Manu Moana: a bird’s eye view

Once a global seabird stronghold, Tīkapa Moana – the Hauraki Gulf – is now sounding the alarm. In this episode, we explore how seabirds, the storytellers of the sea, reveal the growing pressures on our ocean and what their decline means for the future of Aotearoa’s marine life.

Episode Transcript

Manu Moana (00:00):
‘A Bird’s Eye View’ Transcript

(00:01):
Gabriel TongaawhikauThis podcast is brought to you by Tamaki Paenga Hira Auckland War Memorial Museum.
Laura SkerrittThe ocean has always been a place of wonder — vast, full of life, and essential to our survival. But pressures from human activity, pollution, and industrial fishing are unravelling its delicate food webs. At the top are seabirds — the storytellers of the sea — and they’re sounding the alarm. Here in Tīkapa Moana, the Hauraki Gulf, lies one of the world’s great seabird strongholds. Twenty-seven species breed here, nearly a third of all those in Aotearoa. Yet their numbers have fallen by almost 70 percent since the first humans arrived here.
Offshore wanderers have endured, but the birds we share our coastlines with — penguins, terns, gulls, shags — continue to decline. And it matters.
Aotearoa holds the highest number of threatened seabird species in the world. Their fate is tied to ours, and the choices we make today will decide whether their voices still echo across the Gulf — or fall silent.
Kia ora, I’m Laura Skerritt, your host for this episode of The Amp, the podcast from Auckland Museum that amplifies the incredible stories from our collections, our mahi, and our place in the Pacific.In this episode, we explore the world of seabirds in the Hauraki Gulf — one of the planet’s most important seabird habitats. With insights from Doctor Matt Rayner, we uncover stories of species in decline, like the Kawau Tikitiki (spotted shag), and others adapting to human influence, like the Karoro (southern black-backed gull). Drawing on the Museum’s collections and new research, we’ll learn how seabirds reveal the changing health of our marine ecosystems and why protecting the Gulf is vital for their survival — and ours.
New Zealand has long been a paradise for seabirds. Surrounded by rich, productive oceans and dotted with countless islands and coastal habitats, it’s offered safe breeding grounds for millions of years. With no land mammals to threaten them before people arrived, seabirds flourished here in extraordinary numbers and diversity. The Hauraki Gulf - Te Moananui a toi, Tīkapa Moana in particular is a globally significant seabird hotspot, with many endemic species relying on the area.
Matt RaynerOne of the most significant areas in all of New Zealand. It's incredibly culturally significant to Aucklanders, but also to mana whenua. It's of high economic importance. It's been valued at around $100 billion by a study conducted in 2017 and it's of really incredible biological importance as an area of high biodiversity.
Laura SkerrittThat’s Dr Matt Rayner; he’s a Senior Researcher of Land Vertebrates here at the Museum.
The birds we tracked, they were traveling hundreds of kilometres a day within the Firth of Thames area. They were doing between 150 and 400 dives a day. Most of the dives were shallow to about four meters, but the birds were quite capable of diving to 20 meters. Just incredible birds. Like most shags, they need to come out and rest, because their feathers aren't completely waterproof, because what they do when they're foraging, they soak up a bit of water so they can dive more easily, but they then need to go somewhere to dry out. And listeners, if they have seen Kawau Tikitiki, they will most likely have seen them on the Thames coast, between Thames and Coromandel, where they sun themselves on the rocks, and that’s a really important area for them.
They love to forage on mussel farms, and there's probably a reason for that, and that we know from other research by researchers at the University of Auckland and others that there's lots of fish in mussel farms. There's lots of lines with mussels on them. We destroyed most of the mussels. The Firth of Thames used to be one giant mussel bed along the bottom. And in the 1950s and 60s, there was a huge mussel dredging industry in the inner Hauraki Gulf. Nearly the whole Gulf was mussel beds. We dredged that out, and mussels were pretty much exterminated by the mid-1960s, probably one of the reasons that Kawau Tikitiki kept declining. Anyhow, the birds love mussel farms, but they also love certain areas of their range down on the Thames coast, and we became concerned that this, these were also areas that had quite a high degree of fishing from recreational and commercial fishes. And two of the birds in our study were actually drowned in nets. So, since that time, we've been doing some work looking at the interaction of these birds with fisheries, which is a major area of concern, and we think that might be contributing to the decline of these birds.
