She’s the pilot. The sole passenger. The navigator. The engine. The refueller. She’s Flight 95773.
It is the first day of autumn, one year ago. She lifts off on an epic 14 560 km journey. Part of this will be a five-day non-stop 5 912 km flight, mostly over the Indian Ocean, a journey one scientist describes as “amazing”.
She’s an Amur Falcon, a small bird of prey not much bigger than a pigeon. Falcon 95773 is built for long-haul flight. Her sleek tapered wings power her to speeds of more than 50 km/h and allow her to glide on thermals for long distances. The small shark-toothed markings on the feathers of her breast reveal she is an adult.
What makes this Amur Falcon special is that sitting on her back is a matchbox-sized GPS transmitter that will beam data to several satellites orbiting 850 km above the earth. Tracking 95773 will be expensive. The 5g transmitter on her back costs R26 000. Add another R26 000 to download the information from the satellites. She is one of 10 falcons that were trapped in Newcastle last January and fitted with transmitters.
The people behind the venture don’t believe in giving birds names, but they have given her, and nine other falcons, numbers. Each is the ID of the GPS Platform Terminal Transmitter (PTT) strapped to their backs. Hers is PTT 95773.
The bird lovers and scientists behind the venture are hoping these small birds with their tiny transmitters will solve one of ornithology’s great mysteries. Where 95773 is heading on that first day of autumn is known. The mystery is her route, not her destination: the breeding grounds of Mongolia. For a long time ornithologists have debated the route that Amur Falcons take to Mongolia. There have been attempts to plot the transcontinental migration, but all ornithologists have been able to rely on are odd sightings through east Africa and the Middle East. Whole legs of the journey have been missing. But advances in technology and the work of a handful of amateurs will change this. Here’s how the story goes.
On January 10 last year, Professor Bernd-Ulrich Meyburg arrives in Newcastle, KwaZulu-Natal, from Germany. He’s a plastic surgeon with a passion for birds. Meyburg has made a name for himself in birding circles from the work he’s done in studying the migration paths of birds of prey. He says a book about the Lesser Spotted Eagle sparked his passion as a schoolboy in West Germany. On reading the book, the youngster becomes fascinated with the bird’s long migration to southern Africa.
By 1994 the fall of the Berlin Wall and access to satellite telemetry finally allow Meyburg to fulfil his childhood dream. He and his wife, Christina, fit transmitters to four adult Lesser Spotted Eagles and track the complete migration of one of the birds to Zambia. Transmitters become smaller and smaller and he then tracks the migrations of other raptors. In 2008 Meyburg is given a prototype transmitter to test. It weighs about the same as a teaspoon of sugar – just 5g. On August 9, 2008 he fits the transmitter to an adult female Eurasian Hobby he catches near Berlin. Meyburg follows the Hobby’s migration to Angola. It flies via the island of Elba, south into North Africa and arrives in Angola 49 days later. With this success, he wants to try the transmitter on something even smaller.
His choice: the Amur Falcon. His destination: Newcastle. The reason: just 1 km from the town centre is the largest-known roost of Amur Falcons in the world. Between December and March every year, an estimated 26 000 Amur Falcons take up residence in the tall pine trees that line Allen Street, a major thoroughfare through the town. The ideal spot to catch the falcons. The problem: how to do it. About two months before he arrives in South Africa, Meyburg approaches Birdlife Northern Natal. “He asked us if we would be able to capture the falcons using high-altitude nets,” veteran bird ringer Rina Pretorius remembers.
At the time Pretorius knows a lot about mist nets and catching birds, but she’s never heard of an Amur Falcon being caught using these nets. The problem: they fly too high, and if the birders want to catch them they will need to raise the nets tens of metres alongside the pine trees. Electricity giant Eskom and funding from the local municipality come to their rescue. Cables are strung through the trees, long poles erected and then they put in a pulley system to hoist the nets into the air. By December 12 they are ready for a trial run. Just after dusk Pretorius and the team achieve a South African first. They net their first Amur Falcon. By the end of the evening they have caught five more. Each bird is ringed and released.
It is time to call in the Meyburgs. Bernd and Christina arrive in Newcastle on January 10 and that evening join the bird catchers. They spread out their nets and prepare to raise them as Meyburg lays out the tools and transmitters on the table in the lapa. They are ready. In the fading light columns of falcons, thousands strong, reel above the roost site. So many that the standing joke among the ringers is not to look up with your mouth open…To draw the birds closer to the nets, the team uses a lure, a method known in ringing circles as “callback”. They have recorded the call of the Amur – kew kew kew… kew kew kew – and play it loudly on Pretorius’s bakkie sound system.
