Return of the godwit
Thanks to satellite tracking, we now know that godwits fly the 12,000 km journey from Alaska to New Zealand without ever stopping.
Imagine a bicycle wheel, right? Take away the half of it. The hub of the wheel is Banks Peninsula: this is the central nodal point for the whole east coast of the South Island. The Southern Alps from Marlborough down to Southland. Everything that breeds in these braided river systems comes from the coast to the south, migrating north, but doesn’t go round Banks Peninsula. Instead, these birds cut inland over Christchurch and end up at the Avon and Heathcote estuary. We’re like the Heathrow Airport of the South Island.”
Andrew Crossland is walking the shores of that estuary or this airport—on a windy March day. A Christchurch City Council ranger, he knows these waters and their wildlife intimately. Thirty-eight years old now, he has been coming here since he was a boy. Terns, shags, stilts, oystercatchers, all manner of shorebirds and waders, he knows them well. Even personally.
“This white-faced heron here,” he says, indicating a bird I couldn’t tell apart from the next one. “I’ve known him for more than 10 years. He’s really tame. He lives up on the hill up the back.”
Then there are the paradise shelducks: they’re everywhere in Christchurch now, but Crossland can recall when there was just one pair, in 1997, and how they nested by a pond near a school in Beckenham. He can tell you, too, that there are five species of cormorant here: the whole of Europe has only three.
Pointing out dotterel footprints, he says: “I started monitoring the birdlife on the estuary when I was at high school, so a lot of these birds I’ve been monitoring for 24 years straight. I’ve got about 17,000 pages of field notes on birdlife here. In terms of birdlife this estuary is probably monitored more closely than any other in New Zealand.”
All birds are equal, but in terms of public affection and admiration, some birds are more equal than others. The godwit is the one we Kiwis seem to have the softest spot for, with the exception, perhaps, of the kiwi itself. You don’t, however, tend to find the kiwi in poetry, as you do the god-wit. It has been name-checked, famously, in Charles Brasch’s poem The Islands.
Always, in these islands, meeting and parting Shake us, making tremulous the salt-rimmed air; Divided, many-tongued, the sea is waiting, Bird and fish visit us and come no more. Remindingly beside the quays the whiteShips lie smoking; and from their haunted bay The god wits vanish towards another summer.
The Islands and in Robin Hyde’s novel The Godwits Fly, James McNeish’s book As for the Godwits, and Bridget Armstrong’s play Flight of the Godwit. Maybe it’s the beauty of the word itself (origin, alas, obscure); but more likely it’s because New Zealanders identify with godwits which, like us, are always leaving the country and coming back. March is the time of year when the godwits take off for their long migratory flight to Alaska, where they feed and breed before returning to New Zealand in September and October. They come and go from several estuaries throughout the country but the Avon/Heathcote has become particularly identified with them, perhaps because the people of Christchurch have taken them to their hearts. When the birds go, as many as 600 citizens gather to farewell them; when the first ones return, the cathedral bells are rung in the city.
Ornithologists have known for a long time that godwits cover an enormous distance: from Alaska to New Zealand it’s about 12,000 kilometres. Only the Arctic tern flies further, from Antarctica to the Arctic. What no one realised until relatively recently is that most of the godwits do the return trip non-stop. Flying continuously (not even gliding) over the ocean at an average of 80 km/h, they make the journey in six to eight days.
Thanks to transmitters attached to the birds, we now know that this is the world’s longest non-stop bird flight. The Arctic tern takes frequent rests on the water and fishes for food; the godwits, having stuffed themselves before leaving, don’t even stop to eat.
Hail, then, Limosa lapponica!—or, to give it its Maori name, kuaka! It’s by no means the only migratory bird to come to these shores, but it works the hardest to do so. According to legend, it even gave the first voyagers to Aotearoa from Polynesia the idea that there was something down south worth travelling towards: they kept seeing it hurtling past once a year, as if it had somewhere definite to go and wasn’t going to stop till it got there.
If that’s true, then it could have been one of those light-bulb moments when Kupe, say, scanned the skies above Hawaiiki and muttered to himself, “Hmm…where are those birds going? Must find out…”
Right now, it’s late March and Andrew Crossland is taking us out on the Southshore Spit, on the northern side of the estuary. Round the tip of the spit and there the godwits are, several score of them, oceanside, gathered at water’s edge. Mostly bar-taileds but maybe a few blacktaileds or Hudsonians among them. Facing north. Like passengers at a departure gate. Waiting for the right moment to announce itself—a slight shift in the wind, perhaps.
“Most of the movement relates to the atmospheric conditions—favourable tail winds, that sort of thing,” says Crossland.