Laura Skerritt So what’s next for the Kawau Tikitiki?Matt Rayner We now know that this little curious population in the Hauraki Gulf is genetically distinct from the rest of the country, which makes it even more worrying that it's endangered.
We need to get a handle on how many of these birds we’re killing in our nets. We think it's a really, a real problem. Both the birds are potentially drowning in commercial set nets in the southern Firth, but we also don't know. We know a lot of people are using recreational nets along that coast. So, we're going to be doing a citizen science project this spring, where we have volunteers are going to be doing surveys along the coast where the birds are roosting, and just counting, are there nets? Are people setting nets there? Near the birds. That could be threatening them. So that's, that's the real next focus of what's going on with our research.
Laura Skerritt Without the help of conservationists, Hauraki Gulf spotted shags could join the ranks of the approximately 55 other extinct birds that have been lost since humans arrived on our shores.
In contrast to the Kawau Tikitiki, the Southern Black-backed Gull, Karoro has thrived in human-dominated landscapes. A study by UNITEC and Auckland Museum revealed the bird’s adaptability and showed a dramatic shift in its diet over the past century, thanks to some fascinating scientific techniques and the Museum’s historical collections. Matt Rayner If the Kawau Tikitiki seems to be one of the losers in terms of what's going on of the Gulf, you could argue that the Karoro seems to be one of the winners, although I will show you how it's not. Karoro are super abundant, and they love feeding on our waste and our refuse. But it's not their historical role, and we wanted to, in this study, look at how the birds were using human food sources, and was there a difference between colony sites that were, say, closer to the city or further away.
Laura Skerritt When you think of gulls, you probably picture large, cawing scavengers, swooping down to snatch your hot chips at the beach, or tugging ferociously at bin bags. Opportunists these birds may be, but you’ve gotta hand it to them - they’re resilient survivors, uniquely able to adapt their behaviour and diet to a rapidly changing world. While often overlooked, new research is revealing just how remarkable these birds really are.  Their story is one of flexibility and urban success.  Matt Rayner So, for our study, we looked at three aspects of the Karoro biology. The first thing we used were what are called pellets. So basically, when seagulls eat stuff, the stuff they can't digest, they regurgitate up. So, if you go to where they congregate, or you go to their breeding colonies, you can find these pellets on the ground, and you can pull them apart and analyse what the birds have been eating. So, my collaborator at UNITEC used lots of volunteers to analyse many, many pellets from Karoro at three sites, one in Western Springs Park in Auckland City, a breeding the major breeding colony on Rangitoto Island, on the lava fields there, and a further site further away from the city, on Tiritiri Matangi island. So, we were able to look at the diet across that range.
Laura Skerritt Coastal seabirds are like messengers from the sea — they can reveal when human activity is starting to change the ocean environments close to shore. In the past, Karoro were coastal birds that hunted and scavenged in the ocean, eating fish, sea creatures like crabs and shellfish, and even the remains of mammals like sea lions. However, as Tāmaki Makaurau has grown into a sprawling city, the Karoro's diet has expanded too.Matt RaynerWe found, as we expected, that Karoro eat a lot of human based food. They eat a mixed diet marine invertebrates and fish invertebrates and refuse. But the amount of refuse that they eat increases with proximity to the city. So, the pellets from the birds at Western Springs Park and Rangitoto, just across the water from the city, were full of lamb bones, chicken bones, all sorts of stuff, whereas the pellets on Tiritiri Matangi had much more of a marine based component in their diet.
