For the love of seabirds

Many of northern New Zealand’s seabirds are out of sight and out of mind for most of us.  

They live on the wing, migrating and foraging long distances across the open ocean. When they come to land to breed and rear chicks, they do so in remote coastal areas, or on small, uninhabited islands in Tīkapa Moana, the Hauraki Gulf. But these seabirds are under pressure. 

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“They’re the most threatened group of birds in the world,” says Edin Whitehead, PhD student at Waipapa Taumata Rau University of Auckland. “They face threats at sea and on land, it’s a double whammy.” 

Climate change, mammalian predators, plastic pollution, oil spills, fisheries bycatch, diseases, light pollution – the list goes on. Whitehead investigated them all for a 2019 report titled Threats to Seabirds of Northern Aotearoa New Zealand.   

Putting together this report helped her identify some knowledge gaps which then guided the focus for her research.  

Whitehead is studying four species of seabirds that breed in the Hauraki Gulf but travel different distances for migration – from long distance (rako, Buller’s shearwater), to shorter (totorore, little shearwater, and tītī wainui, fairy prion) to the homebirds that don’t tend to migrate (pakahā, fluttering shearwater). 

Over the last three years she has visited islands in Tīkapa Moana where these birds breed. There, she assessed their health and foraging movements to see how both adults and chicks are doing during the intense period of chick rearing.  

GPS tagging a subset of the birds has allowed Whitehead to get a glimpse into what areas of the ocean are important to them for finding food. On land, weighing the chicks, analysing their regurgitations or faeces, and sampling feathers to analyse for stress hormones, will give her an idea of how the feeding is going, and what the health of the colony is.   

Now she is moving on to the analysis phase of her PhD – in the next few months she will line up the GPS tracking data with sea surface temperatures and extract the corticosterone stress hormone from the adult and chick feathers.   

But even before getting into this analysis there are clear signs that things are not good. Witnessing the last breeding season was particularly hard, Whitehead says. On the largest of the Poor Knights Islands, Tawhiti Rahi, in their study plot, she came across rako chicks that were underweight, some starving to death.  

Whitehead, and colleagues in the seabird research world, believe that this particularly dire breeding season for some seabird species is linked to the La Niña effect and compounded by climate change. This resulted in an extended period of warmer-than-normal ocean temperatures in Tīkapa Moana last year.  

“Seabirds get called indicators of ocean ecosystems a lot, and there’s a lot of caveats with what they’re actually telling you, but if a lot of them are showing up dead, there’s nothing good that’s coming of that,” she says, referring to the reports of hundreds of kororā washing up on Far North beaches.   

But Whitehead says we do have tools to help, and while we might not be able to instantly solve climate change, we can urgently address some of the other threats seabirds face to give these resilient birds some room to adapt.  

Edin would like to acknowledge mana whenua of Tawhiti Rahi, Mauimua, and Pokohinu, Ngātiwai, Ngāti Manuhiri and Ngāti Rehua for the privilege of working in their rohe. Funding support for this research was from the Birds New Zealand Research Fund (2019, 2020, 2021) and the Newmarket Rotary Club Environmental Award 2022. This research is done in collaboration with the Northern New Zealand Seabird Trust.   

To learn more:  

• Listen to Seabird hotspot - the Poor Knights Islands episode from 2018

• The State of our Seabirds 2021 is a comprehensive publication edited by Chris Gaskin looking at seabird ecology, research and conservation for the wider Tīkapa Moana Hauraki Gulf region. 

• You can read the Threats to Seabirds of Northern Aotearoa New Zealand 2019 report here. 

• In good news, with extensive conservation efforts backing it, the tara iti fairy tern has just had its best breeding season in ten years.  

• Find more about the reports of dead kororā washing up on beaches here.