BIRDS O F M O T U H O R A ( W H A L E ISLAND) , B A Y O F P L E N T Y , N E W Z E A L A N D

by C . A . Butts 1 and M . A . Potter2

Department of Animal Science, Massey University, Palmerston North 'Department of Ecology, Massey University, Palmerston North

S U M M A R Y

The birds of Motuhora (Whale Island) were surveyed over a 9 day period during the summer of 1985/1986. Observations of bird species and habitat were recorded. Sightings of recently used nests, eggs, chicks or fledglings were regarded as evidence for breeding. Overall, 40 species of bird were observed alive, 25 of these species were recorded breeding, and 12 species of bird were found beach wrecked.

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

Motuhora (Whale Island) is a small island lying approximately 8 km off shore in the Bay of Plenty, New Zealand (latitude 37°51' S; longitude 176°59' E). The geology of Motuhora has been described by Ramsay and Hayward (1951). The island has an area of approximately 162 ha and rises steeply to a height of 353 m. It is 2.4 km long from east to west and nearly 1 km wide. The vegetation of Motuhora, comprising pohutakawa forest, kanuka scrub, grassland, swamp, and strand, has been described in detail by Parris (1971), Parris et at (1971), Beever and Brownsey (1990), Hayward and Hayward (1990) and Ogle (1990).

The birds of Motuhora were surveyed during an Offshore Islands Research Group Expedition from 28 December 1985 to 5 January 1986 (Wright 1990). The species recorded are grouped according to the habitat in which they occurred. We regarded sightings of eggs, chicks, fledglings or recently used nests as evidence for breeding. Common and scientific names used here follow Robertson (1985).

BIRDS

Birds observed in the predominantly pohutakawa forest were rock pigeon (Columba livid), shining cuckoo (Chrysococcyx lucidus lucidus), hedge sparrow (Prunella nodularis occidentalism grey warbler (Gerygone igata), pied fantail (Rhipidura fuliginosa placabilis), song thrush (Turdus philomelos clarkei), blackbird (Turdus merula merula), silvereye (Zosterops lateralis lateralis), tui

141 Tane, Vol 34, 1993

(Prosthemadera novaeseelandiae novaeseelandiae), chaffinch (Fringilla coelebs gengleri), greenfinch (Carduelis chloris chloris), goldfinch (Carduelis carduelis britannica), redpoll (Carduelis flammea cabaret), yellowhammer (Emberiza citrinella caliginosa), house sparrow (Passer domesticus domesticus), starling (Sturnus vulgaris vulgaris) and myna (Acridotheres tristis).

The birds observed in or above the predominantly kanuka scrub were skylark (Alauda arvensis arvensis), welcome swallow (Hirundo tahitica neoxena), hedge sparrow, grey warbler, pied fantail, song thrush, blackbird, silvereye, tui, chaffinch, greenfinch, goldfinch, redpoll, house sparrow, starling, and myna.

Birds observed in or above grass, swamp and bracken were Australasian harrier (Circus approximans), rock pigeon, song thrush, blackbird, redpoll, yellowhammer, starling and myna.

Species of bird observed on the coast and beaches included little blue penguin (Eudyptula minor iredalei), black shag (Phalacrocorax carbo steadi), pied shag (Phalacrocorax varius varius), little shag (Phalacrocorax melanoleucos brevirostris), variable oystercatcher (Haematopus unicolor), New Zealand dotterel (Charadrius obscurus), Dominican gull (Larus dominicanus), red-billed gull (Larus novaehollandiae scopulinus), Caspian tern (Hydroprogne caspia), white-fronted tern (Sterna striata) and welcome swallow.

Observations of birds at sea taken from either the island or the launch while travelling between Motuhora and Whakatane gave the following list of species: little blue penguin; northern giant petrel (Macronectes halli); grey-faced petrel (Pterodroma macroptera gouldi); flesh-footed shearwater (Puffinus carneipes); Buller's shearwater (Puffinus bulleri); sooty shearwater (Puffinus griseus); short-tailed shearwater (Puffinus tenuirostris); fluttering shearwater (Puffinus gavia); Australasian gannet (Sula bassana senator); pied shag; Arctic skua (Stercorarius parasiticus); Dominican gull; red-billed gull; Caspian tern; and white-fronted tern.

The species of bird found beach wrecked around the coast of the island were little blue penguin, flesh-footed shearwater, Buller's shearwater, sooty shearwater, short-tailed shearwater, fluttering shearwater, northern diving petrel (Pelecanoides urinatrix urinatrix), Australasian gannet, pied shag, Dominican gull, red-billed gull and white-fronted tern.

