumably incorrect, being based on the name of the larger nearby island Motuora, although the latter two maps also show Motuora named correctly.

In about 1945, most of the vegetation on Te Haupa was burnt and only a few old pohutukawa survived (G. Anderson pers. comm., 1990).

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Fig. 4. Northern coast of Te Haupa, showing extensive intertidal rock platform, 30 August

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Fig. 5. Campsite, Te Haupa, 8 May 1990.

In 1947, action was taken by the Commissioner o f Crown Lands office to have Te Haupa constituted a Domain, with control vested in the Rodney County Counci l , but the matter was not proceeded with at the time. On 13 August 1951 the Commissioner's office approached the Counci l again and asked whether the Counci l would still be interested in taking over control of the island i f it were made a public domain. On 5 December 1951, the area was declared a Recreation Reserve vested in the Casnall Island Domain Board as an addition to the Casnall Island Domain ( N Z Gazette 6 December 1951: 1785, N Z Herald 28 November 1968: 5) [Casnall Island is a small island 2.5 km away in Mahurangi Harbour - see de Lange & Crowcroft (1996) for an account o f its flora.]

On 3 June 1954, Vernon Wheatley o f M i l f o r d , Auck land , wrote to the Department of Crown Lands, Auckland, wanting to lease Te Haupa and set up his home there: "I propose to grow pumpkins, marrows and desert melons for the Auck land market ... From the onset, I would also make attempts in the cultivation of sub-tropical fruits and berries ... the area would be kept by me as a bird sanctuary ... The island has never, to my knowledge, been inhabited and it is uninhabited now. A t present, the island is in grass, and there are a few clumps of small trees on it. These would not be disturbed; indeed, they would be added to". Evidently, M r Wheatley did not take up residence there - presumably his proposal was rejected.

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In A p r i l 1967, the 'Doma in ' was bought from the Rodney County Counci l for the Hauraki G u l f Mari t ime Park ( H G M P ) , under control o f the Park's board. It was added to the Park on 26 November 1968 ( N Z Gazette 28 November 1968 No.78: 2202). In 1967 it was recorded as having a capital value of $17,000.

O n 26 July 1970, W a l l y Sanders (Ch ie f Ranger) made an "Inspection Report" on the island: " W e spent only a short time on this Island but were impressed with the very good beach. There are also some petrel burrows and these need further investigation to decide whether some form of protection is required. Ranger Fisher w i l l also carry out periodic patrols to find out what type of use it is receiving and to assess the need for any amenities".

On 26 November 1973, Te Haupa was re-gazetted as a Recreation Reserve ( N Z Gazette 6 December 1973 N o . l 15: 2690) as part o f an administrative tidy up due to its control changing from the County Counci l to the H G M P Board.

In 1978, greater than two cables of sand was removed from the seabed off Te Haupa by dredging. Earlier extensive dredging (for shingle) also occurred off the nearby Moturekareka Island group (Tennyson et al. 1997).

A n inspection was made by reserves rangers P. Green (chief ranger in Auckland), M . Sharp (ranger at North Head), C . Clark (ranger at Auckland) and S. Murre l l (publicity officer) in A p r i l 1980. They produced a rather superficial and inaccurate 'Reserve Report ' (dated 2 July 1980) that was dismissive o f the island's natural values, i.e. " N o outstanding features ... N o reported or known noteworthy archaeological, historical, geological, soi l , etc features, N o records of native bats, frogs, lizards, f/w fish, native land snails or invertebrates o f interest ... very little birdlife" and "few resident birds". Whi le noting that " N o botanical report has yet been undertaken", they described the native vegetation cover as "predominantly karo [Pittosporum crassifolium] wi th manuka [Leptospermum scoparium], mahoe [Melicytus ramiflorus], pohutukawa and various coprosmas", that "There is a little gorse [Ulex europaeus] holding the c l i f f faces together", but that there is " N o planting of exotics or native plants". They note that "The island is severely threatened by fire" and recommend a long term consideration of " N o camping".

On 17 December 1980, Te Haupa, previously a Recreation Reserve under the H G M P Board, was re-classified as a Scenic Reserve along with Casnell Island ( N Z Gazette 15 January 1981 N o . l : 23). A Scenic Reserve is established for scenic and biological protection, freedom of access and conservation of natural qualities.

A survey was made by P. & S. Thomson and R. Chappell for the H G M P from 1100-1300 hrs on 7 December 1981. P. Thomson's report noted " M a o r i diggings", a "Pohutukawa canopy" and a "small grassy area near camp sites", " N o definite sign o f fires" and "Rats common, no cats". He also listed six species of bird present.

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In 1984, an application, under the Marine Farming Act , for a 22 ha marine mussel farm to the east of Te Haupa was made by P . G . Nutsford et al. to the Chair o f the H G M P Board. O n 16 January 1985, G . E . Rowan wrote to the Director General o f the Minis t ry o f Agriculture and Fisheries, Auck land , on behalf o f the Board and objected to the proposal for a marine farming licence. The letter notes: "Almost the whole area of the island is covered in a mantle of coastal bush which contains some remarkable specimens o f both very o ld pohutukawa, karo and kowhai [Sophora microphylla] trees".

