11 Oct 2018

Banding together for banded dotterels

From Our Changing World, 9:07 pm on 11 October 2018

Banded dotterels are small, dumpy shorebirds. They breed on South Island braided riverbeds, as well as on beaches around the country.

At Eastbourne, near Wellington, a small population of dotterels is closely watched by curious locals, including George Hobson, an enthusiastic 15-year-old birder.

A male banded dotterel.

A male banded dotterel. Photo: George Hobson

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A brisk wind ruffles the water of Wellington harbour into a froth of whitecaps, and scours across a wide flat expanse of grey pebbles, chunks of driftwood and a scattering of low scrubby plants at the back of the beach.

Binoculars in one hand and a small remote-triggered trail camera in the other, George climbs over the seawall separating the houses of Eastbourne from the beach.

Fifteen-year old George is a home-schooled bird enthusiast, and a keen pohowera or banded dotterel minder. He is out here every week, making regular checks on the four pairs of dotterels that turn up each spring to breed.

George Hobson regularly visits the beach at Eastbourne to monitor the small banded dotterel population.

George Hobson regularly visits the beach at Eastbourne to monitor the small banded dotterel population. Photo: RNZ / Alison Ballance

George is more than a casual observer. He’s part of a group of like-minded birders who are involved in a banded dotterel nesting study, organised by local environment group Mainland Island Restoration Operation, or MIRO for short.

This is the third year of the study, and already this season the four resident dotterel pairs have laid eggs, only to have their nests fail shortly afterwards.

George doesn’t know what caused the nests to fail – predators such as rats, hedgehogs and neighbourhood cats might be to blame, or it could be that they were disturbed too many times by off-leash dogs.

But, undeterred by failure, the plucky birds are already re-nesting.

Fellow banded dotterel watcher, Joan, walks on the beach every day, and the previous day she reported finding a new nest.

George’s task is to install a remote-triggered trail camera near the new nest; he hopes it might shed light on what is happening at the nest. That’s not as easy as it might sound.

First, he has to find it. There is not much to look for – a simple scrape in the gravel, and speckled eggs that bear an uncanny resemblance to the small rocks around them.

A female banded dotterel.

A female banded dotterel. Photo: Ailsa McGilvary-Howard

George heads to where he thinks the nest might be, and hears a distinctive high-pitched ‘pink’. It’s the call of a banded dotterel, and out the corner of his eye he catches a movement.

It’s a male banded dotterel, darting briskly around as it searches for insects.

Another ‘pink’, this time from a slightly different direction, gives away the female bird.

George knows that the adults are deliberately drawing attention to themselves, and that suggests they have something to hide. He’s confident he’s in the right part of the beach, but he still can’t find that elusive nest.

A quick phone call and Joan appears to guide him to it.

Joan describes herself as a complete amateur, but admits that she is a keen bird spotter who is “getting quite good at finding nests.”

“These are such sweet birds,” she says. “They’ve got a special character.”

The nest they find holds three green eggs, speckled with black spots. Perfectly camouflaged, they are nestled amongst rocks and bits of driftwood.

The adult birds will take turns incubating the eggs for up to 28 days, relying on stealth and the camouflage of their brown backs to hide them from predators.

The problem is that the birds are expecting aerial hunters like harrier hawks that hunt by sight during the day. But in modern New Zealand they have to contend with mammalian predators that hunt by smell at night. And a nesting dotterel is a beacon of scent in a barren desert.

A banded dotterel nest with three eggs on Eastbourne beach is just a scrape in the gravel.

A banded dotterel nest on Eastbourne beach is just a scrape in the gravel. Photo: RNZ / Alison Ballance

George quickly deploys the motion-triggered camera, which can work in the dark as well as during the day, and he and Joan move away to allow the parents to return to duty.

As they watch through binoculars, Joan identifies which birds they are. Each bird has a small flag on one leg with a unique lettered code, and she manages to read the letters on the female’s band: PCC.

“She’s paired up with PCA,” she says, “This is a couple from last year who’ve paired up again this year. They’re old friends”

A couple of minutes later, PCC slips back onto the nest and tucks the eggs under the warmth of her brood patch. The male feeds quietly nearby.

All going well, the chicks will hatch in a few weeks. George says the grey chicks are “basically little balls of fluff with legs. And within a couple of hours they are up and off the nest, running around and feeding themselves.”

The self-sufficient chicks stay with their parents for six-or-so weeks, before becoming independent.

A banded dotterel chick is up and running just a few hours after it hatches.

A banded dotterel chick is up and running just a few hours after it hatches. Photo: Ailsa McGilvary-Howard

George says that come the end of summer the dotterels will head a few kilometres south to the Pencarrow Lakes.

While the Eastbourne birds don’t seem to travel far, birds from other parts of the country make longer migrations over winter. Many North island birds migrate to harbours in the Far North, while birds from the South Island’s braided rivers head across the Tasman to Australia.

But all this is many months in the future. In the meantime, George, Joan and the other dotterel watchers will spend the summer following the progress of ‘their’ birds.

They will keep reminding the local dog walkers to keep their dogs on leashes or to stay well away from the nesting area at the front of the beach.

If they can work out what is destroying the nests, they will deploy the right kind of trap and hopefully get rid of any predators.

And by the end of the breeding season they’ll have some more information to add to their growing body of knowledge about their feathered neighbours.

Bird of the Year

George is campaign manager for banded dotterel in the 2108 Bird of the Year competition. Voting closes 4pm Sunday 14 October 2018.

In 2018, George was awarded the A.T. Edgar Junior Award by Birds New Zealand.

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