“The idea,” explains Sylvia Francis, another ringer, “is that birds follow (other) birds that make the most noise because they believe they have the fullest crops. What they plan to do is roost close by and then follow that particular flock, believing they know where there is a lot of food.” Soon the falcons begin descending, darting among the trees looking for a branch for the night. Then the mist net catches the first of four birds, including 95773, trapped that evening. The catchers untangle the birds from the net, place each in a small cloth bag, and take them to the lapa.
Falcon 95773 is the first to be weighed. “Bernd told me that I could do the first bird, because I had prepared all the infrastructure,” Pretorius says. The catchers have a strict rule: so as not to hinder the flight of the bird, the transmitter cannot weigh more than 3 percent of the bird’s mass. 95773 comes in at 160g. “Bernd suddenly got very excited, his eyes never left that bird,” remembers Pretorius. She rings 95773, measures her and takes a blood sample. Meyburg takes over. He fits a small wire harness across the bird’s chest to hold the transmitter high on her back and positions the antenna to follow the contour of her tail. This is when she becomes 95773. When they’re done, Pretorius, mindful of the raptor’s sharp beak, carries the bird into the open. Pretorius places her on a chair to give her a few moments to recover from the ordeal of her capture. Then 95773 lifts off into the night.
Five days later they meet their target of 10 birds: eight females and two males. With the first part of their mission over, Bernd and Christina Meyburg return to Germany. This is too early for the launch of her migration, but soon 95773 begins revealing part of the hidden life of an Amur Falcon. “We found out that she moved a lot at night between roosts,” says Pretorius. “The Roberts book said that they hunt only 50km from their roost, but we found her travelling to Memel and Standerton.” In Germany it is Christina Meyburg’s job to access the satellite website and download the data. The first glitch comes soon after the 10 birds are released: three of the transmitters stop working. No one knows why: it might be that there is a glitch with the transmitters, or it could be that three birds have died.
But not 95773. Her transmitter keeps beaming data, and what they learn is that for two months she wanders, criss-crossing northern KwaZulu-Natal, hopping between the different roosts, and then she moves into Swaziland. Amur Falcons favour open grasslands, where they gather in big flocks and feed on insects like dragonflies and flying ants. Sometimes they go for bigger prey, taking barn swallows on the wing. Meyburg and company suspect she is building up vital fat reserves for her journey ahead. Ornithologists refer to these rest stops as stopovers, migratory bird refuelling stations, where a bird can take time out to carbo-load for the next leg of the journey.
Then, at 11 a.m. on Friday, March 21 last year, the satellite sends the team the data that they have been waiting for. 95773 has begun her migration to the breeding grounds in Mongolia.
High above the Lebombo Mountains on the Swaziland border, she crossed into Mozambique. The mountains fell away and then she flew over the flat mopane forests of western Mozambique. She pushed northwards, guided by something we don’t yet understand. 95773’s flight across Mozambique was swift. For 24 hours, she kept on the wing, covering 1 036 km. Her journey cut northwards at an average speed of 43.2km/h. For a while she stuck close to the Zimbabwean border before turning slightly east towards Tanzania. After a night of flight she landed in southern Tanzania.
For the next eight days she slowly made her way north. She passed through Tanzania and then Kenya, and on March 30, arrived in southern Somalia. There she stopped for a couple of days. She began moving again on April 5 and progressed slowly into Central Somalia. There again she stopped to refuel, this time for five days. 95773 would have hunted, filling her crop with insects. She’d need the high protein found in the locusts, flying ants and dragonflies to give her the energy for the hardest and most dangerous part of her journey.
Back in South Africa the scientists waited, too – for the first time they would “witness” the transoceanic crossing of an Amur Falcon. For the first time the transmitter would tell us exactly where she was when she struck out across the featureless blue ocean. But this still left two of the great migratory mysteries unsolved.
The first of these was: how did she navigate? What was the guiding hand that took these long-distance travellers over thousands of kilometres to their exact destination? Somewhere deep inside the Amurs is an invisible compass that scientists have yet to find and understand. One theory is that it might take its bearing from the sun. But how then did it fly so accurately through the night?
Dr Craig Symes of Wits University speculates: “They possibly rely on celestial cues, or magnetic fields, or a combination of both. It’s also possible that different birds use different methods of navigation.” And then there’s the second mystery the transmitter could not answer. Do birds sleep while they fly? Some biologists believe that migratory birds forgo sleep during these long flights. Others suspect these birds have an autopilot switch that controls their flight and takes over navigation while the rest of the brain sleeps.
