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Bird arrivals, departures a priority at new airport in Africa

By Leon Marshall In total darkness I felt my way through the sugarcane. I had come to watch with my own eyes what I had observed the previous day on a radar screen: millions of swallows taking off from a wetland reed bed wedged between the cane plantations. But all I could make out was...

By Leon Marshall

In total darkness I felt my way through the sugarcane. I had come to watch with my own eyes what I had observed the previous day on a radar screen: millions of swallows taking off from a wetland reed bed wedged between the cane plantations.

But all I could make out was a soft rustle, as from a breeze stirring leaves. I knew this was the sound of the birds leaving, early risers that they are. What was I thinking? I could barely make out my hand, even if held against the first faint glow touching the eastern horizon.

I would have to be content with what I had witnessed at sunset the day before, when the swallows came in to roost. The spectacle of so many birds landing for the night is a major attraction in this part of South Africa.


Photo courtesy of Angie Wilken,

The roosting site for an estimated three million swallows is the Lake Victoria Conservancy, a 90-acre (35-hectare) wetland at Mount Moreland, a quiet rural village off the Indian Ocean coast north of the port of Durban.


Visitors gather on the terraces of Mount Moreland to enjoy the sunset spectacle of swallows flocking to roost.

Photo by Leon Marshall

Birdwatchers start gathering on terraced lawns above the reed bed well before sunset. They bring camp chairs and picnic baskets, and, the sun reflecting off their beer and wine glasses, wait for one of the greatest shows of nature to begin.

The swallows start arriving in small flocks about half an hour before the sun disappears. I would not even have noticed them had it not been for Angie Wilken, chair of the Mount Moreland Ratepayers Association, who was standing next to me. “Look,” she announced excitedly, “there they come!”


Photo courtesy of Angie Wilken,

The little birds steadily gathered force, until they became a swirling mass in the fading light. Then suddenly they ducked into the reed bed, as if sucked into a vortex. There during the night, it is reckoned, they drop a ton of manure from insects they consumed during the day.

The barn swallows that roost here, also known as European swallows (Hirundo rustica), are summer visitors to South Africa from Europe and Asia, where they breed.


Photo of barn swallow courtesy of Angie Wilken,

What it is about the Mount Moreland site that makes them return there year after year in such breathtaking numbers is not clear.

Whatever the lure of the reeds, it was enough to present a serious headache when it was finally decided, after nearly four decades of indecision, to proceed with construction of a new international airfield for Durban.

Named after the legendary Zulu king who, in the 1820s, had his royal residence nearby, King Shaka International Airport is scheduled to open for business on May 1, a few weeks before the 2010 Football World Cup tournament commences in South Africa.


The swallow roost happens to be right in the flight path of aircraft that will be arriving and departing at the new airport. So real was the danger considered to be of the birds being sucked into jet engines that there was talk of destroying the reed bed.

But there was an outcry from conservation organizations, including BirdLife South Africa, BirdLife International, the Endangered Wildlife Trust (EWT), and WWF South Africa.

Google Earth satellite image

If the roost was destroyed, conservationists warned, the effect on breeding barn swallows numbers would be felt throughout Europe.

The deadlock was broken through an extraordinary instance of cooperation between a developer and environmentalists, aimed at ensuring the safety of the airliners and the preservation of the roosting site.

The breakthrough, says Albert Froneman, an ornithological consultant engaged by Airports Company South Africa, came when it was understood that it took the birds less than an hour to gather and settle at dusk and a few minutes to fly off in waves before dispersing at dawn.

It was also noted that the roosting site was 1.6 miles (2.6 kilometers) from the end of the runway and in a valley 295 feet (90 meters) below the runway’s elevation. The angle of approaching and departing aircraft would put them about 741 feet (226 meters) above the roost and also well above the birds’ normal flocking height.


Photo of construction of King Shaka International Airport by Leon Marshall

The knowledge of the birds’ flight patterns led to incorporation of an exceptional safety plan into the legally prescribed environmental impact assessment for the airport. It resulted in the installation of a radar system to keep tabs on the comings and goings of the massive bird flocks, and the development of a procedure that would allow air traffic control to pass on a reliable risk assessment and safety advice to pilots.

A U.S.$300 000 radar system was custom-built by a U.S. company and placed at the runway end nearest the swallow roost. Vertical and horizontal scanners cover a radius of 2.3 miles (3.7 kilometers) and show clearly when there is a build-up in bird density.


The radar installation at the end of the King Shaka International Airport runway.

Photo by Leon Marshall

A computer system alerts the airport’s bird and wildlife unit and the air traffic control tower when there is any risk of significant numbers of birds straying into the flight path.

In the control tower a bird warning light will change from green to red, while in the control room of the airport’s bird and wildlife unit, which is responsible for clearing animals off the runways, there will also be an amber light that will enable the unit to start assessing the situation on radar monitors even before the red light flashes–allowing time to prepare an advisory for the control tower.


Christopher Jones monitors the radar screen recording swallow activity on the flight path of aircraft.

Photo by Leon Marshall

Froneman says it might happen on rare occasions that flights have to wait a few minutes before taking off, or slow their landing approach. Incoming planes should hardly ever have to go into a holding pattern, though it could happen when for some reason the swallows flock at a higher altitude and stay there longer than usual, he says.

The radar system is already operating and is being run and monitored with the help of a student. The purpose, says Froneman, is to develop an algorithm based on a clear understanding of the birds’ behavior patterns and of the language in which risk assessments get conveyed.

Everybody, right up to the pilot, must know exactly what the situation is, he says.

The protocol is being prepared in consultation with all the parties, including ornithologists and the airlines, but it will need to be finally approved by the South African Civil Aviation Authority.

There will be plenty of time to familiarize everybody with the system even after the old Durban airport shuts down at midnight on April 31 and the entire operation switches to King Shaka International Airport on May 1.

By then the birds will already have left for their northern sojourn, and it will be another five months before they start trickling back.

Watch a video of the Mount Moreland swallows and get more information on the Barn Swallow Website.

Leon Marshall.jpg

Nat Geo News Watch contributing editor Leon Marshall is an environmental writer in South Africa. A leading political journalist and executive editor for Africa’s largest newspaper group for years, he has won numerous awards, including a 2004 Reuters-IUCN Media Award for Excellence in Environmental Reporting. Leon has covered climate change from a global and African perspective, having attended conferences on the issue in many parts of the world. He has written extensively on the ambitious transfrontier-parks program of the sub-continent and is now writing a book on the subject.

Read Leon Marshall’s blog posts >>

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Meet the Author

Author Photo David Max Braun
More than forty years in U.S., UK, and South African media gives David Max Braun global perspective and experience across multiple storytelling platforms. His coverage of science, nature, politics, and technology has been published/broadcast by the BBC, CNN, NPR, AP, UPI, National Geographic, TechWeb, De Telegraaf, Travel World, and Argus South African Newspapers. He has published two books and won several journalism awards. In his 22-year career at National Geographic he was VP and editor in chief of National Geographic Digital Media, and the founding editor of the National Geographic Society blog, hosting a global discussion on issues resonating with the Society's mission and initiatives. He also directed the Society side of the Fulbright-National Geographic Digital Storytelling Fellowship, awarded to Americans seeking the opportunity to spend nine months abroad, engaging local communities and sharing stories from the field with a global audience. A regular expert on National Geographic Expeditions, David also lectures on storytelling for impact. He has 120,000 followers on social media: Facebook  Twitter  LinkedIn