Management o f Te Haupa passed from the H G M P Board to D o C , with its formation in 1987. In 1995 D o C published its A u c k l a n d Conservancy Conservation Management Plan, giving an outline of the island's legal status, physical description, history, flora and fauna (DoC 1995). A partly inaccurate list o f birds, predominant plants and introduced animals was provided.

F A U N A

Birds * = introduced species

Grey-faced petrel/oi {Pterodroma macroptera) - petrel burrows were first noted in Sanders' 1970 report, however the recommendation for further work to see whether any protection for the birds was required, seems not to have been implemented. Thomson's 1981 report noted petrel burrows thought to be of this species.

During our visits we searched the entire island carefully for burrows and found a maximum of 24 active burrows in one season (1997). Petrels were surveyed by ground searching for burrows and by the "war-whoop" technique (see Tennyson & Taylor 1990). Although we mapped a total of 33 burrows over the ten year period o f our survey, nine had eroded away or were fi l led in by 1997 while during the same period new ones had been dug. Three burrows were found at the top o f the bank at the northern end o f the island, one was on the north-eastern c l i f f top, 12 were along the south-eastern c l i f f top and 17 were on banks above the south-western coast.

It was not clear how many of the burrows were used by grey-faced petrels because some were too long to determine their contents and penguins often used burrows on the island also (five burrows were recorded being used by both petrels and penguins). Nevertheless, 13 different burrows were confirmed as having grey-faced petrels present at least once. Fifteen adult petrels were banded at burrows. We estimate that only 5-15 pairs attempted to nest each season during 1987-97. There was no clear difference between the number of petrels nesting in 1987-90 and in 1997.

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Petrels were recorded incubating eggs on 28 June 1989, 31 July 1988, 19 August 1987, 24 August 1990 and 30-31 August 1997. On 16 October 1988, no petrels were found ashore in the 12 burrows checked but at least four o f these burrows had egg shell fragments scattered outside and two contained penguins. A t this time of year there should have been chicks in burrows (Imber 1976), so apparently there had been total breeding failure on the island.

There was a considerable amount o f non-breeding petrel activity during the early part of the breeding season. We caught several birds that were not clearly associated with burrows, mostly using the "war-whoop" technique. On 7 M a y 1990, we landed all eight birds heard calling in flight using "war-whooping". A t night on 24 August 1990, we noted up to five petrels aerial chasing and caught nine birds not clearly associated with burrows. On 30 August 1997, three "war-whoop" responding birds were caught at night. One o f the petrels banded on 7 M a y 1990 ( E - l 13752) was recaptured 45 km to the north-east on Little Barrier Island by Terry Greene on 14 M a y 1993 when he was "war whooping". This indicates that non-breeding birds were moving between colonies in the Hauraki Gulf.

Blue penguin/korora (Eudyptula minor) - Thomson's 1981 report is the first to note breeding penguins.

A s with the petrels, it was difficult to determine exactly how many penguins nested on Te Haupa. Some burrows were used by petrels also and it was difficult to estimate how many penguins were nesting amongst coastal rocks. A t least eight different burrows were confirmed as having penguins present at least once. The highest numbers recorded on single visits were: on 23 August 1987 when at least six burrows containing penguins were found plus one broken egg was found in a cave; on 30-31 August 1997 when 4-7 penguin burrows were found, penguin bones were found in another burrow and another active site was found amongst coastal rocks. Penguins were also recorded ashore on 2 June 1988, 16 October 1988, 28 June 1989, 7 May 1990 and 24-25 August 1990. A few penguin burrows above the south-western coast were probably not found because they would have been hidden under thick vegetation. N o more than two nests in rocky coastal sites were recorded on any trip. We estimate that only 5-15 pairs attempted to nest each year between 1987-97.

Black shag/kawau (Phalacrocorax carbo) - single birds flew past Te Haupa on 1 March 1989 and 31 August 1997.

Pied shag/karuhiruhi (Phalacrocorax varius) - one roosted on 19 August 1987. Two on 31 August 1997.

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Little shag/kawaupaka (Phalacrocorax melanoleucos) - one on 23 August 1987 and 28 June 1989, two on 30 August 1997.

Reef heron/matuku-moana (Egretta sacra) - one on 24-25 August 1990 and one on the northern reef on 30 August 1997.

Paradise shelduck/putangitangi (Tadorna variegata) - one pair flew over on 30 August 1997.

Australasian harrier/kahu (Circus approximans) - one flew out from the mainland to Te Haupa on 1 March 1989.

Variable oystercatcher/torea (Haematopus unicolor) - noted on five of our visits, with a maximum of about eight on 30-31 August 1997. Oystercatchers have nested here (G. Anderson pers. comm., 1990).

New Zealand dotterel/tuturiwhatu (Charadrius obscurus) - one on the northern wave platform on 31 August 1997.

Southern black-backed gull/kororo (Larus dominicanus) - the Conservation Management Strategy (DoC 1995) records this species as present on Te Haupa. Small numbers were seen on most of our visits, with a maximum of 14 on 28 June 1989.

