Guest post by Paul Cuming. Ōi, our burrowing seabird neighbours, the northern muttonbird.

Paul Cuming is a mild-mannered librarian by day, and a seabird defender by night. Based in Tauranga, he divides his spare time between running the local branch of BirdsNZ, occasionally training teens in the art of bird banding and mistnetting, and coaching visiting backpackers in the fine art of falling off a surfboard. He is also a founding member of the Western Bay Wildlife Trust, lectures on native bird calls and kills the odd varmint in the local park.

Paul Cuming and friend, grey faced petrel,
ōi, or kuia. Checking identification bands,
growth and weight during a night survey in
the Western Bay of Plenty. Source:
Paul Cuming (2018).

One of the most exciting projects Paul has been involved with is the groundbreaking successful transfer of seabird chicks from an offshore island to a mainland colony. Here in the Bay of Plenty  colonies of Pterodroma macroptera gouldi (ōi, kuia, or grey faced petrel) can be found on the Ruamaahua (Aldermen Islands) off the coast of east Coromandel, and on the Ōhiwa Headlands in our very own backyard. To find out more about this fascinating bird and the successful transfer project read on.......

There are several significant colonies of petrel on our mainland and offshore islands in Aotearoa. Most well known is the cousin to the petrel, Puffinus griseus (titī or sooty shearwater) found on the Rakiura Titī Islands (near Stewart Island), where the colony is managed and sustainably harvested for the birds most of us will be more familiar with as “muttonbird”. However, less well known is the ground-burrowing seabird called grey faced petrel, ōi or kuia,  Pterodroma macroptera gouldi. 

Here in the Bay of Plenty ōi can be found on the Ruamaahua (Aldermen Islands) off the coast of east Coromandel, and on the Ōhiwa Headlands in our very own backyard. Moutohorā (Whale Island) is home to one of the largest ōi populations, comprising approximately 50,000 breeding pairs. Historically this species has been harvested by tangata whenua, giving rise to it’s unofficial name the “North Island muttonbird”. In pre-European times the harvested birds were preserved in their own fat, and stored in kelp buckets. Ngati Awa, tangata whenua of Moutohorā (Whale Island) refer to this species as kuia, while more widely through the North Island it is known as ōi.

Harvesting of mainland ōi was prohibited by the Department of  Internal Affairs under the Grey Faced Petrel (Northern Muttonbird Notice (1958)) and the 1953 Wildlife Act. Mainland Harvesting is still prohibited, but the Petrel Project on Ruamaahu (Alderman) Islands includes monitoring and management of a sustainable harvest by local tangata whenua. 

The ōi is the most common species of petrel in the North Island, breeding on headlands and islands. The birds feed at sea during the day, and at sunset the birds return to their burrows, where they are nocturnally active. You are most likely to see these birds at sea in the air, or resting on the water. Feeding takes place in the open at distances over 100 kilometres from land where the continental shelf ends. Distance is no limit in the search for food, with some birds recorded flying almost as far as the east coast of Australia while the partner remains on the egg.

Ōi, or grey faced petrel as it flies above the ocean surface
seeking food off the coast of Victoria in Australia.
Source: Ed Dunens.

Satellite tagging from the Ruamaahua project shows birds frequently fly to Australia's East Coast, up past Norfolk Island to New Caledonian waters in the North, and over to the Southern Pacific Ocean around 800km South of Pitcairn Island, about 2500km East of New Zealand. Our studies have shown on Mauao (Mount Maunganui) that the same birds use the same burrows each year and 'extend' their burrows. The same groups of birds associate with one another from year to year as the metal band numbers from recaptures in the same areas each year often are only one or two digits different [banded at the same time, recaptured together]

Like all mainland nesting seabird sites, including Onekawa Te Mawhai Regional Park near Ōhiwa, ōi have had to put up with a lot of challenges to the very existence of the species. The current problem is well-established – pests introduced by humans. An additional challenge to the species, especially in the wider Bay of Plenty, is coastal erosion caused by large-scale events such as tropical cyclones. Between them, for example, Tropical Cyclones Cook and Debbie, only a month apart in 2017, carved off significant amounts of soil from our mainland study site Mauao (Mount Maunganui) which included dozens of ōi burrows. The same systems significantly damaged the canopy of the pest-free offshore island Motuotau (Rabbit Island), also home to the small cousin of the ōi, the Kuaka (Common Diving Petrel).

