Tūturuatu Telegraph: Turning the tide for a unique shore bird

Department of Conservation —  15/12/2021 — Leave a comment

What sports a cap, bobs like no-one’s watching, is equal parts feisty to friendly, and number around 285 across their wild and captive populations? One of our most threatened endemic birds, the tūturuatu or shore plover, also known as tchūriwat’ to Moriori on Rēkohu / Chatham Islands, where the largest wild population resides.

The shore plover is described as a bird in need of urgent PR. With just 250 individuals left in the wild on several predator-free islands, it is one of the world’s rarest shore birds, facing issues related to real estate, genetics and a pandemic. Through collaboration and cooperation with tangata whenua, tchakat henu, community groups, and other stakeholders, the DOC-led Shore Plover Recovery Programme aims to turn the tide on this bird’s fate. The bi-monthly ‘Tūturuatu Telegraph’ takes a closer look at what it takes to bring this unique species back from the brink of extinction.

Captive bred shore plover at the Isaac Conservation Wildlife Trust.
📷: Sabine Bernert

Shore plover are colourful shorebirds that once frequented the coastline of Aotearoa, from rocky platforms to sandspits, river mouths to tidal estuaries. They were early casualties of the Norway rats and cats that arrived with European settlers, disappearing from the mainland in the 1870s. For more than 100 years, the only known population of around 120 birds was on South East (Rangatira) / Hokorereoro Island in Rēkohu / Chatham Islands, off the eastern coast of the South Island.

Shore plover are small and stocky birds, weighing around 60g. They are mainly mid-brown above and white below, with distinctive dark caps on their heads, edged with white. An easy way to distinguish the sexes is by their face; males have a black face, females brown, and juveniles are whitish with a dark brown eye-stripe. In contrast, shore plover have bright red beaks and legs.  Their wings are fairly rounded but don’t let that fool you – they are strong fliers, sometimes returning hundreds of km to where they were reared despite efforts to relocate them to predator-free islands. More on that later.

Shore plover flying… note the rounded wings.
📷: Janice McKenna

At the Department of Conservation (DOC), we don’t like to anthropomorphise species, that is, attribute human characteristics and behaviour. But we can’t stop shore plover enthusiasts from doing so, especially when they are helping save the species, right? We particularly like geneticist Ilina Cubrinovska’s hilarious description of shore plover as “feisty potatoes”, thanks to their personality, size and shape. She describes a visit to their stronghold on Rangatira Island, where shore plover ran towards her, bobbing their heads rather adorably to intimidate her. It is this kind of behaviour, combined with their natural curiosity outside of breeding season, that makes them so susceptible to predation.

In terms of breeding, shore plover are in it for the long haul, forming monogamous pairs, with long-term fidelity to both mate and site. They nest under cover of vegetation, boulders, or driftwood, most likely to avoid natural predators such as the now extinct laughing owl / whēkau, rūrū and kārearea / New Zealand falcon. Shore plover usually lay 2-3 eggs in October, and replacement clutches are laid after loss through to January. The eggs are a beautiful pale olive colour with dark vermiculations, a fancy word to describe a wiggly pattern. Incubation takes about 28 days, while the fledging period (when birds get their adult feathers) varies between 1 – 2 months. During this time, being the great parents they are, they vigorously defend their territories and chicks.

Clearly, a population of just 120 found on one island is incredibly risky to the continued survival of the species. The main short-term goal of the Shore Plover Recovery Programme, therefore, is to establish wild populations at five or more locations, with an overall population of 250 or more mature individuals. To achieve this, shore plover are bred from around 11 breeding pairs in captive breeding facilities, with a goal to reach 18 pairs. Facilities include the Isaac Conservation & Wildlife Conservation Trust in Canterbury, Pūkaha National Wildlife Centre in Wairarapa and Cape Sanctuary in Hawke’s Bay.

Shore plover chicks bred at a captive breeding facility

This strategy has been thwarted by several issues. First, is that predator-free islands with habitat suited to shore plover are thin on the ground. Their preferred habitat features rock platforms to forage on for marine and terrestrial invertebrates and the occasional small fish, with vegetation and/or boulders at the back to nest in. And of course, these islands need to be free of predators. Attempts have been made to settle shore plover on five new islands but only two have been successful thus far. These islands are Mangere Island / Maung’ Rē in Rēkohu / Chatham Islands and Portland Island (Waikawa) in Hawke’s Bay while a third site, Motutapu Island in the Hauraki Gulf Marine Park, hangs on by a thread.

Panorama of rocky platform habitat of shore plover on Portland Island (Waikawa).
📷: Jamie Quirk
Shore plover chicks on Portland Island (Waikawa)
📷: Jamie Quirk

Keeping these islands free from predators isn’t always easy, and just one rat or stoat can devastate a population. A prime example is the recent stoat incursion on Motutapu Island, where three of the 13 resident shore plover were preyed on before they were evacuated. Prior to this, attempts to establish populations on Waikawa in 2012 and on Mana Island (near Wellington) in 2007 were hampered by rat incursions resulting in the loss of more than 80% of the resident birds. It was suspected that a single rat was the cause in both cases. Fortunately, a population has been re-established on Waikawa and is doing well, with 80 birds. However, a second attempt to establish a population on Mana Island in 2020 was again unsuccessful, this time due to avian predation and birds dispersing to the mainland.

Which leads to the next issue – shore plover are both curious and have strong fidelity to where they have been reared. Sometimes after release, they have been sighted on neighbouring islands or the mainland, or even undertaking long trips (835km in one case!) to return to their breeding facility.

Meanwhile, rearing shore plover chicks in breeding facilities hasn’t been smooth sailing either. Shore plover, especially chicks, are very susceptible to avian poxvirus, spread by mosquitoes, mites or flies. Vaccine trials for avian poxvirus undertaken by researchers at Massey University proved unsuccessful on captive-bred shore plover. However, genetic research undertaken at the University of Canterbury discovered that the cause is most likely genetic inbreeding, as all captive-bred shore plover share one of four grandparents. Check out Ilina’s 4-minute explanation.

The good news is that researchers found the genetics of wild shore plover on Rangatira Island to be distinct from captive-bred shore plover, and likely to be more receptive to the Avian Pox vaccine. As a result, eggs were transferred from wild pairs in the Rangatira population into the captive-breeding programme last year, to boost genetic diversity. The resulting chicks are now at breeding age, and their offspring will hopefully be able to be vaccinated against avian poxvirus. In the meantime, at around one month in age, shore plover chicks in captive-bred facilities move to purpose-built insect-proof aviaries to protect them from the disease.

Male shore plover.
📷: Don Merton

While the road to shore plover recovery isn’t easy, Dave Houston, lead for the Shore Plover Recovery Programme, is hopeful. “We have a great team working on this – iwi/imi, site managers, researchers, and captive institutions, along with the support of the NZ Nature Fund. Between us, we can restore shore plover to places they’ve been absent for 150 years.”

If you would like to follow this journey to recovery for shore plover, look out for these bi-monthly blogs, subscribe to The Tūturuatu Telegraph newsletter, and follow us on Facebook.

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