Red-billed gull/tarapunga (Larus novaehollandiae) - the Conservation Management Strategy (DoC 1995) records this species as present on Te Haupa. On 28 June 1989, 25 were seen on rocks. Heard calling at night on 7 M a y 1990. One noted on 30-31 August 1997.

White-fronted tern/tara (Sterna striata) - the Conservation Management Strategy (DoC 1995) records this species as present on Te Haupa. On 1 March 1989, we noted 78, including 15 juveniles. On 31 August 1997, seven were on the northern reef. The reserves ranger's 1980 report noted that the island could be an ideal nesting area for terns "which nest on sand", however, the entire rocky shoreline platform and beach are regularly washed by high tides.

Morepork/ruru (Ninox novaeseelandiae) - Thomson's 1981 report noted the presence of this species. On 28 June 1989, one was seen. Single birds were heard calling at night on 7 May and 24 August 1990.

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Kingfisher/kotare (Halcyon sancta) - Thomson's 1981 report and the D o C Conservation Management Strategy noted the presence o f this species. We recorded it on six visits, with maximums of four on 28 June 1989 and a few on 30-31 August 1997.

Welcome swallow (Hirundo tahitica) - one or two were present on 19 August 1987. One that flew out from an overhanging ledge on the eastern c l i f f on 16 October 1988 could have been on a nest. Five were seen on 16 October 1988 and two on 30-31 August 1997.

*Blackbird (Turdus merula) - small numbers, usually singles, noted on most o f our visits. On 30-31 August 1997, we recorded a few birds and two old nests.

Grey warbler/riroriro (Gerygone igata) - both the reserve ranger's 1980 report and Thomson's 1981 report noted the presence o f this species. It was the most common land bird during our visits, with several recorded on most trips.

Fantail/piwakawaka (Rhipidura fuliginosa) - one heard on 31 July 1988 and a few on 30-31 August 1997.

Silvereye/tauhou (Zosterops lateralis) - we recorded several on most visits.

Tui (Prosthemadera novaeseelandiae) - Thomson's 1981 report notes that this species was common but we only recorded a few on 19 August 1987, apparently feeding from karo flowers, and two on 30-31 August 1997.

*Chaffinch (Fringilla coelebs) - one noted on 16 October 1988 and one or two on 31 August 1997.

*Greenfinch (Carduelis chloris) - one noted on 28 June 1989.

*Goldfinch (Carduelis carduelis) - two seen on 23 A u g 1987 and at least three on 16 October 1988.

*Starling (Sturnus vulgaris) - one noted on 23 August 1987.

The Conservation Management Strategy (DoC 1995) for Te Haupa listed the fauna as "Fluttering shearwater [Puffinus gavia], black and white-fronted shag, white-fronted tern, red bil led and black backed gulls, oystercatchers, kingfisher". There are no records o f fluttering shearwaters ashore on Te Haupa. This record probably results from confusion with the colony on Saddle Island off Great

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Barrier Island (Bel l & Brathwaite 1964). The shag and oystercatcher records aren't clearly enough described to allow species identification.

Archaeological sites and sub-fossil bones The reserve ranger's 1980 report stated that there were no reported or known

archaeological features on Te Haupa, but Thomson's 1981 report notes " M a o r i diggings" and we found an eroding midden in a sand bank on the western, inshore, side of Te Haupa (now N Z A A metric site number R l 0/726). Shells and a few fish, bird and mammal bones regularly erode from this bank and fall onto the beach where they are swept away by the sea. On several visits, we checked this site for sub-fossil bones. On 16 March 1992, Robert Brassey visited Te Haupa and found occasional imported oven stones around the coast (see N Z Archaeological Association Site Record Form). He examined the western sand bank and noted:

"1 . Cultural layer exposed for much o f the length of the coastal escarpment at a depth o f 1-2 metres below the terrace surface. The layer is 10-15 cm thick and contains charcoal, fish bone, and occasional shell (white rock snail [Neothais scalaris] noted);

2. Stratigraphically higher lenses o f midden up to 35 cm thick exposed in slumps below the terrace surface. These typically contain pipi [Amphidesma australe], white rock snail, fishbone ... catseye [Lunella smaragda]...mudsnail [Amphibola crenata]. A n oven containing abundant charcoal and fire fractured rock is also exposed".

On a visit in 1998, Robert Brassey (in litt. to E . K . Cameron, 1998) noted "mammal bone and minor greywacke adze manufacturing debitage" in the western sandbank.

In 1997 we examined what appeared to be extensive earthworks at the northern end of the island, consisting o f three knolls surrounded by terraces. Presumably most o f this area was cleared o f vegetation at the time that these earthworks were made. A s large trees now grow throughout this area, presumably the workings date from a period of Maor i occupation.

Shells that we recorded in the western sand bank were: p ip i - the most abundant species, white rock shell, dark rock shell {Haustrum haustorium), Cook ' s turban (Cookia sulcata), cat's eye, black nerita (Nerita melanotragus), queen scallop (Pecten novaezelandiae), blue mussel (Mytilus edulis), cockle (Chione stutchburyi), rock oyster (Crassostrea glomerata) and radiate limpet (Cellana radians). Some burnt shells indicated that this was at least partly a human midden.