The hundreds of godwits that came here six months ago make their departures over a five-to-six-week period in groups of five to 25, and stick together the whole way, as far as anyone knows. “It makes sense from an energy point of view that they fly in a flock,” explains Crossland, “because the lead bird takes the pressure and the other birds are able to go in the slipstream.”
But about 300 juveniles—you can tell them by their brown breasts; the adults ready for breeding have brick-red plumage—stay over for the winter, rather than risk the trip. So if a godwit can survive the South Island winter, why would any of them feel the need to leave at all?
“Well, ‘Why come?’ is the other question,” replies Crossland. “You have to look at it from another perspective. There’s a whole heap of related species that breed up in the Arctic and you’ve got 24-hour or 18-hour daylight in the Arctic summer, so you can live right through: they can do so much in one day.
“The permafrost melts, so all of the mosquitoes and other insects are in huge abundance; there are amazing food supplies for them. Just thousands and thousands and thousands of square miles of habitat with, like, no people.
“So those birds are breeding up there in the world’s best breeding conditions for that short number of months. Then it gets cold real quick and they can’t survive there; they’ve got to get out of it. So they migrate southwards.”
Why New Zealand, though? What’s so special, for in stance, about the menu here at the Restaurant Chez Avon/Heathcote?
“This is a very rich feeding ground. The oystercatchers are feeding on shellfish, mainly cockles: there’s an amazing abundance of cockles in this estuary. The godwits are mainly feeding on polychaete worms—sea worms that you dig up for bait.
“The stilts are visual feeders, not probers, so the other two are probing but the stilts are picking stuff off the surface—little flies and crustaceans. You can see them walking around looking.”
The godwits’ journey north takes them to a halfway stop on the shores of the Yellow Sea between China and Korea, where there’s reliable estuarine feeding (or has been up to now: those grounds are being threatened by massive reclamation projects). Then, after four or five weeks building up their strength, they fly on to Alaska. (It’s the return journey that godwits fly non-stop.)
How many survive the trip north? We know from banded birds. Explains Crossland: “Of the, say, 70 birds that we caught about three years ago, more than 60 came back the following year and there’s probably about 50-odd here three or four years later, so there’s actually quite high survival.”
The survival rate is better here, too. Earlier this year two people deliberately set their dogs to chase the flock, but thankfully that kind of hoonery is uncommon these days. Most people know not to walk too near and disturb the birds, says Crossland, who praises the strong community spirit around the estuary.
“People just become exposed to the information and the children learn it as well. People didn’t know what the birds were in the past—they were just some seagulls. Now every one in this neighbourhood knows what a godwit is and knows what an oystercatcher is and knows how to behave.”
Crossland, who worked for DOC before getting this job, also speaks highly of the ecologically minded local authorities. The city council spotted his talent early. “When I was about 17 I went along to a meeting on the estuary and stood up and told all these things I’d been seeing. Basically, various council people asked me to give them information and I became their kind of main adviser. It’s the same with the plant people and other people around Christchurch, the council’s always been really good that way.
“Christchurch in my 25 years’ involvement hasn’t had very much of that banging your head against a brick wall, against all the bureaucrats who sit in their little offices with their Tupperware lunch tins and their shorts and their walksocks going, ‘Bring back Andrew Mehrtens’. We haven’t had that.”
Fast forward six months to late September, and we’re back on the estuary to see the godwits that have jetted in from Alaska, as per their annual schedule. They’ve been touching down regularly for the past three weeks and more are still coming in, bedraggled and hungry. First they get a bit of kip; then it’s serious tucker time. They’ll even feed through the high tide and within a few days will have regained so much weight that they’re indistinguishable from those who wintered over.
This time Crossland takes us round in his 4WD, talking non-stop about wildlife and wetlands. He talks so knowledgeably (and quotably) about his work that you can’t help but envy him, as someone who clearly enjoys doing what he does for a living—wildlife monitoring and habitat restoration. He seems at one with the natural world, attuned to its moods, wise in its ways.
Once, when he lay prostrate and motionless in the sand, oystercatchers used his body as a windbreak. “If you dig a hole in the sand and just sit in it,” he says, “the birds will often come around you.”
We drive out along the southern shore of the estuary, towards Redcliffs and Sumner, where property values have migrated skywards in recent years, infesting the hillsides with flash new homes, their angularity jarring with the natural environment in a way that you can only see them as attempts to subdue nature rather than harmonise with it. Here, according to a real estate agent’s sign, is “where your future starts today!”
Moving along, on a mild grey day punctuated by spitting rain, we park for a while on top of Balmoral Hill, which has a tremendous view of the Canterbury Plains to the west, stretching to the Southern Alps, and Pegasus Bay to the north. Below us lies the entire Avon/Heathcote estuary, which has three main components: 850 ha of mudflats, 250 ha of oxidisation ponds and about 100 ha of lowland paddock. The shorelines are constantly shifting, and not always just at the sea’s behest: human care and attention modify this tidescape too.
