Counting couples on the Chathams: tūturuatu breeding season

Every year as breeding season for the tūturuatu approaches, we head out to the remote Chatham Islands to do a census of the population. But what is the tūturuatu, why a census, and how many are coupling up this year? Expert Rose Colleen went on the trip and gives us the goss.

The tūturuatu – or shore plover – is a small, plucky shorebird with a big character. They’re not very well known, partly because there are so few left and partly because most of the small population is in the Chathams.

Tūturuatu are critically threatened. There are less than 250 of them in the world. Their main stronghold is on pest free Rangatira Island, but there’s a growing population of around 70 on Waikawa Island in Hawke’s Bay and a few birds on Motutapu Island in the Hauraki Gulf. There are also birds in a few captive breeding facilities.

They weigh in about 60 grams (about the size of a song thrush) but are incredibly strong flyers – even juveniles can fly up to 100km just to get home. They have a distinctive peeping call and make an endearing full-body bobbing move. Males have a dark face mask and cap on the top of their heads, which distinguishes them quickly from other species. Most of them are curious and bold, and will come right up to check you out, shout at you, and try to see you off their territory when they have a nest.

That’s part of the reason these little guys are so vulnerable. They don’t seem to realise how small they are and because they nest on the ground above high tide line, they’re an easy target for predators like cats and rats. If rats were to arrive on Rangatira there would be precious little time before the shore plover population was exterminated.

In terms of biosecurity, shore plover’s vulnerability means they’re an early detection tool for a pest incursion. Rangatira is home to thousands of burrowing seabirds and other vulnerable species, some critically endangered like the black robin and Chatham petrel. If a rat arrived the race would be on to catch the rat and save these species. So every time rangers are on Rangatira, their first job is to check on the shore plover.

But we also have an official census twice a year – before and after breeding season – to more accurately monitor the population.

About twenty shore plover are colour-banded to make individuals easy to identify. A couple of these colour-banded birds will disappear from the population each year through natural causes, but if more than five are missing we’ll continue searching for these specific birds. If it was confirmed more than the usual number of birds was missing, an incursion response would swing into action.

For this year’s pre-breeding census, four of us headed out to Rangatira. During September, the birds become territorial as they get ready for nesting and remind their neighbours of their boundaries. So most of the birds aren’t moving around too much and we can walk around the coastline counting pairs.

First and foremost, we were counting tūturuatu. But we were also dodging fur seals, battling gale force winds, ducking dive-bombing skuas, and seeing who could find the biggest Rangatira spiders at night on the way to the long-drop toilet.

We did the census three times (over 3 days), and each census took about 6 hours. We split into two teams – one heading to the south-eastern coastline and the area known as The Clears (a large open area of salt meadow and tussock land). The other team walked the northern coast.

We searched by listening and looking for the little white dots that are the shore plover – they often give themselves away by calling, flying, and moving as they feed around rock pools. We scanned far away areas with binoculars. Shore plovers can sometimes be difficult to spot because they’re fairly camouflaged and blend in with their surroundings, so we had to walk slowly, be alert and very observant.

This year the population numbers looks similar to the last few years, and all colour banded birds were sighted. We counted 131 birds, which included a total of 48 breeding pairs.

So it’s business as usual on Rangatira – just in time for the couples to get down to business.

The birds will start laying eggs around November, and chicks will start to hatch around December. We’ll return to the island in February to do a post-breeding census and check the breeding success. By then most of the tūturuatu chicks will have fledged and birds like black robins, petrels and shearwaters will be nesting and feeding their babies. It’s an awesome time of year to be visiting!