On 16 October 1988 a fully ossified humerus o f a Pterodroma petrel was found. A T identified it as Pycroft's petrel (P. pycrofti) based on its length. On 1 March 1989, one black-backed gull tibia and one kaka (Nestor meridionalis) radius and scapular were found. O n 31 August 1997, bones o f blue penguins

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(S.35573: five vertebrae, two femora, one humerus & one mandible), Norway rats (Rattus norvegicus) (S.35577: one part skull , one mandible, one femur) and a rabbit (Oryctolagus cuniculus) (S.35574: part skull) were found. " S " numbers are in the Museum o f New Zealand ( M N Z ) fossil bone collection.

Invertebrates The introduced snail Oxychilus cellarius was abundant and the garden snail

(Helix aspersa) was common. One specimen o f the introduced snail Vallonia excentrica was collected.

Three specimens o f the native land snail Succinea archeyi were collected in 1997. This species was thought to be confined to dry, sandy, grass communities in Northland, but formerly it occurred as far south as Otago and at several North Island sites during an active dune-building phase in the Holocene (Cl imo 1980). The Te Haupa specimens were found on the surface o f the island and their condition suggested that they had died recently ( K . Mahlfe ld pers. comm., 1997). These records therefore represent a considerable southern extension to the known surviving range o f the species. Other native snail species collected were a punctid (Laoma sp.) and Therasia zelandiae. A l l snail specimens are in the M N Z collections.

A few other invertebrates were collected and placed in the M N Z also. These include an introduced Australian ground spider Supunna picta, a native w o l f spider Lycosa hilaris, a cave weta, two scarab beetles ( including Ocnodes brookesi), two shore earwigs (Anisolabis littorea) and some bird lice. A n Asian paper wasp (Polistes chinensis) nest was found in February 1989 and a single wasp of this species was seen in 1997.

Introduced mammals Thomson's 1981 report was the first to note that rats were present on Te

Haupa, but only in 1987 were they identified as Norway rats (Taylor 1989). On 19 August 1987 large rat droppings (10-20 mm long, n = 18) were noted all over the island and numerous small burrows (5-10 cm wide) and shallow digs were common. Twenty four Ezeset rat traps were set 20-25 m apart in pairs, baited with peanut butter. These traps were checked on 23 August 1987. They had caught five Norway rats and the bait was taken from all the other traps. It is not known how long Norway rats had been present on Te Haupa, but they possibly reached the island by boat because this species normally does not swim more than 500-600 m (Taylor 1989). Alternatively, tidal currents from Mahurangi Harbour may have assisted their arrival. Norway rats have colonised The Noises Islands at least three times and are believed to have swum the 2 km from nearby Rakino Island, assisted by sea currents (I. McFadden pers. comm., 1996).

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On 2-3 June 1988, Ian McFadden and G T did some trials o f different flavoured non-toxic Wanganui No.7 cereal baits (Taylor 1989) and also trapped 12 adult Norway rats in the 25 live traps that they set overnight.

On 31 July 1988 we placed about 25 Rid-rat poison baits at 10 m intervals over the central and northern parts o f the island to reduce rat numbers in the hope that this might improve breeding success of the petrels. However, no petrel chicks were noted in October 1988, so evidently our rat control was not very effective. Clear rat sign (rat holes and chewed karo fruit on the ground and footprints in the sand) was present on 25 February and 1 March 1989.

Taylor (1989) stated that the rats "should be poisoned by a ground based [eradication] operation and permanent poison stations maintained on the island". Later in 1989, Rex Gi l f i l l an laid out Talon 5 0 W B poison to eradicate the rats (C.R. Vei tch pers. comm., 1997). On 7-8 M a y and 24-25 August 1990, no evidence o f rodents was found, despite intensive searching for rodent sign, including putting out 31 peanut butter baits overnight. This strongly indicated that Norway rats had been successfully eradicated.

M i c e (Mus musculus) were first recorded on Te Haupa shortly after the Norway Rats were eradicated (C.R. Veitch pers. comm., 1997). Previously they may have been ove r looked i f Norway rats had suppressed their population on the island. Norway rats appear to have a negative effect on mice populations (Taylor 1984). Alternatively, mice may have only established since rats were eliminated in 1989. Colonisat ion would have been much easier without competition for food with the rats, which may also prey upon mice (Moors 1990). Undoubtedly mice reached Te Haupa by being transported by people, as mice can not swim water gaps more than 50-100 m wide (Taylor 1989).

On a visit on 16 March 1992, Robert Brassey (in litt. to Ewen Cameron, 1998) noted rodent-gnawed karo fruit presumably this was caused by mice. On 30 August 1997, A T set seven mouse snap traps, one rat snap trap and laid out 20 non-toxic cheese baits. That night several mice were seen. In the morning all the baits on the traps and the ground were gone, three mice were caught in mouse traps and one was caught in the rat trap. These mice were deposited in the Auckland Museum collection.

Al though the D o C (1995) Conservation Management Plan states that Norway rats are present on Te Haupa, we believe that this statement was based on out-of-date information.