Driving back past McCormacks Bay, for instance, Crossland points out three artificial islands in a lagoon. They were built in 1991 as a roost for godwits, he says, “but we’ve been manipulating the habitat as of late, and we’ve not cut the grass for a couple of years to pretty much make those islands unusable as bird roosting sites”.
As some big wetlands around the margin of the estuary have been developed, they really want to encourage the birds to use those sites.
Just past Ferrymead there’s a marshy area of 20 ha to the left: once a horse paddock, it’s now the Charlesworth Wetland Reserve. Birds like godwits and oystercatchers love it.
Five years ago, Crossland and his colleagues scraped the paddock to bare earth and planted native saltmarsh plants that have since self-colonised.
“Salt is wonderful,” he says, “because it’s the best weedkiller you can get. It basically kills the invasive grasses, and most of the plants that like salt are native plants.
Further along the road going north we come to the Bexley Wetland Reserve, part of which used to be a car wrecker’s yard. Contaminated material in the soil was put in a mound and capped with layers of gravel and silt, then topsoil and mulch so it could be planted up. A moat right round this site—deeper on the outside, shallower on the inside, so birds can feed—keeps predators like cats out. They’ve thought of everything.
Now we’re back where we were in March, at Southshore Spit, only on the inland side this time, looking out on a long sandbank exposed by the low tide. There are shafts of sunlight over the city to the west, the roar of surf behind us to the east. The sandbank’s covered in birds, most of them taking a rest on one leg or two. Every now and then the godwits at the far right end of the sandbank fly up, circle around and land again. Crossland sets up his spotting scope on a tripod and describes the view.
“In the centre of the roost are the variable oystercatchers; they’re the biggest ones. Beyond them are the pied oystercatchers, so they’ve both got dry feet, and then on the edge there are the godwits. The godwits get pushed down to the bottom of the roost. So when a tidal surge comes through, all the godwits get pushed up into the air.”
Why? “Because they’re smaller. It’s largely because of their size. It’s just bullying on the roost.”
In any case, he says, godwits tend to be edgier than the other birds, nervous about predators. “When they’re in the breeding grounds, anything big and brown that moves, like a skua or bird of prey, they’re really nervous. So when they see a skua [which preys on their chicks in the Arctic], they go crazy.
“These guys have just come from being Mum and Dad Godwit on a wee nest in the middle of the tundra, and anything on the horizon that looks wrong freaks them out. They’re here and all of a sudden they see a brown seagull and whoa! the whole lot go up. If one goes up, the whole lot will go. But they tend to relax as the summer goes on.”
We know a lot about godwits. We know that the females are larger and have longer beaks, that the birds can live for about 20 years. We know what they like to eat and what makes them nervous. And we know—well, we’re pretty sure—that, astonishingly, young godwits barely a month old fly from Alaska to New Zealand without their parents shepherding them along.
But we don’t know how they pair up, especially when they commute up and down the world’s largest ocean. Even Crossland can’t figure that one out. “Can they only re-meet by going to the breeding ground and landing on the nesting site and hoping that the mate comes back? Do their young find their own way here and actually go to where Mum and Dad are, or do they go somewhere else?”
One of Crossland’s tasks is to count godwits. For many years, he says, he would count various bird populations up to eight times a month; now he does them perhaps once a month “because I understand from my earlier data how the seasonal abundance pattern works”.
He thumbs through a battered old diary. Back on August 7 he counted 171 godwits that had wintered over, but internal movement brought a big drop to 64 on September 4. On September 7 there were suddenly 274 godwits, but by the following day, 326. The first influx had clearly arrived from Alaska, as some of them still bore traces of their breeding plumage. On September 15 there were 394. And today? 1030.
The likely maximum summer population is about 2000, but whatever the final number, at any given time there are hundreds of the creatures on the land or in the air, constantly moving about and mingling with one another: how can he possibly tell how many there are?
“I count the legs and divide by two,” he says with a grin.
A part from the Avon/Heathcote, godwits are fond of just about anything that qualifies as a large food-rich estuary. They can be found every summer, says Massey University ornithologist Phil Battley, congregating in northern harbours like Kaipara, Manukau and Kawhia; the Firth of Thames is another popular spot, as is Farewell Spit. Their total New Zealand population is currently estimated to be about 80,000.
The affable Battley, a senior lecturer in zoology in Massey’s Ecology Group, studies all kinds of shorebirds but for a while godwits were of particular interest to him: he was part of an international research project run by the US Geological Survey out of Alaska, a project which culminated last year in a fluke discovery that set the ornithological world alight and even made the general news headlines.
