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Millions of shorebirds have just flown north for their annual migration and for some, it may be a final goodbye. Ann Jones investigates the worldwide threats to migratory shorebirds’ incredible lifecycle, including habitat destruction, human disturbance and predators.

The birds look like they are waiting for the bus.

They line up facing nor-nor-west, looking into the middle distance, sullen, appearing to not care about their fellow travellers.

There is no squabbling, no feeding and no preening. Just a resolute stare toward the horizon.

The birds that aren’t ready to migrate, they’re all just going about their daily business, they’re feeding, they’re preening, they’re having little squabbles, chatting to each other all that sort of stuff. But the birds that are on a mission, so to speak, are just standing there.

Then, on an invisible cue, the wings expand, the birds rise, screaming and egging each other on, and they’re off.

To Russia.

These are the last moments of the bar-tailed godwit on Australian soil (for a year anyway).

‘It’s an absolutely incredible sight. It’s phenomenal,’ says Mandy Soymonoff, a warden at the Broome Bird Observatory.

‘When they lift off into the air, they start calling to each other like it’s the most exciting thing they’ve ever done.’

‘The birds that aren’t ready to migrate, they’re all just going about their daily business, they’re feeding, they’re preening, they’re having little squabbles, chatting to each other all that sort of stuff. But the birds that are on a mission, so to speak, are just standing there.’

‘What happens to some of the shorebirds, is before they’re going to migrate, the organs that they’re not going to use during the migration actually shrink down—so the organs that they would use for digestion, for instance. ‘

‘They’ve done the feeding that they going to do, they’ve put on that fat which they’re going to use up during the journey and they’re ready to go. They’re just waiting for those invisible cues, getting themselves orientated before they head off.’

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Their intestines probably need a break anyway, as the birds have been intensively eating while in Australia, trying to almost double their body weight in preparation for the intercontinental flight.

‘These birds will hang out in Australia for between four and six months generally over our spring-summer seasons, and then leading up into autumn-winter they will depart on a northward migration and head up to the northern reaches of the globe,’ says Dan Weller from Birdlife Australia.

‘A lot of them breed in the Arctic Circle in places like Siberia and Alaska, basically travelling up there to take advantage of a very short window of opportunity during the Arctic summer.’

In their lifetime, some of the birds will fly the equivalent distance of a trip to the Moon and back. That’s 700,000km spent seeking seasonal food in sites like the Arctic tundra.

‘The snow and ice recedes and you have an abundance of other animals that are also taking advantage of that very short window of opportunity during the Arctic summer,’ says Weller.

‘There is an absolute abundance of food, so much so that when these chicks hatch they don’t have to travel vary far from their nests at all in order to feed. They can basically sit tight and feed off things like mosquitoes and flies and other types of invertebrates that are within easy reach of their nests.’

The chicks can feed themselves very shortly after hatching, and the parents fatten up again and shoot off some weeks before the chick is heavy enough to fly all the way back to the Southern Hemisphere. The young birds follow by themselves some time later after gorging on Arctic insects.

Rob Clemens, who is currently writing a PhD on shorebirds at the University of Queensland, put the birds’ quest for chub in context.

‘If you imagine that I’m a shorebird and I’m going to take off in about three weeks,’ he says. ‘I’ve gotta put on about 5kg a day, until I’m about a couple of hundred kilos and I’m ready to do a non-stop marathon to [Russia].’

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The massive weight gain on top of long legs made for walks on the beach and specialised beaks for poking down sand holes means that shorebirds don’t necessarily have the easiest time flying.

‘They’re not very aerodynamic birds. They’re like a football with wings,’ says Rob Clemens.

Though comfortable among the waves of the estuary and able to weather the ocean winds while on migratory flight, there is an irony to the fact that shorebirds, which spend most of their lives around water, aren’t very good at swimming.

That means that they can’t drift down to the ocean’s surface to rest for a period while en route north: they flap the whole way.

‘They’re flying non-stop, some of these birds, for four to eight days, they don’t have a chance to sleep,’ says Clemens.