The rabbit bone found on Te Haupa is o f interest because it suggests that rabbits could have been l iv ing on Te Haupa in the past. This would not be unlikely because rabbits occur (or formerly occurred) on several islands in northern New Zealand (Taylor 1989, Gibb & Wi l l i ams 1990). Alternatively, people could have brought out a rabbit carcass to eat and left the remains behind or possibly a harrier or black-backed gull carried part of a corpse there from the mainland.

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F L O R A

Pohutukawa up to 20 m high forms a near complete canopy over the whole island. In the past, much of Te Haupa has been cleared of trees but evidently some large trees survived the burning which occurred in about 1945 and probably at other times. Karo was abundant in the subcanopy and coastal karamu (Coprosma macrocarpa) dominated the shrub layer. There was a full range o f karo size classes in the understory, including numerous seedlings and saplings. Mahoe and ming iming i (Leucopogon fasciculatus) were fair ly common in the southern half of the island. A t least a dozen totara (Podocarpus totara) seedlings and saplings were scattered across the island. The tallest was 4 m high in 1997. Gorse covered exposed c l i f f sites and headlands, but was absent from forest interiors. Ground cover under forest was dominated on different parts o f the island by Doodia australis, Oplismenus imbecillis, Phymatosorus pustulatus and knobbly sedge (Isolepis nodosa). Clearings were present in the central portion o f the island. Knobbly sedge and N e w Zealand flax (Phormium tenax) were common in these clearings. Pohuehue (Muehlenbeckia complexa) and bracken (Pteridium esculentum) patches also dominated some clearings. Dominant grasses included cocksfoot (Dactylis glomerata), Microlaena stipoides, ratstail (Sporobolus africanus), sweet vernal (Anthoxanthum odoratum) and Lachnagrostis filiformis. Lagurus ovata was local ly common on sandy slopes and ripgut brome (Bromus diandrus) was seasonally common.

Small herbaceous plants also thrived on the open sandy soils. K i n g Island melilot (Melilotus indicus) was very common in clearings and vetch (Vicia spp.), fleabane (Conzya albida), Lotus suaveolens, Leontodon taraxacoides and Medicago polymorpha were also common.

We have no records o f manuka on Te Haupa, despite the 1980 reserve ranger's report stating that it was one of the predominant tree species. A l s o , we have no records of kowhai on the island, despite the H G M P Board's 1985 letter noting the presence of "some remarkable specimens of . . . kowhai trees" and its listing in the Conservation Management Strategy as a "predominant" species (DoC 1995). Nor do we have records of karaka (Corynocarpus laevigatus), which was noted in 1992 (see N Z Archaeological Associat ion Site Record Fo rm) . W e presume that these records are based on errors and misidentifications.

The only planted species were two exotic succulents (Aeonium haworthii and Kalanchoe cultivar) which were confined to a small patch above the main path up from the beach near the centre of the western shoreline in 1997. These had probably been planted recently as they had not spread far. A l l specimens found

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were removed. Brassey noted that Cannabis sativa had been planted at the southern end of Te Haupa during the 1990s, but we found no sign of it.

We recorded 124 vascular plant taxa on Te Haupa, including 13 ferns, 1 gymnosperm, 78 dicotyledons and 32 monocotyledons (Table 1). Seventy-two (58 %) o f these taxa are native. Abundance for each taxon is noted (see key). W e also collected a few o f the more obvious non-vascular plant species (Table 2). Where a voucher specimen exists to support the record, the herbarium sheet is listed. Vouchers were deposited in the A K U (Auckland Universi ty), A K (Auckland Museum) or W E L T ( M N Z ) collections.

Table 1. Vascular Plant List for Te Haupa Island

K e y * = adventive species, a = abundant, c = common , o = occasional , 1 = loca l , s = scarce (< five individuals seen), P = planted

Scientific Names Abundance (and voucher specimens)

Ferns (13 + 0) (= native + adventive totals) Adiantum cunninghamii Asplenium haurakiense A. oblongifolium Blechnum filiforme Cyathea dealbata C. medullaris

Doodia australis Pellaea rotundifolia Phymatosorus pustulatus Polystichum richardii Pteridium esculentum Pteris tremula Pyrossia eleagnifolia

o (but not seen 1997) o (1987-90), s (2 plants 1997) o (only dead plants: 12 on 2/6/88, 2 at S end in 1997) la s o(1987-90) , la (1997) o c I c

Gymnosperms ( 1 + 0 ) Podocarpus totara o (largest 4 m in 1997)

Dicotyledons (40 i 38) Aeonium haworthii* Anagallis arvensis* Apium prostratum s.str. Aster subulatus* A triplex prostrata* Brachyglottis repanda Cakile maritima*