The species of bird observed breeding on the island were little blue penguin, grey-faced petrel, sooty shearwater, variable oystercatcher, New Zealand dotterel, Dominican gull, red-billed gull, white-fronted tern, rock pigeon, skylark, welcome swallow, hedge sparrow, grey warbler, pied fantail, song thrush, blackbird, silvereye, tui, chaffinch, greenfinch, goldfinch, redpoll, yellowhammer, house sparrow, and starling.

142 Tane, VoL 34, 1993

DISCUSSION

Thirty-five of the bird species we found had been noted by Croxall and Millener (1971) during their two visits in July and August 1970, but we recorded a further five species previously unreported from the island. These were sooty shearwater (breeding), welcome swallow (breeding), short-tailed shearwater, arctic skua and shining cuckoo. We also note the first published breeding records on Motuhora of red-billed gull, white-fronted tern, rock pigeon, grey warbler, song thrush, hedge sparrow, tui, silvereye, greenfinch, goldfinch, redpoll, chaffinch, house sparrow and starling. Of particular interest were the three pairs of the rare New Zealand dotterel found breeding amongst the sand dunes of Camp Bay. Three dotterel chicks were observed during our short stay on Motuhora.

Nine species of bird previously recorded from Motuhora (Croxall and Millener 1971) were not sighted during this expedition. These were black-browed mollymawk (Diomedea melanophrys), Salvin's mollymawk (Diomedea cauta salvini), Cape pigeon (Daption capense), prion sp. (Pachyptila sp.), Australian brown quail (Synoicus ypsilophorus), morepork (Ninox novaeseelandiae), kingfisher (Halcyon sancta vagans), tomtit (Petroica macrocephala), and kaka (Nestor meridionalis).

The species list for Motuhora and its surrounding waters now stands at 49. Twenty-five of these species have been observed breeding on the island. The large number of species (35) recorded both here and by Croxall and Millener (1971) implies that the avifauna of Motuhora is fairly stable. Four of the nine species recorded by Croxall and Millener (1971), but not here, were seabirds. The observation of seabirds is greatly affected by season and prevailing wind conditions. During our stay the weather was calm on the island but a strong westerly front passed over the North Island. Croxall & Millener (1971) gave no details of weather or prevailing wind conditions.

We observed no goats, rabbits or rats on the island, although all three mammals were present during the 1960's and 1970's (Anderson 1971; Bettesworth and Anderson 1972; Ogle 1990). The goats were reduced in number during 1964 (Anderson 1971) and were eradicated between 1970 and 1977 (Ogle 1990). Intensive poisoning operations, aimed at the rat and rabbit populations, were undertaken during the 1970's and 1980's with the last occurring in August 1985 by Wildlife Service (now Department of Conservation) staff (Ogle 1990). These operations were apparently successful at eradicating both species from Motuhora. At present the avifauna of Motuhora appears to be safe from introduced mammalian predators. Every care needs to be taken by all visitors to the island to prevent any future introductions.

143

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

We thank Dr Robin Fordham for his valuable comments on this manuscript, and Dr Colin Ogle, Ian Southey and the other members of the 1985 Offshore Island Research Group Expedition for their assistance with bird sightings.

R E F E R E N C E S

Anderson, G .R .V . 1971: Auckland University Field Club Scientific Camp Whale Island, August 1970. Tane 17: 5-8.

Beever, J.E. & Brownsey, P.J. 1990: Mosses of Whale Island (Motuhora), Bay of Plenty, New Zealand. Tone 32: 49-60.

Bettesworth, D.J. & Anderson, G .R .V. 1972: Diet of Rattus norvegicus on Whale Island, Bay of Plenty, New Zealand. Tane 18: 189-195.

Croxall, J. P. & Millener, P.R. 1971: The birds of Whale Island. Their status and distribution. Tane 17: 53-60.

Hayward, B .W. & Hayward, G.C. 1990: Lichens of Whale (Motuhora) and Rurima Islands, Bay of Plenty, New Zealand. Tane 32: 61-71.

Ogle, C .C . 1990: Changes in the vegetation and vascular flora of Motuhora (Whale Island) 1970-1986. Tane 32: 19-48.

Parris, B.S. 1971: The vegetation of Whale Island. Part II. Species list of vascular plants. Tane 17: 39-46.

Parris, B.S., Lynch, P .A. & Ferguson, J.E. 1971: The vegetation of Whale Island. Part I. The plant communities. Tane 17: 33-38.

Ramsay, W . R . H . & Hayward, B .W. 1971: Geology of Whale Island (Motuhora). Tane 17: 9-32. Robertson, C.J.R. (ed.) 1985: Readers' Digest Complete Book of New Zealand Birds. Readers Digest

Service Ltd, Sydney. Wright, A . E . 1990: Offshore Islands Research Group Scientific trip to Motuhora (Whale Island) New

Year 1985-1986. Tane 32: 17.

144