Laura Skerritt What they eat now tells a bigger story about what’s happening in the Hauraki Gulf. As marine ecosystems decline because of pollution, overfishing, and urban run-off, native seabirds like Karoro are forced to adapt, often in ways that lead to them living in our towns and cities among the hustle and bustle of daily human life. It’s both fascinating and a bit sad – how drastically our actions have reshaped these birds’ lives. Today, they’re just as likely to chow down on a discarded fried chicken drumstick or a roadkill mouse, as they are to hunt for fish.  Matt Rayner There was a second part to the study. So, we again, the isotopes came in here. So, we were interested in how the diet of Karoro has changed as Auckland City has developed over time, and obviously more and more of us are sticking out our wheelie bins and food trash bags. So again, we turned to isotopes, and again we turned to the collections which we had a good record of Karoro, specimens of Karoro collected from the late 1800s to today. And what this showed us, again through the isotopes, is that the diet of Karoro in the last century has swung hugely from a marine dominated diet to foods from a terrestrial based source, basically our rubbish.
Laura SkerrittSadly, the adaptability of Karoro is the exception, not the rule. Many other seabird species in the Hauraki Gulf are far more specialised, and they rely on healthy marine food webs to survive. As these ecosystems are degraded by pollution, overfishing, and climate change, these less flexible species are struggling – and in many cases, declining.So, while Karoro can make do with fries and chicken bones, others like terns, petrels, shearwaters, shags and penguins - can’t.  Their shrinking numbers are a warning sign that our actions are unravelling the natural balance of the Gulf. Matt RaynerWe certainly know that certain groups of species are adapting their diet. We know that particularly animals like the Karoro or seagulls around the world have been really good at adapting to human rubbish, that I think in their natural environment, they were quite adaptive. They fed on a broad variety of prey, from scavenging through to actively killing. There's been a recent paper studied, published from California that showed a seagull similar to the Karoro was tracked riding in a rubbish truck for about 80 kilometres in the truck while it was driving, feeding on the rubbish. So, this is how adaptable these birds are. The problem is that the Karoro gives a bit of a false signal. We look at these birds, we look at these birds picking at our fish and chips, and we think, oh, you know, things are alright. There's lots of Karoro around. But it's a false economy. A small number of species do well thanks to what we're putting out there, but unfortunately, other species, many other species, like the Kawau Tikitiki, are not doing well on there. They're declining towards extinction, and the general health of the Gulf is declining towards a much poorer state.
Laura Skerritt Next time you see a Karoro pecking at an overflowing bin, remember – it’s not just making do, it’s adapting to survive in a world we’ve changed– and not all seabirds are so fortunate. Protecting the Gulf means fighting for the future of all our native wildlife.Matt RaynerThe Karoro is really an indicator for us that the balance is out of whack, and the state of the environment is not good. So, what really is next is hopefully more marine protection for the bulk of biodiversity in the Gulf that's suffering.

Laura Skerritt The Hauraki Gulf / Tīkapa Moana Marine Protection Bill has just been passed into law, which is a huge step forward in terms of marine protection. The new legislation will be in place before the end of the year and create a network of protected areas across the Gulf — small sections of ocean set aside to regenerate, with the benefits flowing well beyond their boundaries. The goal is to make the Gulf more resilient to the pressures it faces every day (00:22):
things like sediment washing in from the land, pollution, and the growing impacts of climate change. Matt Rayner It's been the culmination of over 12 years, more like 15 years of work by a huge number of Aucklanders and people around the country. Auckland Museum has personally been involved in this through our work with the Neureuter trust at the noises, advocating for a marine protected area at the noises Islands, which are in the outer edge of the inner Hauraki Gulf, and that we've been quite successful. I say we, a broad coalition of a huge number of people, have been quite successful. It's going to bring in 19 new protected areas in total to the Gulf. It's going to result in two extensions to marine reserves at Hahei and at Goat Island. It's going to create 12 new high protection areas, marine protected areas, and also some sea floor protection zones.
Laura Skerritt We already know marine protection works. Places like Goat Island / Te Hāwere-a-Maki, Cathedral Cove / Whanganui-ā-Hei, and the Poor Knights / Tawhiti Rahi show us the difference it can make. But recovery doesn’t happen overnight. It takes time. Time, which sadly, a number of our seabird species just don’t have. And seabirds bring an extra challenge: they don’t stay in one spot. While reefs and seafloor habitats can bounce back when protected, seabirds range widely across the Gulf and far beyond. They need safe feeding grounds wherever they travel, not just around one reef or bay.  The new bill is an important step forward, but it still allows damaging fishing practices to continue across much of the Gulf. To truly protect these species, we need to think on the same scale they live their lives — across the whole seascape, not just small pockets of it. Matt Rayner Complete blanket marine protection works, and it can work fast in terms of the recovery of species, and it needs to work fast. This whole journey towards marine protection has been traveling at the speed that a kina grazes because it has been so slow. We're talking about changing the area of protected area in the Gulf from about point 3% to about 6% now the global standard is 30% and that is a global biodiversity framework that the New Zealand government has signed up to. The government will say that this new marine protection bill will bring in 18% marine protection, but unfortunately, that includes, it's a little bit cheeky, we believe, because that includes sea floor areas that will be protected, but you can still fish the water column above them. So, in terms of high protection, where generally no fishing is going to be allowed. It's about 6% of course, there's another issue that recently, to the dismay of conservationists, at least, the government is going to allow ring Net Fishing in two of those high protection marine areas.
Laura Skerritt Ring-net fishing is when a net with floats at the top and weights at the bottom is used to circle around a school of fish then quickly pulled closed to catch them.Matt Rayner It's been one step forward, half a step back, for about 12 years over successive governments and. The action on marine protection in this country has been just glacially slow, and I think people are starting to realise that we're falling behind the rest of the world in that area, and we really need some action to catch up. The Gulf's too beautiful to allow this decline to continue.  It's like the great last wilderness.  Laura Skerritt So, what can we do to help seabirds?  One way is by supporting fishing methods that don’t damage our marine habitats, like trawling, which destroys the seafloor and kills or injures seabirds and marine mammals, what’s known as bycatch. It also helps to be curious about where your fish comes from — ask restaurants where and how the fish on their menu was caught. Or next time you’re in the supermarket check the labels and ask yourself the same sort of questions. Take a look at the best fish guides online and only buy kai moana that is caught in a sustainable way. Or get political, raise your concerns directly with your local MP and add your voice to the call for change. And protect seabirds out on the water and on islands, be careful not to drive your boat through flocks of resting birds and respect biodiversity laws –– don’t take your pets to islands where seabirds come to breed.  Giving them safe, undisturbed places is one of the biggest gifts we can offer. Matt Rayner Biodiversity loss is one of the big challenges, aside from climate change on the planet, and I got news for the public, it's going on right out there, in the Hauraki Gulf. Nearly everything is declining, ongoing. Karoro because it's an adapted to our rubbish and eating our waste. It's doing all right, but for most other species, red billed gull, white fronted turn the Kawau Tikitiki, the Korora, the little blue Penguin, these species are declining in the Gulf. Once they're gone, they're gone. Once they're gone, they're gone. And we're you know, the world is poorer for it.

Laura Skerritt That was ‘Manu Moana (00:25):
a bird’s eye view’ brought to you by Auckland Museum, supported by the Tennyson Charitable Trust. Written, produced and hosted by me, Laura Skerritt. Sound design by Sara O’Brien, with production support from Annabel Walker.  The executive producer was Teresa Cowie from Connect Content.  Thanks to our guest Dr Matt Rayner, and to bird sound archivist Les McPherson- who generously shared his recordings with us for this episode.To learn more about seabirds of the Hauraki, read Matt’s blogs on our website, or find out more about the Hauraki Gulf/Tīkapa Moana Marine Protection Bill, visit the links in our show notes.  If you’re enjoying The Amp, please help others to find us by sharing with friends or whānau or leaving a review.