Calystegia soldanella Carmichaelia australis

P (1 smal l patch in 1997, removed) o s s 0

s lc (not seen 1997 - possibly washed away) s o (at S end) A K 233754

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Centaurium erythraea* 0

Cerastium glomeratum* 0

Chrysanthemoides monilifera* s (only seen 28/6/89) Cirsium vulgare* 0 Clematis paniculata s (1 male S end 1997) A K 233753 Conyza albida* c Coprosma areolata s C. macrocarpa a C. macrocarpa x C. propinqua s C. macrocarpa x C. robusta c C. robusta s C. repens s C. rhamnoides 0 Crepis capillar is* o A K 233750 Dichondra repens o (1987-90), lc (1997 - on ly 1 patch) Disphyma australe 0 (1987-90) , c ( 1997) Dysoxylum spectabile s ( N end, tallest 2.5 m in 1997) Entelea arborescens s Eriobotrya japonica* s (1 plant A u g 87 & June 88) Euphorbia peplus* 0 Fumaria muralis* s A K 233751 Galium aparine* o (above western beach) Geniostoma ruprestre 0 Geranium solanderi 0 Haloragis erecta 0 Hebe stricta var. stricta o (N end only) A K 233749 Helminthotheca echinoides* 0 Hypochoeris radicata* s Kalanchoe (cult ivar)* P (2 plants 1997, removed) Leontodon taraxacoides* c Leucopogon fasciculatus c Ligustrum sinense* s (only seen 23/8/87) Linum bienne* o (seasonal) Litsea calicaris s (one 3 m tall at N end 1997) Lobelia anceps s Lotus suaveolens* a (seasonal) Medicago polymorpha * c Melicytus rami floras 0 Melilotus indicus* lc Metrosideros excelsa a Muehlenbeckia complexa la Myrsine australis s (3 plants 19/8/87) Orobanche minor* 0 Oxalis rubens s Parsonsia heterophylla s Passiflora sp.* s Phytolacca octandra* o (seasonal) Pimelea cf. urvilleana lc Pittosporum crassifolium a P. tenuifolium s Plantago lanceolata* c Polycarpon tetraphyllum * o (seasonal)

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Pseudopanax arboreus s ( l tree 19/8/87)

P. crassifolius s

P. 1 ess on ii s Ranunculus reflexus s Raphanus raphanistrum* s Rumex sp. * s Senecio bipinnatisectus * o (seasonal) S. glomerulus s (seasonal) S. hispidulus s ( l plant 1997) A K 233752 S. lautus var. lautus o (seasonal) Solarium americanum s (seasonal)

S. nigrum* o (seasonal) Sonchus oleraceus* o (seasonal) Trifolium dubium* 0

Ulex europaeus* c (but less in 1997) Vicia saliva* c (seasonal) V. sp.* (small-leafed sp.) c (seasonal)

Monocotyledons (18 + 14) Agave americana* s

Anthoxanthum odoratum* c (seasonal) Air a praecox* 1 A K U 22502 Bromus arenarius* s A K U 21358 B. diandrus* c (seasonal) B. hordeaceus* o B. willdenowii* 0

Car ex breviculmis 0

C. flagellifera () Cordyline australis 0 (1987-90) , s ( l dead tree in C. Pumilio (possibly hybrid o (all < 2 m)

C. pumilio x C. australis) Cortaderia selloana* s ( l plant 19/8/87 & 1997) Cyperus ustulatus s Dactylis glomerata* a Dianella nigra s Festuca arundinacea* o

Gahnia lacera 0

Gladiolus undulatus* lc (above western beach) Isolepis nodosa a

Lachnagrostis billarderei s L. filiformis c Lagurus ovata* lc (seasonal)

Microlaena stipoides c Oplismenus imbecillis la Phormium tenax a (1987-90), c ( 1 9 9 7 )

Poa anceps o P. pus ilia o A K U 21020 Rytidosperma sp. c Rhopalostylis sapida s ( a t N e n d in 1997, a l l < 1.5 Sporobolus africanus* c Stipa stipoides s Vulpia bromoides* o (seasonal)

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Table 2. Provisional Non-vascular Plant List for Te Haupa Island

Lichens Parmotrema robustum Rimelia austrocetrata R. reticulata Usnea angulata U. rubicunda

W E L T 5551 W E L T 5552 W E L T 5553 W E L T 5554 W E L T 5555

Bryophytes Bryum sp. Desmatodon lingulatus Didymodon torquatus Hypnum cupressiforme Lunularia cruciata Marchantia sp. Metzgeria furcata Ptychomnion aciculare Tortella rubripes Tortula princeps Brachytheciaceae (Fami ly ) sp.

A K 234795 A K 234796 A K 234790 A K 233757

A K 233758 A K 233756 & 234792 A K 234793 A K 234794 A K 234791

DISCUSSION

Fauna The small colony o f grey-faced petrels on Te Haupa is fortunate to have

survived in the presence o f Norway rats. Imber (1975, 1976) found that grey-faced petrels nesting in low density colonies suffered total breeding failure in the presence of Norway rats on Whale Island (Moutohora) in the Bay o f Plenty. Rat predation o f grey-faced petrels is confined to eggs and chicks (Imber 1975, 1976). Fortunately, without predation on adults, even a small grey-faced petrel colony can survive for decades in the presence of rats because adults are very long- l ived (e.g. Cossee 1998, G T & A T unpubl . data). F o l l o w i n g the eradication of rats in 1989, we would expect breeding success to improve and by now some recruitment o f chicks into the breeding population may have occurred.

The extensive intertidal reef provides good feeding habitat for threatened ( M o l l o y & Davis 1994) wading birds, such as reef herons, variable oystercatchers and New Zealand dotterels.

Sub-fossil bones (of Pycroft's petrel and kaka) could indicate that Te Haupa was a much richer site for birds in the past. Te Haupa is close to the current breeding range of both species (e.g. Heather & Robertson 1996), so both could

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have occurred here naturally in the past. Alternatively, these remains may have been transported to the islands as human food.

Undoubtedly rodents have had a severe impact on terrestrial invertebrates. Mice should be eradicated as soon as possible, especially as they may have only become established since 1989. Perhaps Te Haupa 's most important conservation feature is that it lies beyond the normal swimming range of rodents and is free o f large mammals. Once mice are eliminated, Te Haupa would be suitable as a site for transferring rare species. For example, Taylor (1989) noted that "The island may be suitable for transfers of endangered snails, lizards and giant wetas".

Flora Some succulent species o f plants seemed to have increased in abundance

between 1987-90 and 1997, e.g. New Zealand ice plant (Disphyma australe). D i d Norway rats chew such plants for moisture? Taupata (Coprosma repens) was largely confined to coastal cliffs on Te Haupa. Cameron & Taylor (1997) thought that taupata may be affected by rat browsing on islands with a water shortage. This may explain its rarity on a coastal island with seemingly ideal habitat. The absence o f other succulent species normally common on relatively undisturbed northern islands, especially glasswort (Sarcocornia quinqueflora) and Einadia spp. (de Lange et al. 1995), may well be due to rat browsing.

Interestingly, karo was extremely abundant on Te Haupa and seedlings, saplings and old trees were present. Norway rats clearly have little impact on the regeneration o f this species. B y contrast, Pacific rats (kiore) (Rattus exulans) and ship rats (R. rattus) eat the fruit and chew the bark on trees and can virtually eliminate karo from an island (Atkinson 1986, Tennyson et al . 1997). The scarcity of houpara (Pseudopanax lessonii) and mapou (Myrsine australis) on Te Haupa was surprising. Are these species more susceptible than karo to Norway rat impacts?

Other plant species have clearly decreased since 1987-90 because of growth of existing vegetation which has over-topped shade-intolerant species, e.g. flax and gorse. Other plants have arrived recently, presumably as a result o f bird dispersal, as only seedlings or saplings were found, e.g. totara, kohekohe (Dysoxylum spectabile) and mangeao (Litsea calicaris).

The lack of permanent freshwater on Te Haupa could explain the decrease of the tree ferns Cyathea dealbata and C medullaris between visits. These species may be unable to properly establish in the dry sandy soils and may be kil led off during droughts. Tree ferns were certainly not a "predominant" plant species on the island, as stated in the Conservation Management Plan (DoC 1995).

Tennyson et a l . (1997) recorded 187 vascular plant species on the Moturekareka Island group of three islands (the largest o f which is 19 ha). Although this group lies only 5 k m north-east o f Te Haupa, 30 plant species

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found by us on Te Haupa were not recorded there. These include 1 fern (Pellaea), totara, 21 dicots and seven monocots. Interesting species omissions from the Moturekareka group list, which we found on Te Haupa, were native broom (Carmichaelia), Coprosma areolata, karamu (Coprosma robusta), kohekohe, mangeao, Pittosporum tenuifolium, five-finger (Pseudopanax arboreus), lancewood (Pseudopanax crassifolius) and nikau (Rhopalostylis sapida). A l l these forest plants have presumably been carried as seeds to Te Haupa by birds from nearby mainland forests. Other species on Te Haupa, such as Cakile, Aira praecox and Lagurus ovata, prefer sandy soils - a habitat which is scarce on the Moturekareka group.

Most o f the plants on Te Haupa were native species (58 %), but no nationally threatened plant species occurred (see Cameron et al . 1995). N o introduced plants have established from plantings on Te Haupa and there were remarkably few invasive naturalised species present. This contrasts with neighbouring islands, such as the Moturekareka group which has a pine plantation, many escaped orchard/garden plants and major infestations o f other weeds, such as bone-seed (Chrysanthemoides monilifera) (Tennyson et al. 1997). Potentially invasive species on Te Haupa include pampas grass (Cortaderia selloana), loquat (Eriobotrya japonica), privet (Ligustrum sinense), Passiflora and bone-seed. These species are currently scarce and should be controlled before they spread. Fortunately, the later three species were not even seen in 1997, so clearly have not spread much, i f at a l l , since 1987-90. Gorse was the most widespread invasive weed. It w i l l continue to be shaded out as the native bush regenerates, but may persist on some cliffs.

Future management It would be useful to carry out regular monitoring o f significant native

species such as grey-faced petrels and the native snail Succinea archeyi and to ensure that rodents don' t reinvade (once eradicated) and new invasive naturalised species don't establish. In the long term, fire is perhaps the most serious threat to the conservation values of Te Haupa. Signs could be erected to make campers aware of the island's values and the fire risk.