‘They are able to apparently rest different sections of their brain independently.’

Being ready for that sort of energy expenditure means a sizeable weight gain, and if you don’t put on enough fat, you might not last the journey. Ideally, it’s beak down, tail up and eat every single thing you can get your hypothetical bird fangs into for most of the time you are in Australia.

Unfortunately, shorebirds are known for being easily alarmed. They are incredibly sensitive. Dogs running on the beach, quad bikes or four-wheel drives constitute what scientists call ‘disturbances’.

When disturbed, the birds’ response is very much weighted towards flight over fight. They’ll take off and soar around, often for long periods of time, until the threat reduces.

‘They’re in this sort of weight-gain program, and every time you are forced to fly around you are not putting on the mass that you were hoping to. If you are not able to make that trip, there are not a lot of places to stop and refuel,’ says Clemens.

‘The next big place that they need to make it to is South East Asia—one of the big places is the Yellow [Sea] between Korea and China.’

By the time the birds arrive at the halfway point in Asia, almost all their body fat has been used in the flight.

‘They’re kind of skin and bone and feathers and they need to put on that weight again. They have these two massive weight gain periods that they need to go through to make that trip up to the Arctic,’ says Clemens.

‘One of the issues that’s impacting these birds is the loss of habitat that’s happening in the Yellow Sea. Work at the University of Queensland has highlighted that anywhere from 50 per cent to two thirds of the intertidal habitat that these birds rely on has been lost over the last 50 years or so.’

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The Yellow Sea is a bottle neck in terms of shorebird migration, one of the critical and highly used stop-over points in the East Asian-Australasian flyway.

In 2007 Birdlife Australia reported that 150,000 shorebirds simply did not reappear on the return journey from the north. The cause was found to be the destruction of a patch of intertidal zone in the Yellow Sea.

The problem with habitat destruction of such a mobile group of species is that researchers do not see the result of, say, a golf course development on the Chinese shoreline until a year later when whole flocks of birds simply do not appear on their way out of Australia again; they’ve starved somewhere on their journey.

Various organisations help to monitor the numbers of birds that migrate through Australia, which are thought to hover at around five million in total.

However, in the 25 years of monitoring, many migratory bird species have been declining rapidly, such as the curlew sandpiper, whose population has decreased by 50 to 80 per cent.

Wave the waders goodbye Listen to Ann Jones and a panel of bird experts discussing the athletic abilities of shorebirds on Off Track.

The birds are often incredibly specific about their environment and their food source, which in the current pressurised ecological environment can play against them. They may only eat one sort of invertebrate, and their phenomenal navigation skills can lead some species them to return to within metres of their previous nesting or refuelling spot.

‘Their navigation systems are remarkable,’ says Clemens.

They can sense magnetic direction using two little magnetic bits in their bills and they also use the sun, moon and the rotation of stars around as both a compass and a map.

‘There is some indication that these birds are able to see lines of polarity in the sky,’ Clemens says.

‘If you can imagine being able to see more of the colour spectrum, you’d be able to see these lines of polarity pointing either north or south and as time advances, the position of the sun is a little different and again, you both get a calendar and a map.’

‘There are also some suggestions that some of these birds can detect infra-sound.’

Crashing waves on a beach produce such sounds, and it is thought the birds may be able to hear these sound waves over long distances.

‘If by chance a storm comes up on you and you’re half way across the Pacific Ocean, it’s a real handy thing to detect where land might be.’

It’s such an incredible, perilous journey, putting sections of your brain to sleep, flapping continuously day and night, lurching through storms, looking out for kestrels and other predatory birds and lugging the spare tyre of energy you’ve managed to accrue over the southern summer over thousands of kilometres.

As the birds have almost all flown out to the north for this year, twitchers all over Australia are wishing them well, waving farewell, and hoping that this time, it isn’t forever.

Head outside and venture Off Track for a show about the great outdoors. Listen to the environment discussed by the people who live in and love it.