For centuries, birdwatchers have relied on banding in order to find out where migratory birds go. Even today, an elaborate system of different-coloured bands and flags attached to birds continues to provide critical information about migration patterns. But it obviously cannot tell us what the birds are up to during their flights, nor how long it takes them to get from point A to point B. For that, ornithologists are relying increasingly on satellite telemetry.
Last year, several godwits summering over in the Firth of Thames were equipped with transmitters before they left for the north. Bob Gill, of the US Geological Survey, explains how this procedure is carried out.
“The larger females can handle a unit that we surgically implant in them. We have a veterinarian along with us when we catch birds, the birds are anaesthetised, they’re hooked up with a heart monitor, a respirator—it’s just like surgery you or I would have for removal of an appendix or something.
“The radio’s inserted into an air sac underneath the rear end of the bird, so the antenna comes out right by the tail.
The males, being smaller, can’t handle the weight of that implanted unit, so they have a much lighter solar-powered unit that has to be applied externally. Those are attached through what’s called a figure-eight leg-loop harness… imagine the bird stepping into it, with the unit fitting on the back and the antenna, again, coming out horizontally.
“We designed these antennas so they’d be coming out on the plane of the bird and wouldn’t be sticking up, inducing wind drag.”
The signals sent out are picked up by National Oceanic & Atmospheric Administration satellites and tracked on computer screens by Gill and his colleagues in Anchorage.
Thanks to this technology, it has been confirmed that the bar-tailed godwit (Limosa lapponica baueri) flies non-stop further than any other bird in the world. In a Proceedings of the Royal Society paper, Gill, Battley and eight other authors state that in 2007 a female godwit unceremoniously named E7 flew 11,680 km from Alaska to New Zealand without stopping, easily exceeding the previous official record of 6500 km, flown by far eastern curlews.
It was a fluke finding, Battley admits, because by rights E7’s transmitter batteries should have run out of puff long before she got near the South Pacific. Researchers had hoped at best to track her northward migration and maybe just a bit of the trip back.
“The batteries should last for about 300 hours of transmission time and last year we had about 600 hours of transmission time,” says Battley.
What’s more, we know that E7 made the same trip again this year, because Battley saw her last summer at Miranda on the Firth of Thames, and again in September, “looking very shabby and worn out, probably because she had just come in on migration”.
This year, however, only two of five transmitters worked all the way up to Alaska, and none at all worked for the return trip. And now there are no more plans to do further transmitter work, as funding provided by the Packard Foundation for godwit research has run out.
“Each unit costs about $5000–$6000. And in some ways the key questions have already been answered,” says Battley. In any case, he adds, no matter how smart the satellite technology, the battery aspect is always going to be problematic.
“Unless someone can develop a radically different battery, that’s always going to be the heaviest part of the arrangement. The way to get around the battery is to have a solar panel on it, but of course that has to be on the outside of the bird, and that’s when you start getting interference with the wind flow.”
The survey has revealed two other remarkable aspects to the flight of the godwits. One is that the birds don’t stop to eat: by steady feeding before they leave, they bulk up to the point where nearly half their body weight is pure fat, which they then burn off as fuel when they fly. The second thing is that their wings are always flapping: they rarely glide, because they’d waste energy regaining height if they did.
Even satellite telemetry, however, can’t tell us how high they fly.
“We don’t know that,” admits Gill. “We have reports from colleagues on oceanographic vessels of godwits blown past them a couple of metres off the waves; we have other reports of a colleague having to crank his neck back and look at small spots in his binoculars way up high, 1000 metres up probably or higher, but just smoking across the sky to the south.”
Nor do we know why they leave when they do. Can they somehow sense when the meteorological moment is right? Or, as another paper co-authored by Gill puts it, “Is weather across the Pacific teleconnected such that certain departure cues at northern latitudes assure relatively favourable conditions along most of the route?”
If so, what effect will major climate change have on them? According to Gill, the greater threat is the projected changes in both the frequency and the intensity of the storms that come across the north Pacific, the storms that produce the winds that get these godwits started on their migration.
“If all storms increase in frequency and intensity, I think godwits will adapt to it; but if the storm track shifts for whatever reason, it could very well not provide the tailwind they need.”
In the meantime, he and his colleagues “propose that this transoceanic route may function as an ecological corridor rather than a barrier, providing a wind-assisted passage relatively free of pathogens and predators”.
Stunning stuff. Through studying them so closely and for so long, presumably Gill has grown very fond of godwits. “How do you not,” he replies, “given what they do?” It’s a sentiment with which most of us Kiwis clearly would agree.