A C K N O W L E D G E M E N T S

This work was main ly carried out in our own time but w o u l d not have been possible without the transport provided by: D o C ' s A u c k l a n d Conservancy in June 1988, the A u c k l a n d Univers i ty Z o o l o g y Department in A u g u s t 1987 - June 89, the A u c k l a n d Reg iona l C o u n c i l in M a y 1990, Graeme A n d e r s o n (boat - Lady May) in A u g u s t 1990, and S y l v i a Watson and R o b i n B e r h o e f i n 1997. Thanks to a l l those mentioned in the text w h o helped us in the field, G w e n d a Pulham for arranging transport for the last two trips, Barbara P o l l y and Jessica Beever for identifying l ichens and mosses, K a r e n M a h l f e l d for ident i fying snails and p rov id ing the snail reference, P h i l S i r v i d for ident i fying spiders, E w e n C a m e r o n for assistance w i t h plant iden t i f i ca t ion and for pass ing on h i s to r ica l information supplied by Robert Brassey and M a r i e A l p e ( D o C A u c k l a n d staff), Bruce H a y w a r d for

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geological advice, the late Graeme Anderson for p rov id ing information about Te Haupa , D i c k V e i t c h ( D o C A u c k l a n d ) for p r o v i d i n g access to D o C ' s T e Haupa file and informat ion on recent rodent poisoning operations. E w e n Cameron provided helpful comments on the text.

R E F E R E N C E S

A t k i n s o n , I . A . E . 1986: Rodents on N e w Zealand 's northern offshore islands: distribution, effects and precautions against further spread. Pp. 13-40 in: Wr igh t , A . E . & Beever, R . E . (eds). The offshore islands o f northern N e w Zealand. New Zealand Department of Lands and Survey Information Series 16.

B e l l , B . D . ; Brathwaite, D . H . 1964: The birds o f Great Barr ier and A r i d Islands. Notornis 10:363-383.

Cameron , E . K . ; de Lange, P.J . ; G i v e n , D . R . ; Johnson, P . N . & Ogle , C . C . 1995: N . Z . Botan ica l Society Threatened and Loca l plant lists (1995 revision). New Zealand Botanical Society Newsletter 39: 15-28.

Cameron, E . K . & Taylor , G . A . 1997: F lora and fauna o f Sentinel R o c k , Mangawha i Heads, Northern N e w Zealand. Tane 36: 15-25.

C l i m o , F . M . 1980: Add i t iona l fossil records o f Succinea (Austrosuccinea archeyi) (Powel l ) ( M o l l u s c a : Succineidae) in N e w Zealand. Journal of the Royal Society of New Zealand 10:21-30.

Cossee, R . O . 1998: Report on b i rd banding in N e w Zealand 1994/1995. Department o f Conservat ion, Wel l ing ton . Science for Conservation: 72.

de Lange, P.J . ; Cameron , E . K . & Taylor , G . A . 1995: F lora and fauna o f Tatapihi (Groper) Island, M o k o h i n a u Islands. Tane 35: 69-94.

de Lange, P .J . & Crowcrof t , G . M . 1996: The vascular flora o f Maunganui (Casnell) Island, Scott 's Landing , Mahurangi Harbour. Auckland Botanical Society Journal 51(2): 38-49.

D o C 1995: Conservat ion Management Strategy. Department o f Conservat ion. A u c k l a n d . G i b b , J . A . & W i l l i a m s , J . M . 1990: European rabbit. Pp. 138-160 in: K i n g , C M . (ed). The

Handbook o f N e w Zealand M a m m a l s . Oxfo rd Univers i ty Press, A u c k l a n d . Heather, B . D . & Robertson, H . A . 1996: The F ie ld Gu ide to the Bi rds o f N e w Zealand. V i k i n g ,

A u c k l a n d . Imber, M . J . 1975: Petrels and predators. XII Bulletin of the International Council for Bird

Preservation: 260-263. Imber, M . J . 1976: Breeding b io logy o f the grey-faced petrel Pterodroma macroptera gouldi. Ibis

775:51-64. M o l l o y , J . & Davis , A . 1994 (2nd edition compi led by C . Tisda l l ) : Setting priorities for the

conservation o f N e w Zealand 's threatened plants and animals. Department o f Conservat ion, Wel l ing ton .

M o o r s , P .J . 1990: N o r w a y rat. Pp. 192-206 in: K i n g , C M . (ed). The Handbook o f N e w Zealand M a m m a l s . Oxfo rd Univers i ty Press, A u c k l a n d .

Taylor , R . H . 1984: Distr ibut ion and interactions o f introduced rodents and carnivores in N e w Zealand. Acta Zoologica Fennica 172: 103-105.

Taylor , G . A . S . 1989: A register o f northern offshore islands and a management strategy for island resources. Department o f Conservat ion, A u c k l a n d . Northern Regional Technical Report Series No. 13.

Tennyson, A . J . D . & Taylor , G . A . 1990: Behaviour o f Pterodroma petrels in response to "war whoops". Notornis 37: 121-128.

Tennyson, A . J . D . ; Cameron , E . K . & Taylor , G . A . 1997: Fauna, flora and history o f Moturekareka, Motutara and Kohatutara Islands, Hauraki Gu l f . Tane 36: 27-56.

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