So, how do we know all this about ōi? In 1989, we were given the privilege of establishing the population dynamics of the ōi colony on Mauao in partnership with the Department of Conservation (DoC). Who were we? We were members of the Ornithological Society of New Zealand, an organisation which has specialised in the study of wild birds since 1939. Our control site, the pest free Motuotau, was used to compare the effects of pest control on the numbers of birds using the mainland Mauao site. Eleven years later, after the Mauao colony was shown to be viable - but with a proviso of continued pest control - Mauao was then selected by DoC to become the pioneering site for a landmark project – the successful transfer of seabirds from an existing colony to a new site. 

Marcus Richards returns a successfully fledged ōi to it's burrow 
after monitoring for growth, weight and condition. 
Source: Paul Cuming (2018).

Ōi chick nesting in an artificial burrow on Mount Maunganui. Artificial
burrows can provide a more stable habitat and
 also reduce competition for habitat. Source: Paul Cuming (2018).

Healthy ōi chick being returned to it's burrow after monitoring for
growth, weight and condition. Source: Paul Cuming (2018)

Thirty ōi chicks from Motuotau were moved to Mauao in the spring of 2000. Many ‘golden rules’ were learned, but the two I will explain are fascinating. Firstly, you must transfer chicks BEFORE they waddle out of the burrow and look at the sky. This allows a bird to return to the place they were born, in effect fixing their onboard GPS-style navigation from that point. So it is no use transferring any chicks which are older. The other is diet, what to feed the chicks after the transfer. Because you become their parents. Various tricks have been learnt since, and diet varies between types of seabirds (shearwaters and prions have subsequently been successfully transferred at other locations in the country)..  

The extra effort involved with transferring chicks to areas absent of acoustic noises of petrels was avoided by transferring chicks directly into an existing colony of adult birds making all sorts of colonial noises! So this resolved the issue of setting up acoustic anchoring sound systems, which are compulsory if transferring to starter colonies. Our project team spent time away from the site studying and helping with other species’ projects and gaining transfer knowledge; mainly on Red Mercury, Maud, Matiu, Mana and Cabbage Tree Island in New South Wales. Our project was successful and we still see some of those chicks today with bright red colour bands in addition to their metal bands. These techniques were initially developed in New Zealand for land bird species such as the Chatham Island Black Robin. So why transfer a relatively common species of bird?  

We need to go back to the Chatham Islands to find our answer - the closest species of birds to the ōi, the tāiko, or Magenta Petrel. The tāiko numbers less than 200 and the population is described as nationally critical. The tāiko needed to be transferred to a pest free area being established in the Chatham Islands, offshore of the main island where they were just hanging on. The tāiko were too precious to be experimented with, as any losses of the birds would be unacceptable on all levels, especially on a genetic level. So, in effect, we were using one species of bird to save another, by studying and learning through our mistakes - and what not to do - on a more common species.

It is important to note that this knowledge was gained  while operating in partnership with DoC, and we would not have been able to do this without their express permits or permissions. It is also of note to mention we were really only helping them carry out this pioneering work under their auspices. We were willing passengers on this journey and are still thankful this knowledge still exists under the umbrella of the Department of Conservation today - and within the leader of the transfer project, Graeme Taylor, current DoC Principal Science Advisor.

We would also like to acknowledge the work of the Ōhiwa Headlands Sanctuary Trust and the Department of Conservation in actively managing and monitoring the grey-faced petrel colony at Ōhiwa Headlands, and significant pest-control activities in the area.

Neo the Conservation Dog sniffing out a burrow during a 2014 survey
of grey-faced petrel at Ōhiwa Headlands. 
Source: Mithuna Sothieson/OHST.

If you would like to explore these fascinating birds and this project further, several articles have been published in Notornis, the magazine of the New Zealand Ornithilogical Society.


Clifford, H. J. (2001). Ten years studying grey-faced petrel  (Pterodroma macroptera gouldi) at Mauao/Motuotau. Notornis, 48(3), 183-183.

Greene, B. S., Taylor, G. A., & Earl, R.. (2015). Distribution, population status and trends of grey-faced petrel (Pterodroma macroptera gouldi) in the northern North Island, New Zealand. Notornis, 62(3), 143-161.

Jones, C. J., H.Clifford,, Fletcher, D., Cuming, P., & Lyver, P. O. 'B.. (2011). Survival and age-at-first-return estimates for grey-faced petrels (Pterodroma macroptera gouldi) breeding on Mauao and Motuotau Island in the Bay of Plenty, New Zealand. Notornis, 58(2), 71-80.

Taylor, G.A. 2013. Grey-faced petrel. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz