The Plight of the Pohowera
Kaikōura’s Banded Dotterel Study continues to shine a light on the serious plight of New Zealand’s inconspicuous endemic shorebird, pohowera, which is being pushed towards extinction because of severe ongoing decline.
The double-banded dotterel (Charadrius bicinctus bicinctus) is a small wader belonging to the plover family of birds. Once widespread, it’s thought their numbers have dipped to 18,000 and declining. Classified as Naturally Vulnerable, they can be found throughout New Zealand, primarily breeding on sandy and shingle coastal beaches, sand dunes, inland shingle riverbeds, undeveloped drylands, and on open alluvial flats.
Though the biggest numbers are found in inland Canterbury and the Mackenzie Basin, banded dotterels nest on Kaikōura’s gravel beaches and their density is particularly high close to the peninsula on the beaches directly to the north and south.
For the past seven years, researcher and advocate Ailsa McGilvary-Howard, her husband Ted Howard, and their band of helpers have worked tirelessly to protect and raise awareness about Kaikōura’s banded dotterel population. Despite their efforts though, the writing is on the wall.
The couple, who were both recently awarded the Queen’s Service Medal for services to conservation, have lived in Kaikōura for more than 30 years. Both have backgrounds in conservation, studying under Sir Alan Mark and John Morton while at university.
Ailsa’s fascination with banded dotterels came about as part of a lifestyle change following her husband’s diagnosis of cancer. Having updated her camera, she became interested in the banded dotterels nesting in South Bay as photographic subjects on the beach. It led to a growing awareness of the birds and their breeding behaviour. ‘People had told me that there were banded dotterels nesting on the beach, but that they were hard to see. So, I wanted to see for myself,’ explains Ailsa.
A self-confessed plant person (she has a degree in botany), she wasn’t prepared for the raft of emotions that followed. Captivated by these plucky little birds’ boldness yet vulnerability, she couldn’t believe the extraordinary effort they put into reproducing and was ‘absolutely devastated’ to see the nest fail. ‘It really impacted me,’ she says. ‘The female usually lays three eggs which equal half of their body mass. That would be like us having a 35 kg baby. They’re enormous eggs for their size.’
Ailsa found other nests, none of which produced chicks either. ‘It struck me that if something doesn’t breed, it’s on a trajectory to disaster.’ She took her concerns to the local branch of Forest & Bird and with its support, launched a self-funded project, the Banded Dotterel Study Kaikōura, in August 2015.
Initially, she thought three years would be enough to gather some reliable data, but the project continued to evolve. ‘I was completely naive. I had never done anything like this in my life. I had no idea what it would involve or how grim the situation was.’
Her objectives were to measure the breeding success of banded dotterels in the area, identify the factors that led to nest failure, and come up with some management strategies to improve nesting success while at the same trying to raise community awareness about this unique endemic species hiding in plain sight.
Banded dotterels are about 20 cm long and weigh just 60 grams. Perfectly camouflaged by their environment, they are a small, compact brown and white plover with a short black bill, relatively long dark legs and large round dark eyes. Breeding males have a broad chestnut breast band with a narrow black neck band above it; females have both bands but they are duller.
Most banded dotterels migrate for the winter, but how far and where to differs. Those from the South Island high country tend to head west to Tasmania or south-eastern Australia, while those that nest in the lowland South Island and central New Zealand rivers go north to harbours and estuaries of the northern North Island. Birds that nest on the coast tend not to migrate significant distances, but the Kaikōura birds that have been sighted on the migration have been seen from Port Waikato to Omaha.
They begin to arrive at the breeding grounds in early July. Like all braided river birds, they nest on the ground. However, unlike terns and gulls, they are territorial, rather than colonial nesters. Their strategy is every pair for itself, explains Ailsa.
First eggs are laid from August to mid-December. The female lays between two and four grey to pale-green or olive and black speckled eggs which both adults take turns incubating for 28 days. The chicks are advanced at birth. They are very independent and incredibly mobile. They are also self-feeding, so the family is quick to leave the nest. Chicks fledge at close to six weeks. Parents remain close and attentive, providing warmth when needed and peep out instructions to stand perfectly still if a threat is detected.
They rely on stealth and camouflage to hide them from predators, but while that works well for aerial hunters like harrier hawks that hunt by sight during the day, it doesn’t work for mammalian predators that hunt by smell at night. A nesting dotterel is a beacon of scent in a barren desert, especially for cats. ‘To a cat, banded dotterels are the best smell in the world. They see a nest as roast dinner,’ Ailsa says.
Their invisibility also puts them at risk of human disturbance with people standing on or driving over their nests. Even chicks on the beach can be disturbed, without people even knowing they’re there. ‘They deliberately don’t want you to see them, but that does make it difficult.’
Ailsa started off monitoring just the nests in South Bay, but over time that grew to include nests from The Caves to Mill Road, including South Bay and Gooches Beach. In her first season, of the 20 nests studied, there were only eight chicks hatched and just one fledgling survived. The number of nests studied is now up around 120, but reproductive rates remain bleak. This year preliminary results showed of the 118 nests studied there was a 97 per cent failure rate of eggs to fledgling adults. They also lost a number of adult birds.
Over the years they have tried everything to mitigate losses, from nesting cages to protect them from predators, adding nesting cameras, introducing live-capture traps for hedgehogs, and marking nests to make them more visible for people. They have also banded as many birds as possible so they know who returns and who doesn’t. To date, they have banded more than 200 birds.
It’s now pretty clear cats are to blame for most of the destruction, says Ailsa. ‘When we first got cameras, the first predator was a hedgehog but they tended to eat the eggs, not the adult birds. Nothing prepared me for seeing cat, after cat, after cat. I had no idea the profound number of cats in our ecosystem. They leave telltale signs around the nest. It’s not just feral cats, but domestic cats too. They actually go out and target the nests. They’re not just doing it for food; they’re doing it for sport.’
Though her work is yet to change the outcomes for banded dotterels, there have been many positives to come out of it. These days Ailsa no longer works on her own. She works collaboratively with the Department of Conservation (DOC). The local rūnanga has also come on board with a trapping programme along 120 km of coast. The plight of the banded dotterel is also now at the forefront, no longer hidden in plain sight.
‘It has been superbly interesting. There has been a huge amount of growth that has occurred in all sorts of ways and it has challenged me in all sorts of ways. But the lows have been unbearable at times. Predation doesn’t start until September, but once it does, it’s like a rollercoaster ride and you just have to hang on. By December you can see the light at the end of the tunnel. [The results are] pretty grim,’ she says.
Going forward, Ailsa hopes more can be done to save the banded dotterel population at Kaikōura, but she believes it’s going to take a miracle to turn it around. ‘At this stage, the reproductive rates are so grim and the trajectory on the steep side of exponential decline that extinction is almost a certainty.’
Legislation that mandates night-time cat containment would make the single biggest difference for dotterel survival. ‘This would enable us to remove feral cats, and dotterels could really bounce back,’ she says.