On the morning of Friday April 16, after her five-day rest, 95773 began a journey scientists have called “amazing.” She lifted off and began flying a course parallel to the Somali coast. Below her she would have seen dry scrub land as she passed within a couple of hundred kilometres west of the Somalia capital Mogadishu. Not far from the northern Somalia town of Ufeyn the falcon, with a wingspan about the length of an average home PC, and weighing a little more than a tin of tuna, left the horn of Africa.
Ahead of her was the blue of the sea, the Yemen gulf and an ocean crossing of more than 3 000 km. On the next day, Saturday April 17, she was tracked close to the Arabian coast at 6.46 a.m. South African time. Just before landfall on the Oman coast her compass told her to change direction, she turned slightly to her right, and the Arab peninsula fell behind her.
On Sunday April 18, two days after she had struck out across the sea, 95773’s position at 6.46 a.m. was near the Arabian coast. On Monday April 19 the satellite placed her 270 km southwest of Karachi, Pakistan at 5.45. Her oceanic crossing was nearly over. Hours later 95733 was again over land. But she flew on. 95773 had made the crossing in two days and five hours. She was the fastest of the seven remaining birds that continued to be tracked, the first to reach the shores of India.
On Tuesday April 20, at 4:12 a.m., satellites had her logged in eastern India; she was still on the move. And then on Wednesday April 21 she was near Mandalay in eastern Burma. Here 95773’s feet finally touched land, or more likely the branch of a tree.
The non-stop journey of five days had taken her an incredible 5 912 km at just under 50km/h. But her journey was not yet over. After a six-day stop, she continued moving slowly north east. On May 8 95773 arrived. Her transmitter recorded that she was in the middle of the Inner Mongolia Autonomous Region of Xilin Gol, about 450 km north of the Chinese capital of Beijing.
This was the heart of the Amur Falcons’ breeding grounds. She had travelled 14 560 km and she was just half way through her journey.
Some of the other birds hadn’t even made the ocean trip in one go. A male called 95775 had stopped over on Socotra Island, in the Arabian Sea for a couple of hours, before resuming his flight. “Maybe he had a girlfriend there he stopped to visit,” laughs Rina Pretorius, the bird lover who had helped trap 95775 and several other Amurs in Newcastle. His crossing was the longest at two days and 18 hours.
Shortly after 95773 arrived in Mongolia, the German bird lover who sparked the research, Dr Bernd-U Meyburg and his wife Christina, battled to get a fix on the birds from the weak signals. So no one knows what 95773 did for the next two months. Perhaps she found a mate, and reared a clutch of chicks, as millions of other Amur Falcons were doing in Mongolia.
Now the team had its longest wait. Would she fly home? They would know only when the transmission improved.
In late October an e-mail landed in Pretorius’s inbox. An excited Meyburg told Pretorius 95773 was on the move again. She and the other falcons had taken flight and were now in an area where all seven transmitters could beam information to the network of satellites high above. The wait had ended. Now science had the opportunity to record the full complete migration of an Amur Falcon.
On October 28, satellites picked 95773 up in Assam, in Northern India. The large female falcon was the first to leave, again leading the charge. From Assam 95773 passed over Nagpur and Bombay, then across the Indian Ocean. This time her ocean passage was shorter, a distance of just over 2 500 km, which she covered in two days of non- stop flight.
With landfall came the acacia scrub-land of Somalia, as 95773 turned south flying through East Africa. Like before, her journey was a mix of quick sprints and lengthy stop-overs. She cut her way further inland towards central Africa. Pretorius followed her progress as she inched closer to Newcastle. On the evening of November 27, she slept over in southern Zimbabwe, just 75 km from the border of South Africa. Twelve days later she crossed into South Africa. On December 11, she slept at Samcor Park in Pretoria and two days later satellites recorded her in Volksrust. The Newcastle roost now just 50 km away.
Three days later Pretorius received Meyburg’s latest e-mail update. Pretorius grabbed her camera, binoculars and rushed to her bakkie. The e-mail contained co-ordinates and with the help of Google Maps the veteran bird-ringer got a fix. Her chances were slim that mid morning. But she still drove through Newcastle towards the suburb of Lennoxton. She found the tall lone pine tree. Two kilometres away lay the roost from where, 11 months earlier, 95773 had taken off from a camping chair, carrying some special cargo. The tree was empty.
“I just wanted to see the bird, I was hoping maybe I would find her sitting on a nearby telephone line and I would identify her from the transmitter on her back, “she recalls. But Pretorius had missed 95773. The night before, in the rain, 95773 had landed in that pine tree in Newcastle.
Her touchdown ended one of ornithology’s greatest mysteries – a team of amateur birdwatchers had mapped the epic flight of an Amur falcon. 95773 had come full circle.
The falcon had landed.
Submitted by David Shreeve